Does Extended PET Acquisition in PET/MRI Rectal Cancer Staging Improve Results?

OBJECTIVE: The purpose of this study was to determine if extended PET acquisition times in the pelvis during PET/MRI increase detection rates of potentially metastatic lymph nodes in patients with rectal cancer. MATERIALS AND METHODS: Our study was approved by the institutional review board of the University of California, San Francisco. Twenty-two patients with biopsy-proven rectal cancer underwent imaging via simultaneous 3-T time-of-flight PET/MRI, with seven undergoing two separate PET/MRI examinations, for a total of 29 studies. Each examination included both a whole-body PET/MRI and a dedicated pelvic PET/MRI with both 3- and 15-minute PET acquisitions for the pelvis. Three radiologists interpreted each examination with PET only, MRI only, then combined PET and MRI examinations, using all available images. Additionally, the 3- and 15-minute PET acquisitions of the pelvis were reviewed separately by a single radiologist. RESULTS: A total of 94 lymph nodes were identified as abnormal on PET, all with MRI anatomic correlates. Of these, 37 (39.4%) were seen only on the dedicated 15-minute acquisition. Fifty-seven (60.6%) nodes measured 5 mm or less, including 29 (30.9%) seen only on the 15-minute acquisition. Thirty-one (33.0%) nodes measured 5.1-10 mm, including eight (25.8%) seen only on the 15-minute acquisition. Of the 17 subjects imaged for initial staging, 11 (64.7%) were upstaged as a result of the increased PET acquisition time (10 from N1 to N2 and one from N0 to N1). CONCLUSION: Longer PET acquisition times during PET/MRI for rectal cancer increases the number of FDG-avid lymph nodes detected without increasing scan time.

The Stability of Factors Influencing the Choice of Medical Specialty Among Medical Students and Postgraduate Radiology Trainees.

OBJECTIVE: To investigate whether general psychological motivating factors that guide career selection of a medical specialty differ over the course of medical school and to compare differences in motivating factors among students choosing "controllable" lifestyle specialties, students choosing "uncontrollable" lifestyle specialties, and a cohort of radiology residents. MATERIALS AND METHODS: An anonymous survey was distributed to first- through fourth-year medical students and radiology residents at a single institution. Participants were asked to select their top three of seven factors that most influenced their choice of medical specialty. Fourth-year students were asked to designate the specialty to which they had applied. RESULTS: The survey was distributed to 259 students and 47 radiology residents with a response rate of 93.8% (243 of 259) and 95.7% (45 of 47), respectively. The top three factors indicated by medical students were finding the daily work fulfilling, work-life balance, and interest in the subject. These top three factors were common to all medical student classes and did not differ between students choosing "controllable" versus "uncontrollable" fields. The factors uncommonly selected were similar personality to others in the field, attending income, competitiveness or prestige, and job market conditions. For radiology residents, the top three motivating factors were the same as for medical students. CONCLUSION: Three out of seven motivating factors were universally important to trainees, regardless of their stage of medical training or their selection of a controllable versus uncontrollable lifestyle specialty. These data suggest the variety of career choices made by students may not derive from differing underlying values.

PI-RADS v2 and ADC values: is there room for improvement?

PURPOSE: To determine the diagnostic accuracy of ADC values in combination with PI-RADS v2 for the diagnosis of clinically significant prostate cancer (CS-PCa) compared to PI-RADS v2 alone. MATERIALS AND METHODS: This retrospective study included 155 men whom underwent 3-Tesla prostate MRI and subsequent MR/US fusion biopsies at a single non-academic center from 11/2014 to 3/2016. All scans were performed with a surface coil and included T2, diffusion-weighted, and dynamic contrast-enhanced sequences. Suspicious findings were classified using Prostate Imaging Reporting and Data System (PI-RADS) v2 and targeted using MR/US fusion biopsies. Mixed-effect logistic regression analyses were used to determine the ability of PIRADS v2 alone and combined with ADC values to predict CS-PCa. As ADC categories are more practical in clinical situations than numeric values, an additional model with ADC categories of ≤ 800 and > 800 was performed. RESULTS: A total of 243 suspicious lesions were included, 69 of which were CS-PCa, 34 were Gleason score 3+3 PCa, and 140 were negative. The overall PIRADS v2 score, ADC values, and ADC categories are independent statistically significant predictors of CS-PCa (p < 0.001). However, the area under the ROC of PIRADS v2 alone and PIRADS v2 with ADC categories are significantly different in both peripheral and transition zone lesions (p = 0.026 and p = 0.03, respectively) Further analysis of the ROC curves also shows that the main benefit of utilizing ADC values or categories is better discrimination of PI-RADS v2 4 lesions. CONCLUSION: ADC values and categories help to diagnose CS-PCa when lesions are assigned a PI-RADS v2 score of 4.

