Purpose
To evaluate whether MR scanners with acoustic noise reduction and a short magnetic bore reduce the rate of claustrophobic reactions.

Materials and Methods
We performed a cohort study in an outpatient setting, enrolling a total of 55,734 consecutive patients referred for MRI of any part of the body based on a clinical indication. Imaging was performed using a conventional MR scanner (42,998 patients) and a recently developed MR scanner (12,736 patients) with 97% acoustic noise reduction and a short bore. Multiple logistic regression analysis was used to adjust for the nonrandomized design.

Results
In addition to those undergoing head-first examinations, female and middle-aged patients were significantly more likely to develop claustrophobia in the logistic regression analysis (P < 0.001). The rate of claustrophobic reactions was significantly lower with the recent MR scanner (0.7%; 95% confidence interval [CI]: 0.6–0.9%) than with the conventional scanner (2.1%; 95% CI, 2.0–2.3%; P < 0.001) with an adjusted odds ratio (OR) of 3.1 (95% CI, 2.5–3.9) and a number needed to treat of 72 (95% CI, 63–85).

Conclusion
The incidence of claustrophobia may be reduced by a factor of 3 when recently-developed MR scanners are used. J. Magn. Reson. Imaging 2007;26:1322–1327. © 2007 Wiley-Liss, Inc.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/jmri.21147

Claustrophobia during magnetic resonance imaging: Cohort study in over 55,000 patients

Hepatic tumors in children.

Our study results suggest that there may be a large group of women at elevated risk of breast cancer for whom MR imaging would not be acceptable; for these women, supplemental screening with US combined with mammography could be considered.

Reasons women at elevated risk of breast cancer refuse breast MR imaging screening: ACRIN 6666.

Mesenchymal hamartoma of the liver: a systematic review

Purpose
To evaluate the incidence of MRI-related claustrophobia and prematurely terminated MRI (ptMRI) examinations due to claustrophobia in a large-scale cohort study.

Materials and Methods
The hospital's computerized radiology information system (RIS) was retrospectively analyzed for all 1.5-Tesla MRI examinations and reports during the year 2004. Data collected included demographic information, body part examined, known claustrophobia, and whether the examination was prematurely terminated. All information available on the MRI examinations and the patient-based data (i.e., excluding any additional examinations per patient) were analyzed.

Results
A total of 5798 MRI reports of 4821 patients were evaluated. A total of 95 patients (1.97%) suffered from claustrophobia and 59 (1.22%) prematurely terminated the examination due to claustrophobia. The incidence of ptMRI was higher in women than men (no statistical significance). The majority of patients with ptMRI were between 20 and 80 years old. Patients undergoing head MRI showed the highest incidence of ptMRI and those undergoing extremity, breast, or pelvic MRI had the lowest. Prone compared to supine positioning results in the lowest ptMRI incidence (P < 0.05).

Conclusion
Claustrophobic reactions cause a relatively low incidence of ptMRI and are influenced by sex, body part examined, and positioning within the MR scanner. Sedation and prone positioning might help overcome these reactions. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jmri.21012

Claustrophobia and Premature Termination of Magnetic Resonance Imaging Examinations

Malignant transformation of mesenchymal hamartoma of the liver : case report and review of the literature

A recognized cause of incomplete or cancelled MRI examinations is anxiety and claustrophobic symptoms in patients undergoing MR scanning. This appears to be a problem in many MRI centres in Western Europe and North America, where it is said to be costly in terms of loss of valuable scan time, and has led to researchers suggesting several anxiety-reducing approaches for MRI. To determine the incidence of failed MRI examination among our patients and if there are any associations with a patient's sex, age and education level, we studied claustrophobia that led to premature termination of the MRI examination in the University Malaya Medical Centre (UMMC) in 3324 patients over 28 months. The incidence of failed MRI examinations due to claustrophobia in the UMMC was found to be only 0.54%. There are associations between claustrophobia in MRI with the patients' sex, age and level of education. The majority of those affected were male patients and young patients in the 25-45-years age group. The patients' education level appears to be the strongest association with failed MRI examinations due to claustrophobia, where the majority of the affected were highly educated individuals. Claustrophobia in MRI is more of a problem among the educated individuals or patients from a higher socio-economic group, which may explain the higher incidence in Western European and North American patients.

Failed magnetic resonance imaging examinations due to claustrophobia.

