Showing papers in "European Radiology in 1999"

Contrast-media-induced nephrotoxicity: a consensus report. Contrast Media Safety Committee, European Society of Urogenital Radiology (ESUR).

Abstract: The purpose of this study was, using consensus methodology, to document current understanding of contrast media nephrotoxicity (CMN) and to identify areas where there is disagreement or confusion. To draw up guidelines for avoiding CMN based on the current understanding of the condition established by the survey. One hundred sixty-four statements were mailed to 148 members of the European Society of Urogenital Radiology (ESUR) and to 48 experts in the field of CMN. They were asked about the definition, clinical features, predisposing factors and pathophysiology of CMN and about prophylactic measures. The importance of the statements was rated on a scale from 1 to 10 (1 least important, 10 most important). Fifty-three members (38 %) and 23 experts (48 %) responded. Both groups considered that an increase in serum creatinine that peaks within 3–4 days and a decrease in creatinine clearance are the most important (rating > 7) features of CMN. Enzymuria was not considered important (rating 6). Hydration and the use of low osmolar contrast media were thought to minimize the incidence of CMN (rating > 6). The majority of the responders (84.6 % of members and 95.5 % of experts) believe that the incidence of CMN in patients with normal renal function is less than 5 %. Of the members, 62.5 %, and 35.3 % of experts, believe that the incidence of CMN is 20–30 % in the presence of risk factors. There was disagreement about the definition of CMN, the threshold dose of contrast media above which renal complications may develop, the safe period between repeat injections, the relevance of contrast media renal retention shown on CT and whether contrast media have long-term effects on renal function. The survey showed good understanding of CMN among those who answered the questionnaires, although areas of disagreement remain which require further research. Simple guidelines are proposed.

Dose reduction in CT by on-line tube current control: principles and validation on phantoms and cadavers.

Abstract: We investigated approaches to reducing the dose in CT without impairing image quality. Dose can be reduced for non-circular object cross-sections without a significant increase in noise if X-ray tube current is reduced at angular tube positions where the X-ray attenuation by the patients is small. We investigated different schemes of current modulation during tube rotation by simulation and phantom measurements. Both pre-programmed sinusoidal modulation functions and attenuation-based on-line control of the tube current were evaluated. All relevant scan parameters were varied, including constraints such as the maximum modulation amplitude. A circular, an elliptical and two oval water phantoms were used. Results were validated on six cadavers. Dose reduction of 10–45 % was obtained both in simulations and in measurements for the different non-circular phantom geometries and current modulation algorithms without an increase in pixel noise values. On-line attenuation-based control yielded higher reductions than modulation by a sinusoidal curve. The maximal dose reduction predicted by simulations could not be achieved due to limits in the modulation amplitude. In cadaver studies, a reduction of typically 20–40 % was achieved for the body and about 10 % for the head. Variations of our technique are possible; a slight increase in nominal tube current for high-attenuation projections combined with attenuation-based current modulation still yields significant dose reduction, but also a reduction in the structured noise that may obscure diagnostic details. We conclude that a significant reduction in dose can be achieved by tube current modulation without compromising image quality. Attenuation-based on-line control and a modulation amplitude of at least 90 % should be employed.

A PC program for estimating organ dose and effective dose values in computed tomography.

Abstract: Dose values in CT are specified by the manufacturers for all CT systems and operating conditions in phantoms. It is not trivial, however, to derive dose values in patients from this information. Therefore, we have developed a PC-based program which calculates organ dose and effective dose values for arbitrary scan parameters and anatomical ranges. Values for primary radiation are derived from measurements or manufacturer specifications; values for scattered radiation are derived from Monte Carlo calculations tabulated for standard anthropomorphic phantoms. Based on these values, organ doses can be computed by the program for arbitrary scan protocols in conventional and in spiral CT. Effective dose values are also provided, both with ICRP 26 and ICRP 60 tissue-weighting coefficients. Results for several standard CT protocols are presented in tabular form in this paper. In addition, potential for dose reduction is demonstrated, for example, in spiral CT and in quantitative CT. Providing realistic patient dose estimates for arbitrary CT protocols is relevant both for the physician and the patient, and it is particularly useful for educational and training purposes. The program, called WinDose, is now in use at the Erlangen University hospitals (Germany) as an information tool for radiologists and patients. Further extensions are planned.

Efficient object scatter correction algorithm for third and fourth generation CT scanners.