Evaluating the performance of PI-RADS v2 in the non-academic setting.

PURPOSE: To evaluate the utility of PI-RADS v2 to diagnose clinically significant prostate cancer (CS-PCa) with magnetic resonance ultrasound (MR/US) fusion-guided prostate biopsies in the non-academic setting. MATERIALS/METHODS: Retrospective analysis of men whom underwent prostate multiparametric MRI and subsequent MR/US fusion biopsies at a single non-academic center from 11/2014 to 3/2016. Prostate MRIs were performed on a 3-Tesla scanner with a surface body coil. The Prostate Imaging Reporting and Data System (PI-RADS) v2 scoring algorithm was utilized and MR/US fusion biopsies were performed in selected cases. Mixed effect logistic regression analyses and receiver-operating characteristic (ROC) curves were performed on PI-RADS v2 alone and combined with PSA density (PSAD) to predict CS-PCa. RESULTS: 170 patients underwent prostate MRI with 282 PI-RADS lesions. MR/US fusion diagnosed 71 CS-PCa, 33 Gleason score 3+3, and 168 negative. PI-RADS v2 score is a statistically significant predictor of CS-PCa (P < 0.001). For each one-point increase in the overall PI-RADS v2 score, the odds of having CS-PCa increases by 4.2 (95% CI 2.2-8.3). The area under the ROC curve for PI-RADS v2 is 0.69 (95% CI 0.63-0.76) and for PI-RADS v2 + PSAD is 0.76 (95% CI 0.69-0.82), statistically higher than PI-RADS v2 alone (P < 0.001). The rate of CS-PCa was about twice higher in men with high PSAD (≥0.15) compared to men with low PSAD (<0.15) when a PI-RADS 4 or 5 lesion was detected (P = 0.005). CONCLUSION: PI-RADS v2 is a strong predictor of CS-PCa in the non-academic setting and can be further strengthened when utilized with PSA density.

Radiologic assessment of fetal tracheal balloon occlusion.

Fetal endoscopic tracheal occlusion (FETO) is a novel technique to treat cases of isolated severe congenital diaphragmatic hernia (CDH). Although there are benefits of MRI over ultrasound in assessing lung volumes, it is unknown whether there are benefits of MRI for localizing the tracheal balloon. This is a retrospective study reviewing the imaging characteristics of FETO in patients who underwent both MRI and ultrasound exams done to localize tracheal balloons.

CT pulmonary angiography in pregnant and postpartum women: low yield, high dose.

PURPOSE: To compare the diagnostic utility of computed tomography pulmonary angiography (CTPA) in pregnant/postpartum women with age-matched controls. MATERIALS: We performed a retrospective case-control series of pregnant/postpartum women and control women who underwent CTPA from 2008 to 2011. RESULTS: The study included 34 pregnant women, 16 postpartum women, and 50 controls. CTPAs were positive in 2% of pregnant/postpartum women and 16% of controls (P=.003). The main pulmonary artery mean opacification was 271 Hounsfield units (HU) for pregnant/postpartum women vs. 303 HU (P=.12). Radiation exposure was high in both groups but lower in pregnant/postpartum women, 10 vs. 14 mSv (P=.003). CONCLUSION: CTPA in pregnant and postpartum women had low yield and remained high dose.