Objective: To determine the effective radiation dose and image quality resulting from 100 versus 120 kilovoltage (kV) protocols among patients referred for computed tomography pulmonary angiography (CTPA). Materials and methods: Sixty-six patients with clinical suspicion of pulmonary embolism (PE) were prospectively enrolled. Two CTPA protocols (group A: n=33, 100 kV/115 mAs; group B: n=33, 120 kV/90 mAs) were compared. Two experienced radiologists assessed image quality in terms of diagnostic performance and effect of artefacts. Image quality parameters [CT attenuation, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR)] and effective radiation dose between the two protocols were compared. Results: The contrast enhancement in central and peripheral pulmonary arteries was significantly higher in group A than in group B (P Conclusions: Reducing the tube voltage from 120 to 100 kV in CTPA allows a significant reduction of radiation dose without significant loss of diagnostic image quality.

https://qims.amegroups.com/article/download/6468/8468

Use of 100 kV versus 120 kV in computed tomography pulmonary angiography in the detection of pulmonary embolism: effect on radiation dose and image quality

PURPOSE To compare the image quality of the low-dose to the standard-dose protocol of MDCT scanning of the paranasal sinuses, based on subjective assessment and determine the radiation doses to the eyes and thyroid gland and dose reduction between these two protocols. MATERIALS AND METHODS 31 adult patients were scanned. Prior to scanning, thermoluminescent dosimeters (TLDs) were placed at 4 sites: outer canthus of right eye, outer canthus of left eye, inner canthus and anterior neck (thyroid gland). Every patient was scanned twice using the standard-dose protocol (100mAs) followed by the low-dose protocol (40mAs). The images were reviewed by 3 radiologists. Wilcoxon test was used as the test of significance for the image quality assessments. The paired sample t-test was used as the test of significance for the analysis of the radiation doses measured by the TLDs. RESULTS Of the 30 patients selected for analysis, this study showed no significant difference in the scores for the diagnostic image quality and the anatomical structures assessments between the two protocols. The average calculated mean entrance surface doses and standard deviation for the standard-dose and low-dose protocols were 12.40±1.39 mGy and 5.53±0.82 mGy respectively to the lens and 1.03±0.55 mGy and 0.63±0.53 mGy respectively to the thyroid gland. CONCLUSION The reduction of mAs from 100 to 40 resulted in a significant reduction of the radiation doses to the lens and thyroid gland by 55.4% and 38.8% respectively without causing any significant effect to the diagnostic image quality and assessment of the anatomical structures.

/pdf/a-comparison-between-low-dose-and-standard-dose-non-21fy1qtlf5.pdf

A comparison between low-dose and standard-dose non-contrasted multidetector CT scanning of the paranasal sinuses

Objective: To evaluate the septation, wall thickness, and relationship of the sphenoid sinuses to the internal carotid arteries on computed tomography. Methods: Seventy patients with normal sphenoid sinuses were evaluated. Scans were done in both axial and coronal planes. The number of septations of the sphenoid sinuses was analysed, along with the incidence of septa directly related to the internal carotid arteries. The thickness of the bony wall of the sphenoid sinus adjacent to the internal carotid arteries was also measured. Results: Significantly more septa were noted on the coronal than on the axial view. Septa were not directly related to one or other internal carotid artery in the majority of patients (68.6%). Septa were directly related to the right internal carotid artery in 13 patients (18.6%), and to the left internal carotid artery in nine patients (12.9%). The bony wall thickness of the sphenoid sinuses adjacent to the internal carotid arteries ranged from 0.4 mm to 1.7 mm. There was no significant difference in wall measurements between the right and left sides. Conclusion: This study highlights the anatomy, variants, and the relationship of the internal carotid arteries to the sphenoid sinuses. Sphenoid septations were better demonstrated on coronal plane views.

The Sphenoid sinuses: Computed Tomographic Assessment of Septation, Relationship to the internal carotid arteries, and sidewall thickness in the Malaysian Population

G Kumar

Papers

Malignant transformation of mesenchymal hamartoma of the liver : case report and review of the literature

Failed magnetic resonance imaging examinations due to claustrophobia.

Use of 100 kV versus 120 kV in computed tomography pulmonary angiography in the detection of pulmonary embolism: effect on radiation dose and image quality

A comparison between low-dose and standard-dose non-contrasted multidetector CT scanning of the paranasal sinuses

The Sphenoid sinuses: Computed Tomographic Assessment of Septation, Relationship to the internal carotid arteries, and sidewall thickness in the Malaysian Population