Magnetic nanoparticles have attracted attention because of their current and potential usefulness as contrast agents for magnetic resonance imaging (MRI) or colloidal mediators for cancer magnetic hyperthermia. This review examines these in vivo applications through an understanding of the involved problems and the current and future possibilities for resolving them. A special emphasis is made on magnetic nanoparticle requirements from a physical viewpoint (e.g. relaxivity for MRI and specific absorption rate for hyperthermia), the factors affecting their biodistribution (e.g. size, surface hydrophobic/hydrophilic balance, etc.) and the solutions envisaged for enhancing their half-life in the blood compartment and targeting tumour cells.

http://konsys-t.tanger.cz/files/proceedings/nanocon_11/lists/papers/1094.pdf

Magnetic nanoparticle design for medical diagnosis and therapy

Magnetic resonance imaging (2)

There have been few fundamental improvements in clinical X-ray contrast agents in more than 25 years, and the chemical platform of tri-iodobenzene has not changed. Current agents impose serious limitations on medical imaging: short imaging times, the need for catheterization in many cases, occasional renal toxicity, and poor contrast in large patients. This report is the first demonstration that gold nanoparticles may overcome these limitations. Gold has higher absorption than iodine with less bone and tissue interference achieving better contrast with lower X-ray dose. Nanoparticles clear the blood more slowly than iodine agents, permitting longer imaging times. Gold nanoparticles, 1.9 nm in diameter, were injected intravenously into mice and images recorded over time with a standard mammography unit. Gold biodistribution was measured by atomic absorption. Retention in liver and spleen was low with elimination by the kidneys. Organs such as kidneys and tumours were seen with unusual clarity and high spatial resolution. Blood vessels less than 100 mm in diameter were delineated, thus enabling in vivo vascular casting. Regions of increased vascularization and angiogenesis could be distinguished. With 10 mg Au ml 21 initially in the blood, mouse behaviour was unremarkable and neither blood plasma analytes nor organ histology revealed any evidence of toxicity 11 days and 30 days after injection. Gold nanoparticles can be used as X-ray contrast agents with properties that overcome some significant limitations of iodine-based agents.

/pdf/gold-nanoparticles-a-new-x-ray-contrast-agent-3nrxuskv5q.pdf

Gold nanoparticles: a new X-ray contrast agent

Methods for Staging Non-small Cell Lung Cancer: Diagnosis and Management of Lung Cancer, 3rd ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

This review offers a critical analysis of the state of the art of medical microbubbles and their application in therapeutic delivery and monitoring. When driven by an ultrasonic pulse, these small gas bubbles oscillate with a wall velocity on the order of tens to hundreds of meters per second and can be deflected to a vessel wall or fragmented into particles on the order of nanometers. While single-session molecular imaging of multiple targets is difficult with affinity-based strategies employed in some other imaging modalities, microbubble fragmentation facilitates such studies. Similarly, a focused ultrasound beam can be used to disrupt delivery vehicles and blood vessel walls, offering the opportunity to locally deliver a drug or gene. Clinical translation of these vehicles will require that current challenges be overcome, where these challenges include rapid clearance and low payload. The technology, early successes with drug and gene delivery, and potential clinical applications are reviewed.

Ultrasound microbubble contrast agents: fundamentals and application to gene and drug delivery.

Computed tomography has become an important diagnostic modality in the preoperative staging of patients with bronchogenic carcinoma. The adrenal glands represent one of the most frequent sites of metastasis. Therefore, an isolated adrenal mass discovered on preoperative thoracoabdominal CT poses a diagnostic problem. Three hundred thirty patients with histologically proved nonsmall-cell bronchogenic carcinoma were evaluated. Thirty-two had adrenal masses without further evidence of disease in the abdomen. Eight of these 32 masses were metastases, 17 were proved adenomas, and seven did not undergo biopsy. Thus, in the patients with nonsmall-cell bronchogenic carcinoma, an isolated adrenal mass is more likely benign than metastatic, and biopsy is advocated prior to withholding potentially curative surgery.

Isolated adrenal masses in nonsmall-cell bronchogenic carcinoma.