Abstract: X-ray photons which are scattered inside the object slice and reach the detector array increase the detected signal and produce image artifacts as "cupping" effects in large objects and dark bands between regions of high attenuation. The artifact amplitudes increase with scanned volume or slice width. Object scatter can be reduced in third generation computed tomography (CT) geometry by collimating the detector elements. However, a correction can still improve image quality. For fourth generation CT geometry, only poor anti-scatter collimation is possible and a numeric correction is necessary. This paper presents a correction algorithm which can be parameterized for third and fourth generation CT geometry. The method requires low computational effort and allows flexible application to different body regions by simple parameter adjustments. The object scatter intensity which is subtracted from the measured signal is calculated with convolution of the weighted and windowed projection data with a spatially invariant "scatter convolution function". The scatter convolution function is approximated for the desired scanner geometry from pencil beam simulations and measurements using coherent and incoherent differential scatter cross section data. Several examples of phantom and medical objects scanned with third and fourth generation CT systems are discussed. In third generation scanners, scatter artifacts are effectively corrected. For fourth generation geometry with poor anti-scatter collimation, object scatter artifacts are strongly reduced.

Infarction of omentum and epiploic appendage: diagnosis, epidemiology and natural history.

Abstract: Epiploic appendagitis and segmental omentum infarction are considered to be rare conditions, which may mimic an abdominal surgical emergency. The purpose of our study was to describe clinical findings, US and CT appearance of infarction of an epiploic appendage and omentum, and to determine their epidemiological characteristics and natural history. We retrospectively studied clinical, US and CT findings at hospital admission and follow-up of all patients who were diagnosed at our institution with epiploic appendagitis or omentum infarction between June 1988 and November 1997. We found a relatively high incidence of 40 cases: 20 patients with epiploic appendagitis, 11 with omentum infarction, and 9 in whom it was not possible to discriminate between the both. All 40 patients recovered under conservative treatment without complications. We conclude that US and CT features allow a reliable diagnosis, thereby obviating unnecessary surgery. Discriminating between both conditions is of no practical relevance since treatment and prognosis are identical.

Liver metastases: interventional therapeutic techniques and results, state of the art.

Abstract: The liver is the most common site of metastatic tumour deposits. Hepatic metastases are the major cause of morbidity and mortality in patients with gastrointestinal carcinomas and other malignant tumours. The rationale and results for interventional therapeutic techniques in the treatment of liver metastases are presented. For the treatment of patients with irresectable liver metastases, alternative local ablative therapeutic modalities have been developed. Technique and results of local interventional therapies are presented such as microwave-, radiofrequency (RF)- and ultrasound ablation, and laser-induced interstitial therapy (LITT), cryotherapy and local drug administration such as alcohol injection, endotumoral chemotherapy and regional chemoembolisation. In addition to cryotherapy, all ablative techniques can be performed percutaneously with low morbidity and mortality. Cryotherapy is an effective and precise technique for inducing tumour necrosis, but it is currently performed via laparotomy. Percutaneous local alcohol injection results in an inhomogeneous distribution in liver metastases with unreliable control rates. Local chemotherapeutic drug instillation and regional chemoembolisation produces relevant but non-reproducible lesions. Laser-induced interstitial thermotherapy (LITT) performed under MRI guidance results in precise and reproducible areas of induced necrosis with a local control of 94%, and with an improved survival rate. Interventional therapeutic techniques of liver metastases do result in a remarkable local tumour control rate with improved survival results.

Field strength and dose dependence of contrast enhancement by gadolinium-based MR contrast agents.

Abstract: The relaxivities r1 and r2 of magnetic resonance contrast agents and the T1 relaxation time values of tissues are strongly field dependent. We present quantitative data and simulations of different gadolinium-based extracellular fluid contrast agents and the modulation of their contrast enhancement by the magnetic field to be able to answer the following questions: How are the dose and field dependences of their contrast enhancement? Is there an interrelationship between dose and field dependence? Should one increase or decrease doses at specific fields? Nuclear magnetic relaxation dispersion data were acquired for the following contrast agents: gadopentetate dimeglumine, gadoterate meglumine, gadodiamide injection, and gadoteridol injection, as well as for several normal and pathological human tissue samples. The magnetic field range stretched from 0.0002 to 4.7 T, including the entire clinical imaging range. The data acquired were then fitted with the appropriate theoretical models. The combination of the diamagnetic relaxation rates (R1 = 1/T1 and R2 = 1/T2) of tissues with the respective paramagnetic contributions of the contrast agents allowed the prediction of image contrast at any magnetic field. The results revealed a nearly identical field and dose-dependent increase of contrast enhancement induced by these contrast agents within a certain dose range. The target tissue concentration (TTC) was an important though nonlinear factor for enhancement. The currently recommended dose of 0.1 mmol/kg body weight seems to be a compromise close to the lower limits of diagnostically sufficient contrast enhancement for clinical imaging at all field strengths. At low field contrast enhancement might be insufficient. Adjustment of dose or concentration, or a new class of contrast agents with optimized relaxivity, would be a valuable contribution to a better diagnostic yield of contrast enhancement at all fields.

