PI-RADS Committee Position on MRI Without Contrast Medium in Biopsy-Naive Men With Suspected Prostate Cancer: Narrative Review.

The steadily increasing demand for diagnostic prostate MRI has led to concerns regarding the lack of access to and the availability of qualified MRI scanners and sufficiently experienced radiologists, radiographers, and technologists to meet the demand. Solutions must enhance operational benefits without compromising diagnostic performance, quality, and delivery of service. Solutions should also mitigate risks such as decreased reader confidence and referrer engagement. One approach may be the implementation of MRI without the use gadolinium-based contrast medium (bipara-metric MRI), but only if certain prerequisites such as high-quality imaging, expert interpretation quality, and availability of patient recall or on-table monitoring are mandated. Alternatively, or in combination, a clinical risk-based approach could be used for protocol selection, specifically, which biopsy-naive men need MRI with contrast medium (multiparametric MRI). There is a need for prospective studies in which biopsy decisions are made according to MRI without contrast enhancement. Such studies must define clinical and operational benefits and identify which patient groups can be scanned successfully without contrast enhancement. These higher-quality data are needed before the Prostate Imaging Reporting and Data System (PI-RADS) Committee can make evidence-based recommendations about MRI without contrast enhancement as an initial diagnostic approach for prostate cancer workup.

Unenhanced MRI as an Alternative to 99mTc-Labeled Dimercaptosuccinic Acid Scintigraphy in the Detection of Pediatric Renal Scarring.

OBJECTIVE: The purpose of this study was to determine whether unenhanced MRI without sedation is a feasible substitute for dimercaptosuccinic acid (DMSA) scintigraphy in the detection of renal scars in pediatric patients. SUBJECTS AND METHODS: Patients scheduled for 99mTc-labeled DMSA scintigraphy for assessment of possible renal scars were recruited to undergo unenhanced MRI (free-breathing fat-suppressed T2-weighted single-shot turbo spin-echo and T1-weighted gradient-echo imaging, 13 minutes' total imaging time). Scintigraphic and MRI studies were evaluated by two independent blinded specialty-based radiologists. For each imaging examination, readers identified scars in upper, middle, and lower kidney zones and rated their diagnostic confidence and the quality of each study. The scintigraphic readers' consensus score opinion for the presence of scars was considered the reference standard. RESULTS: DMSA scintigraphy showed scarring in 19 of the 78 (24.4%) evaluated zones and MRI in 18 of the 78 (23.1%). The two MRI readers found mean sensitivities of 94.7% and 89.5%, identical specificities of 100%, and diagnostic accuracies of 98.7% and 97.4%. Interobserver agreement was 98.7% for MRI and 92.3% for DMSA scintigraphy. The MRI readers were significantly more confident in determining the absence rather than the presence of scars (p = 0.02). MRI readers were more likely to rate study quality as excellent (84.6%) than were the scintigraphic readers (57.7%) (p = 0.024). CONCLUSION: Unenhanced MRI has excellent sensitivity, specificity, diagnostic accuracy, and interobserver agreement for detecting renal scars in older children who do not need sedation. It may serve as a substitute modality, especially when DMSA is not available.

Unenhanced magnetic resonance imaging immediately after radiofrequency ablation of liver malignancy: preliminary results.

PURPOSE: To assess the accuracy of unenhanced magnetic resonance imaging (MRI) immediately after the percutaneous ultrasound-guided radiofrequency ablation (RFA) of liver malignancy in predicting treatment efficacy at CT follow-up. MATERIALS AND METHODS: Percutaneous ablation was prospectively performed in 23 liver malignancies (20 hepatocarcinomas and 3 metastases). After the procedure in the same day all patients were studied with unenhanced MRI. The best sequence to detect the coagulative necrosis was visually established. Pre-RFA CT and post-RFA MRI were registered with non-rigid transformation algorithm. Manual segmentation of lesions and ablated areas in pre-RFA CT, post-RFA MRI, and follow-up CT were obtained. Sensitivity, specificity, positive predictive value (PPV), negative predicitve value (NPV), and accuracy of MRI in predicting the correct centering and the complete treatment of the lesion were calculated in respect to the 1-month follow-up CT. RESULTS: Fat-saturated T1-weighted (fs T1-w) was the sequence in which the best conspicuity of the ablated area was depicted. Coagulative necrosis was hyperintense in fs T1-w sequence in 17/23 (74%). In respect to follow-up CT, MRI predicted the correct centering of the lesions in 19/20 lesions with sensitivity, specificity, PPV, NPV, and accuracy of 100%, 75%, 95%, 100%, and 100%, respectively. MRI predicted the complete treatment of the lesions in 17/17 lesions with sensitivity, specificity, PPV, NPV, and accuracy of 100%. CONCLUSION: MRI with the single fs T1-w sequence was highly accurate in predicting the treatment efficacy of percutaneous ablation of liver malignancies in comparison to follow-up CT control. Unnecessary CT in case of incomplete treatment can be therefore easily avoided.

What Evidence Is There That Gadobutrol Causes Increasing Signal Intensity within the Dentate Nucleus and Globus Pallidus on Unenhanced T1W MRI in Patients with RRMS?

KEY POINTS : The study by Stojanov et al does not convincingly support the conclusion that gadobutrol causes higher T1 enhancement in brain on unenhanced MRI. The study by Stojanov et al does not rule out confounding factors . The study by Stojanov et al has limitations in study design.

MRI of Labral and Chondral Lesions of the Hip.

OBJECTIVE: Unenhanced MRI, indirect MR arthrography, and direct MR arthrography have been used in the radiologic evaluation of patients with suspected labral tears and chondral lesions of the hip. The purpose of this article is to examine the existing evidence for the use of these techniques in patients with hip pain and suspected labral or chondral abnormalities. CONCLUSION: Evidence from a review of the radiologic literature supports the use of direct MR arthrography over unenhanced MRI and indirect MR arthrography for the detection of labral and cartilage abnormalities in the hip. Although high-resolution unenhanced 3-T MRI appears promising, limited information in the literature supports its use in the detection and characterization of chondrolabral lesions.