Forty-three patients with known primary or secondary neoplastic involvement of the liver underwent evaluation to determine the number, size, and location of focal lesions before possible tumor resection. Imaging studies included computed tomography (CT) during arterial portography (CTAP), delayed CT, and magnetic resonance (MR) imaging at various pulse sequences. Results of radiologic studies were compared with surgical and pathologic findings. In the combined group of surgical and nonsurgical patients, CTAP was significantly more sensitive (85%) than all other techniques except 1.5-T T2-weighted spin-echo imaging (64%). Combining the information from all MR pulse sequences yielded a cumulative sensitivity of 68%. Combining the information from two modalities yielded sensitivity of 96% for CTAP plus MR imaging, 85% for CTAP plus delayed CT, and 77% for delayed CT plus MR imaging. The authors conclude that when it is vital to know the precise number, size, and location of focal hepatic lesions before tumor...

Hepatic tumors: comparison of CT during arterial portography, delayed CT, and MR imaging for preoperative evaluation.

PURPOSE: To evaluate prospectively the diagnostic accuracy of non-enhanced and gadolinium-enhanced magnetic resonance (MR) imaging in characterization of hepatic lesions. MATERIALS AND METHODS: Fifty-five patients with benign and 52 patients with malignant focal liver lesions underwent examination at 1.5 T that comprised nonenhanced and dynamic contrast material-enhanced images. Four experienced radiologists independently read the different sets of images without and with knowledge of clinical history. RESULTS: Receiver operating characteristic analysis showed that dynamic contrast-enhanced MR imaging added information to nonenhanced MR studies and thereby improved distinction between benign and malignant lesions (P < .05). Knowledge of clinical data further improved lesion characterization with nonenhanced and combined nonenhanced and contrast-enhanced MR imaging (P < .05). CONCLUSION: Dynamic contrast-enhanced MR imaging is a useful adjunct for characterization of hepatic lesions. Knowledge of clinical ...

Focal liver lesions: characterization with nonenhanced and dynamic contrast material-enhanced MR imaging.

The purpose of our study was to determine the frequency of detection of small hepatic lesions (less than or equal to 15 mm) in outpatients who had abdominal CT and to assess the significance of these lesions in the presence or absence of known malignant tumors. Contrast-enhanced abdominal CT scans in 1454 patients were reviewed. In 254 patients (17%), hepatic lesions 15 mm or smaller were detected. In 51% of these patients, lesions were judged benign on the basis of other imaging studies, biopsy results, or stability for at least 6 months as shown by CT. Lesions were judged malignant on the basis of progression seen on radiologic studies or biopsy in 22%. The other 27% of the patients had lesions that could not be classified. The majority of patients with small hepatic lesions (82%) were known to have a malignant tumor; in 51% of these patients, lesions were diagnosed as benign. No patient without a known malignant tumor had a small hepatic lesion that was determined to be malignant. Multiple small lesions were more likely to represent malignant disease than were single small lesions. We conclude that small hepatic lesions are common (seen in 17% of our patients), and that there is a high probability that hepatic lesions smaller than 15 mm are benign, even in patients known to have an extrahepatic malignant tumor.

The frequency and significance of small (less than or equal to 15 mm) hepatic lesions detected by CT.

Fifty-eight percutaneous needle biopsies of adrenal masses were performed in 53 patients. The technique was initially successful in 44 (83%) of 53 patients. Five patients had second procedures because of initial failure or the possibility of sampling error. Fourteen biopsies were performed in nononcologic patients and 39 in patients with a known malignancy. None of the adrenal masses in nononcologic patients were malignant. Only 18 (46.1%) of the 39 masses in oncologic patients were metastases; the rest represented a variety of nonneoplastic conditions. Seven minor complications occurred in six patients. Two of these patients required transfusions for hypotension or decreases in hematocrit. No correlation was noted between needle size and complications. There were no pneumothoraces. The procedure is an accurate and safe alternative to surgical biopsy.

https://www.ajronline.org/doi/pdfplus/10.2214/ajr.144.1.67

Michael E. Bernardino

Papers

Isolated adrenal masses in nonsmall-cell bronchogenic carcinoma.

Hepatic tumors: comparison of CT during arterial portography, delayed CT, and MR imaging for preoperative evaluation.

Focal liver lesions: characterization with nonenhanced and dynamic contrast material-enhanced MR imaging.

The frequency and significance of small (less than or equal to 15 mm) hepatic lesions detected by CT.

CT-guided adrenal biopsy: accuracy, safety, and indications.