Spinal cord tumors

Abstract: Spinal cord tumors are rare; however, every radiologist should be able to recognize and readily identify those lesions often found in younger patients or children [1, 2, 3, 4, 5, 6, 7, 8,9]. Early diagnosis plays an important role in the management of the lesions and interferes with the prognosis and final outcome of the patient [10]. Plain X-ray of the spine and CT are of limited diagnostic value in cases of intramedullary pathology. Magnetic resonance imaging should be performed as soon as possible and as the first technique whenever an intrinsic spinal cord lesion is clinically suspected. Systematic analysis of the MR images together with a basic knowledge of the most common spinal cord tumors encountered, including astrocytomas, ependymomas, and hemangioblastomas, should provide a correct diagnosis and lead to appropriate treatment subsequently.

Imaging of trabecular bone structure in osteoporosis.

Abstract: Osteoporosis is a metabolic bone disorder that is characterized by reduced bone mass and a deterioration of bone structure which results in an increased fracture risk. Since the disease is preventable, diagnostic techniques are of major importance. Standard techniques determine bone mineral density, whereas some of the newer techniques focus on trabecular structure. This article reviews structure analysis techniques in the diagnosis of osteoporosis. Imaging techniques applied to the assessment of trabecular bone structure include conventional radiography, magnification radiography, high-resolution CT (HRCT) and high-resolution MR imaging (HRMRI). The best results were obtained using high-resolution tomographic techniques. The highest spatial resolutions in vivo were achieved using HRMRI. The most common texture analysis techniques that have been used are morphological parameters (analogous to bone histomorphometry). Fractal dimension, co-occurrence matrices, mathematical filter techniques and autocorrelation functions are more complex techniques. Most of the studies evaluating structure analysis show that texture parameters and bone mineral density both predict bone strength and osteoporotic fractures, and that combining both techniques yields the best results in the diagnosis of osteoporosis.

Detection and quantification of coronary artery calcification with electron-beam and conventional CT.

Abstract: To identify patients with increased risk of having coronary artery disease (CAD), electron-beam computed tomography (EBCT) was used for years for quantifying calcifications of the coronary arteries. The first direct comparison between EBCT and conventional CT was performed to determine the reliability of widely available conventional CT for the assessment of the coronary calcium score. Fifty male patients with suspected CAD were investigated with both modalities, EBCT and conventional 500-ms non-spiral partial scan CT. Scoring of the coronary calcification was performed according to the Agatston method. Forty-two of these patients underwent coronary angiography for the assessment of significant luminal narrowing. The correlation coefficient of the score values of both modalities was highly significant (r = 0.982, p < 0.001). The variability between the two modalities was 42 %. Mean calcium score in patients with significant coronary luminal narrowing (n = 37) was 1104 ± 1089 with EBCT and 1229 ± 1327 with conventional CT. In patients without luminal narrowing (n = 5) mean calcium score was 73 ± 57 with EBCT and 26 ± 35 with conventional CT. Although images of the heart from conventional CT may suffer from cardiac motion artifacts, conventional CT has the potential to identify patients with CAD with accuracy similar to EBCT.

MR-guided percutaneous excisional and incisional biopsy of breast lesions.

Abstract: The aim of this study was the realisation and clinical application of MR-guided vacuum biopsy for percutaneous excisional and incisional biopsy of enhancing breast lesions. A breast biopsy system and procedure have been developed which allow precise and safe access to breast lesions in any location and use of vacuum biopsy (VB) under MR guidance. Fifty-one patients with 55 MR-detected lesions were examined. Verification of these diagnoses included re-excision histology of all 14 malignancies and for benign lesions retrospective correlation of histology and imaging, assessment of complete or partial removal of the enhancing area directly after VB (40 of 40 lesions) and follow-up MRI (33 of 40 lesions), which in contrast to conventional needle biopsy can be used as proof of representative removal. Fifty-four of 55 procedures (including 15 lesions ≤ 5 mm and another 26 lesions of 5–10 mm size) were successful. One failure was caused by incorrect use of the VB gun. Vacuum biopsy yielded 14 malignancies and 40 benign lesions. With the available verification techniques all diagnoses proved correct. Percutaneous VB became possible under MR guidance. With minimal invasion it allowed increased certainty and accuracy even for very small lesions.

Evaluation of spiral CT in staging of colon and rectum carcinoma.

Abstract: The purpose of our study was to evaluate the capability of a subsecond spiral-CT scanner using two contrast medium phases in staging of colorectal cancer. In our study we included 37 patients with proven rectum or colon carcinoma. Spiral CT was performed following tap-water enema of the colon in the arterial and venous phases of contrast medium enhancement. Our results were compared with the findings of pathological examination after surgery. The tumor's size and extension were evaluated in the arterial and venous phases, the lymph nodes in the venous phase of the CT scan. The tumor was in the rectum (n = 14), sigma (n = 11), descending colon (n = 6), and cecum (n = 6). Two-phase spiral CT had a sensitivity of 97.2% in the arterial phase and 89.1% in the venous phase in detecting the carcinoma. The staging results were in the arterial phase in 30 of 37 cases (81.0%) and in the venous phase in 24 of 37 cases (64.8%) according to pathology. In 27 of 32 patients (84.3%) lymph nodes were detected. The correct classification of the N-stage was possible in 23 of 34 cases (67.6%). The combined use of arterial and venous phases in staging of colorectal cancer can improve the T- and N-stage classification in comparison with using only one contrast medium phase. The arterial phase is superior compared with the venous phase for local tumor staging and the venous phase is used for lymph node assessment.

MRI of the pulmonary parenchyma.

Abstract: Imaging of the pulmonary parenchyma represents a unique challenge for MRI. Limited signal is caused by low proton density, susceptibility artifacts, and physiological motion (cardiac pulsation, respiration). Recently, further improvements in MRI techniques have widened the potential for investigations of pulmonary parenchymal disease. These include very short echo times, ultrafast turbo-spin-echo acquisitions, projection reconstruction technique, breathhold imaging, ECG triggering, contrast agents (perfusion imaging, aerosols), sodium imaging, hyperpolarized noble gas imaging, and oxygen enhancement. By using widely available techniques, MRI is helpful in the assessment of (a) acute alveolitic processes in chronic infiltrative lung disease, (b) detection and characterization of pulmonary nodules, (c) detection, characterization, and follow-up of pneumonia, (d) differentiation of obstructive atelectasis from non-obstructive atelectasis and infarctions, and (e) measurements of lung water content. Chronic bronchitis, bronchiectasis, and emphysema are not readily assessable by routine MRI techniques. More sophisticated techniques are under investigation for MR imaging of pulmonary ventilation and perfusion. They represent the beginning of functional MR imaging of the lung which will be established in the future.

The various MRI patterns of pituitary apoplexy

Abstract: The aim of this study was to describe the various MRI features, in correlation to surgical and pathological findings, in patients who presented with pituitary apoplexy (PA). Eleven patients presenting with PA, were evaluated with various MR protocols including spin-echo (SE) T1-weighted sequences in 9 of 11 patients, post gadolinium SE T1-weighted sequences in only 8 of 11 patients, and with T2-weighted SE sequences in 2 of 11 patients. All patients had transsphenoidal pituitary surgery after MR studies. The severity of presenting symptoms ranged from headaches to coma. Ten patients had pituitary macroadenoma; one had a non-hemorrhagic metastatic lesion into a non-adenomatous pituitary gland. Of the 11 patients, one was studied at the acute stage of PA (1 day after onset), 9 at the subacute period (3–15 days after onset), and one at the late stage (5 months after onset). Images compatible with intratumoral hemorrhage were found in all macroadenomas, whereas the metastatic pituitary lesion did not show evidence of bleeding. All gadolinium-enhanced studies showed partial tumoral enhancement. The SE T2-weighted studies demonstrated areas of low and high signal intensities in keeping with the presence of blood degradation contents. Pituitary apoplexy present with different MR features, including hemorrhagic and non-hemorrhagic characteristics on T1-weighted images. Gadolinium-enhanced images do not provide complementary diagnostic information when the presence of blood is assessed on plain images.

Varicocele: strategies in diagnosis and treatment.

Abstract: Varicocele can be very easily diagnosed by physical examination and subsequently treated when it is painful or associated with testicular hypotrophy. However, palpability of the spermatic vein and reflux in low grade or even questionable varicoceles can be difficult to assess without imaging modalities. This can be a common problem for all physicians treating hypofertile men to decide whether the varicele needs to be treated or not. However, a gold standard that defines the presence of a subclinical varicocele has not yet been established. The different diagnostic tools based on ultrasonography investigated these past years to define a flow reversal in incontinent spermatic veins are presented in the first part of this review, with emphasis on subclinical varicocele. In the second part, we present our experience, together with a review of the literature concerning embolization of the spermatic veins as an alternative to surgery to treat varicoceles.

The pseudocapsule in hepatocellular carcinoma: correlation between dynamic MR imaging and pathology.

Abstract: Nodular hepatocellular carcinoma (HCC) is characterized by the presence of a pseudocapsule (constructed usually from connective fibrous tissue) that appears hypointense on T1- and T2-weighted spin-echo (SE) and gradient-echo (GE) MR imaging sequences without a contrast medium. The presence of vascular structures inside the tumor, which are verified by histological exam, affects enhancement of the PC after administrating the contrast medium: The impregnation is more evident in the dynamic study but also persists on the delayed T1-weighted SE images. The accuracy of MR in detecting the pseudocapsule of HCC and contrast enhancement of the pseudocapsule during dynamic studies were evaluated and related to pathological findings. Thirty-seven HCC were examined in 33 patients and afterwards resected. In capsulated nodules, besides usual hematoxylin, eosin, and trichrome stainings, histochemical and immunohistochemical methods were performed. On a 1.5-T MR unit, T1- and T2-weighted SE and GE FLASH 2D sequences after intravenous injection of Gd-DTPA (dynamic study) were used. In a later phase, T1-weighted SE sequences were repeated. Histologically, the pseudocapsule (thickness 0.2–6 mm) was present in 26 of 37 nodules (70 %). The dynamic study was the most suitable technique to show the pseudocapsule, which was recognized in 80.7 % (21 of 26 nodules). In 5 of 26 cases, the pseudocapsule, not demonstrated by MR, was thinner than 0.4 mm. In 16 of 21 cases, in the early portal phase (30–60 s), the pseudocapsule had an early enhancement, which was more evident later; in 5 of 21 cases the enhancement was observed only in the late portal phase (1–2 min). At histological examination, 14 of 16 pseudocapsules with early enhancement showed a more prominent vasculature than those with enhancement in the equilibrium phase. Magnetic resonance was a reliable tool in demonstrating the pseudocapsule of HCC. The histological examination demonstrated a good correlation between the enhancement behavior and the vessel number of the pseudocapsule.

Exogenous lipoid pneumonia: HRCT, MR, and pathologic findings

Abstract: The objective of this study was to describe high-resolution CT (HRCT) and MR findings of exogenous lipoid pneumonia and to correlate them with pathologic findings A retrospective review of the medical records of our institution revealed seven patients with a diagnosis of lipoid pneumonia based on clinical data, chest films, bronchoalveolar lavage, and follow-up Both HRCT and MR imaging were reviewed by two readers Pathologic examination of the resected specimen or surgical biopsies were also reviewed in the four available cases The HRCT findings were pulmonary consolidations (n = 6) with fatty (n = 3) or unspecific but low attenuation values (n = 3), areas of ground-glass opacities (n = 5), septal lines, and centrilobular interstitial thickening (n = 5) In five of the seven cases, a crazy-paving pattern of various spread was also present, either isolated (n = 1) or surrounding a pulmonary consolidation In two cases traction bronchiectasis and cystic changes consistent with fibrosis were seen At MR imaging (n = 2) a pulmonary consolidation of high signal intensity on T1-weighted image consistent with lipid content was present in one case Pathologic examination (n = 4) showed the coexistence of lobules with lesions of various ages, sometimes in contiguous lobules, within the same patient Recent lesions were those with alveolar fill-in by spumous macrophages and almost normal alveolar walls and septae In more advanced lesions, lobules were filled in with larger vacuoles often surrounded by inflammatory infiltrates of alveolar walls, bronchiolar walls, and septa The oldest lesions were characterized by fibrosis and parenchymal distortion around large lipid-containing vacuoles The HRCT findings reflect pathologic findings in exogenous lipoid pneumonia Although non-specific, consolidation areas of low attenuation values and crazy-paving pattern are frequently associated in exogenous lipoid pneumonia and are indicative of the diagnosis

Interventional MR: interstitial therapy

Abstract: The rationale and results for interstitial therapies via interventional MRI in the treatment of tumors in various regions are presented. Different interstitial treatment techniques are presented based on varying technologies both for tumor ablation and treatment monitoring. Data are presented based on 335 patients, 29–84 years of age (mean age 59 years, 196 men and 139 women) with a total of 932 liver tumors, 16 head and neck tumors and 14 abdominal recurrent pelvic and lymphatic tumors. All lesions had been treated with MR-guided laser-induced interstitial thermotherapy (LITT) via 2516 laser applications and 1856 cannulations. Data in the literature are extremely varying depending on author experience, treatment technique, and the included patient material. In our patient material we were able to achieve a local tumor control of 96.7 % depending on the size of the tumorous lesion, the topographical relationship, and the applied laser parameters. The overall cumulative survival rate of patients with liver metastases was 45.74 months (median 40.97 months, 95 % confidence interval 31.42–50.52). The cumulative survival rate of the patient group with hepatic metastases of colorectal carcinoma was 42.71 months (median 39.33 months, 95 % confidence interval 33.26–45.37). In patients with head and neck tumors a relevant reduction in clinically relevant symptoms such as pain, swallowing disorders, or nervous compression was achieved in 11 of 15 patients treated with LITT. In 14 soft tissue tumors, such as pelvic tumor recurrence and lymph node metastases, a local tumor control was obtained in 68 % of lesions. Interstitial therapies under interventional MRI guidance, such as LITT, results in a high local tumor control with an improved survival rate.

Osteomyelitis: a review of currently used imaging techniques.

Abstract: Conventional radiographs remain the initial imaging modality involved in the diagnosis of osteomyelitis. Bone scintigraphy and its specific agents did not only eliminate the problems of inherent low sensitivity of conventional radiographs, but also increased the specificity to higher degrees. Spiral CT, on the other hand, has solved several diagnostic problems, such as osteomyelitis of the sterno-clavicular junction and hidden areas in the pelvic bones. Magnetic resonance imaging with its multiplanar capability, greater anatomic details and excellent soft tissue bone marrow contrast resolution has a significant role in surgical planning and limb preservation. Ultrasound and US-guided aspiration has recently been involved in the diagnosis and management of osteomyelitis with several advantages particularly in children. Our goal in this review is to outline the ability of various imaging techniques by comparing their strengths and weaknesses in the diagnosis of osteomyelitis. Finally, we suggest various imaging algorithms for specific clinical scenarios. Spondylitis and septic arthritis are not discussed in this review.

Contrast media and metformin: guidelines to diminish the risk of lactic acidosis in non-insulin-dependent diabetics after administration of contrast media. ESUR Contrast Media Safety Committee.

Abstract: The purpose of this study was to establish guidelines on how to avoid metformin-induced lactic acidosis following intravascular use of contrast me- dia. We reviewed articles published in international journals. No conclusive evidence was found to indi- cate that the intravascular use of contrast media pre- cipitated the development of metformin-induced lac- tic acidosis in patients with normal S-creatinine ( < 130 mmol/l). The complication was almost always observed in non-insulin-dependent diabetic patients with decreased renal function before injection of con- trast media. Guidelines for the use of contrast media in this group of patients are proposed.

Pediatric liver neoplasms: a radiologic-pathologic correlation.

Abstract: Only 1-2 % of all pediatric tumors occur in the liver. Two thirds of these tumors are malignant and almost all of the tumors cause clinical symptoms due to their mass effects. Besides the poor prognosis in most of the malignant tumors, for further treatment the origin and nature of the neoplasm has to be known. Due to the mostly unimpeded growth into the peritoneal cavity, the origin of the tumors is primarily often unclear and can non-invasively only be determined by advanced imaging techniques. The display of the macro- and microhistological key features of primary pediatric liver neoplasms, including hepatoblastoma (HB), infantile hemangioendothelioma (IHE), mesenchymal hamartoma (MH), undifferentiated (embryonal) sarcoma (UES), and hepatocellular carcinoma (HCC), together with their imaging representation by ultrasound, computed tomography, and magnetic resonance imaging, may deepen the understanding of the underlying pathology and its imaging appearance. Furthermore, in many cases sufficient information may be provided not only to differentiate benign from malignant tumors, but also to guide for adequate treatment.

MRI with an endorectal coil for staging of clinically localised prostate cancer prior to radical prostatectomy.

Abstract: The purpose of this study was to evaluate the ability of MR imaging with an endorectal coil (erMRI) to predict the local pathological stage of prostatic carcinoma prior to radical prostatectomy. Thirty-one consecutive patients (median age 61 years, range 40–71 years) with clinically localised prostate cancer were assessed preoperatively by endorectal MRI (at 1.0 T). The pulse sequences consisted of fast spin-echo axial and coronal T2-weighted images and inversion recovery with two echoes for axial fat-suppressed images. The assessment of tumour stage and measurement of tumour dimension by erMRI were compared with the corresponding findings on whole-mount step sections of the surgical specimens. Postoperatively, 14 of the 31 patients (45 %) were found to have extracapsular extension, 7 with capsular penetration (CP) only, and 7 had a combination of CP and seminal vesicle invasion (SVI). Capsular penetration was detected by erMRI with a sensitivity of 0.71 and specificity of 0.47, whereas the sensitivity for SVI detection was 0.71 and the specificity 0.83. Endorectal MRI for staging clinically localised prostatic carcinoma gives a good prediction of invasion of the seminal vesicles but is unreliable in predicting capsular penetration.

Kinematic CT and MR imaging of the patellofemoral joint.

Abstract: Anterior knee pain is a frequently encountered orthopedic symptom and is often associated with patellofemoral malalignment, which may cause chondromalacia of the patella. The difficulty in determining the patellar position between 0 ° and 30 ° of knee flexion with a conventional axial radiographic examination is well known. The introduction of computed tomography (CT) and magnetic resonance (MR) imaging for the diagnosis of knee joint abnormalities has enabled assessment of the patellar position in this critical range. More recently, emphasis has been placed on dynamic visualization of patellar motion to detect an abnormal tracking pattern. The important influence of the quadriceps muscle on the patellar tracking pattern is well known and has been examined during active knee extension by the use of ultrafast CT, and motion-triggered and ultrafast MR imaging. This article provides an overview of the current status of kinematic CT and MR imaging in the diagnosis of patellofemoral alignment, its clinical implications, and future directions.

Injuries of the lateral collateral ligaments of the ankle: assessment with MR imaging

Abstract: The aim of this study was to evaluate the ability of MRI to display injuries of the lateral collateral ligamentous complex in patients with an acute ankle distorsion trauma. The MR examinations of 36 patients with ankle pain after ankle distorsion were evaluated retrospectively without knowledge of clinical history, outcome and/or operative findings. The examinations were performed on a 1.5-T whole-body imager using a flexible surface coil. The signs for ligamentous abnormality were as follows: complete or partial discontinuity, increased signal within, and irregularity and waviness of the ligament. The results were compared with operative findings in 18 patients with subsequent surgical repair. Eighteen patients with conservative therapy had a follow-up MR examination after 3 months. There was 1 sprain, 3 partial and 32 complete tears of the anterior talofibular ligament, and 5 sprains, 5 partial, and 7 complete tears of the calcaneofibular ligament. There were no lesions of the posterior talofibular ligament. Compared with surgery, MRI demonstrated in 18 of 18 cases the exact extent of anterior talofibular ligament injuries and underestimated the extent in 2 of 8 cases of calcaneofibular ligament injury. In patients with follow-up MRI after conservative therapy, a thickened band-like structure was found along the course of the injured ligament in 17 of 18 cases. The absence of ligament repair after conservative treatment was confirmed during operative revision in one case. The MRI technique allows for grading of the extent of injury of the lateral collateral ligamentous complex after acute ankle strain. It seems to be suitable for monitoring the healing process after conservative-functional treatment of ligament tears.

Bone mineral density in adults with Down's syndrome

Abstract: The objective of the study was to elucidate if individuals with Down's syndrome (DS) are likely to experience an increased risk of osteoporosis with advancing age, in addition to precocious aging and their skeletal anomalies. Bone mineral density (BMD) was measured in 22 home-reared adults (9 males and 13 females; age 26.22 +/- 4.45 and 23.65 +/- 3.23 years, respectively) by dual energy X-ray absorptiometry (DXA). The BMD of the second to fourth lumbar vertebrae was measured in posteroanterior projection and the mean density expressed as grams per square centimetre. The BMD of DS individuals was compared with 27 control subjects (12 males and 15 females) of the same age (age 24.16 +/- 3.46 and 23.86 +/- 2.92 years, respectively). The results showed that the BMD of the lumbar spine in the males as well as in the females with DS was significantly lower than that in their control counter-parts (p < 0.001). Comparing the DS males with the females, the BMD was lower in the males at a level of 9%. Factors that contribute to this disorder may be mainly the muscular hypotonia, the sedentary life-style and the accompanying diseases which frequently observed in the syndrome. Future studies must be focused on the biochemistry of bone metabolism, the evaluation of gonadal, thyroid and parathyroid function, and the genes of the extra chromosome 21.

Contrast mechanisms in MR imaging.

Abstract: This paper is a brief introduction to tissue-specific parameters and the utilization of various MR imaging sequences to display these parameters in order to differentiate normal from pathologic tissue and function. The three dominant tissue-specific parameters discussed are proton density, longitudinal relaxation time T1, and transverse relaxation time T2. For the utilization of gradient-echo sequences, transverse relaxation time T2* is introduced, more dependent on the environment or tissue interfaces than on the tissue itself. Another tissue-specific parameter is the concentration of macromolecules and their hydration layers as targeted with magnetization transfer imaging. Still another tissue-specific parameter is the chemical environment. Functional parameters that influence the contrast are diffusion, perfusion, flow, or motion. The sequence-related utilization of these tissue-specific parameters start with magnetization preparation as in spectral suppression of fat signal, relaxation-dependent elimination of fat or cerebrospinal fluid (CSF) signal, simple inversion pulse, magnetization transfer saturation, or diffusion weighting. Possible contrast mechanisms for the tissue-specific parameters are discussed for each of the commonly used sequences, whether of spin-echo type or of gradient-echo type, with or without magnetization preparation, conventional single-echo acquisition, or contemporary multiecho acquisition.

Gadolinium dimeglumine: an alternative contrast agent for digital subtraction angiography.

Abstract: The aim of this study was to evaluate gadolinium diethylenetriaminepenta-acetic acid (Gd-DTPA) as an alternative contrast agent for digital subtraction angiography (DSA) in patients with renal insufficiency or previous anaphylactic reaction to iodinated contrast agents. We performed 34 DSAs in 31 patients by use of the commercially available 0.5-M Gd-DTPA solution (Magnevist, Schering, Berlin, Germany). The contrast material was power- or hand-injected at the same rate as iodinated contrast material, without exceeding a total amount of 0.4 mmol/kg body weight. In 18 studies Gd-DTPA was the sole contrast agent. In 9 cases gadolinium injections were combined with carbon dioxide. Restricted non-ionic contrast medium injections were administered to complete the examinations in 7 cases and for comparative purposes in 1 case. Cerebral and carotid arteries, one superior limb, abdominal aorta, renal arteries, renal transplants, iliac arteries and inferior limbs were imaged, and ten endovascular interventional procedures, including three transjugular intrahepatic percutaneous stent shunts, were performed. No side effects were observed. Diagnostic angiographic images were obtained in all cases except in 5 of the 8 distal run-off studies. Gadolinium-based contrast can produce clinically useful angiograms in patients with a contra-indication to iodine who must undergo angiography.

Nipple discharge disorders: current diagnostic management and the role of fiber-ductoscopy.

Abstract: Nipple discharge disorders is a field in which there has been both increasing awareness on the part of patients and advances in management. Today secretion from nipples can be classified according to its color, cellularity and biology. To be significant a discharge should be true, spontaneous, persistent and non-lactational. Moreover there are methods to differentiate patients who require surgical intervention from those who do not. Surgically significant nipple discharges are watery, serous (yellow), serosanguineous and bloody. Cytology smears of discharge material have helped to classify the cellular material, providing information about normality, atypia and malignancy and also about papillary formation of the exfoliated cells. Tests such as Hemoccult help to discover occult blood in the secreted fluid. Modern immunological tests can be performed on cytology smears where occurrence of high levels of carcinoembryonic antigen could indicate a latent malignancy. Galactography investigation is today the state-of-the-art approach to investigate patients with nipple discharge disorders and this examination can demonstrate the size, location and extent of an intraductal abnormality. Modern high-resolution ultrasound techniques are helpful in visualizing intraductal disorders and are becoming a good complementary approach if not an alternative to traditional radiology techniques. Recently even MR galactography has been shown to be of diagnostic value, but not as informative as regular galactography. The most sophisticated investigation method, which can also be used therapeutically, is fiber-ductoscopy of the concerned duct in a breast. This technique, although expensive and in its infancy, is a fascinating and promising approach for inspecting the intraductal lumina. In this article the background, current investigation methods and possibilities of the technique are described, as well as the most sophisticated ways to deal with nipple discharge disorders in human breasts.

Anatomic variation in the origin of the main renal arteries: spiral CTA evaluation.

Abstract: The aim of this study was to provide quantitative data on the origin and trajectory of the main renal arteries using spiral CT angiography and arteriography. Normal renal artery anatomy was assessed on spiral CT angiography (axial transverse sections and shaded-surface-display reconstructions) in 100 patients referred for renal arteriography who had no significant renal artery stenosis. Two hundred major renal arteries were studied. The vast majority of right (88 %) and left (87 %) renal arteries originated between the lower third of the first lumbar vertebra and the lower border of the second lumbar vertebra. In 50 patients both ostia were at the same level; in the remaining 50 patients, the right ostium was located above the left in 37 patients. On the right, the angle of origin varied from –10 to + 55 ° (mean + 24 °). On the left, the angle of origin varied from + 30 to –55 ° (mean –11 °). Spiral CT angiography provides additional anatomic data, notably regarding the angle of origin of the renal arteries, that is potentially useful for planning interventional procedures.