Skeletal muscle metastases of the trunk and pelvis: focus on ultrasound, CT findings, and clinical manifestations.

OBJECTIVE: To describe the ultrasound, CT findings, and clinical manifestations of pathologically confirmed skeletal muscle metastases involving trunk and pelvis. METHODS: 71 patients with 71 skeletal muscle metastases of the trunk and pelvis, pathologically proven by ultrasound-guided biopsy, were included in the study, and ultrasound findings were reviewed. CT findings were reviewed for 60 patients who underwent post-contrast CT obtained prior to biopsy, which included skeletal muscle metastases. Medical records, including the type of primary malignancy, presence of coexisting distant metastasis, and method of detection that led to referral for biopsy, were reviewed. RESULTS: Most skeletal muscle metastases were hypoechoic (98.6%) with well-defined margins (85.9%), round-to-oval (47.9%), or lobulated (42.2%) with intralesional vascularity (64.8%). Typical CT findings included abscess-like lesions with rim enhancement (53.3%) or round-to-oval lesions with homogeneous enhancement (40.0%). The most common primary malignancy was lung cancer (49.3%), followed by gastrointestinal cancer (7.0%). Distant metastases other than muscle metastases were found in 84.5% of patients, and coexisting skeletal muscle metastases were found in 47.9%. CT was the most common detection method for metastases (57.8%), being more common than positron emission tomography-CT (22.5%). CONCLUSION: The current study describes the typical imaging findings of skeletal muscle metastases of the trunk and pelvis in patients with advanced cancer. CT may play an important role in the early detection of skeletal muscle metastases, and our results may aid radiologists in their diagnosis. ADVANCES IN KNOWLEDGE: 1. Skeletal muscle metastases of the trunk and pelvis demonstrate typical imaging findings on ultrasound and CT.2. CT may aid in the early detection of skeletal muscle metastases, which are among the rarest, and our results may aid radiologists in their diagnosis.

Juxtaneural ganglia arising from the hip joint: focus on magnetic resonance imaging findings and clinical manifestations.

OBJECTIVE: To present cases of juxtaneural ganglia arising from the hip with a discussion of the magnetic resonance imaging (MRI) findings, presenting symptoms, and possible treatment option. MATERIALS AND METHODS: Two radiologists performed a consensus review of MRI scans obtained between January 2013 and March 2021 to identify patients with juxtaneural ganglia around the hip. A total of 11 patients with 11 juxtaneural ganglia were identified. Medical records and MRI findings were retrospectively reviewed. RESULTS: Eight patients had lesions involving the sciatic nerve, and three patients had lesions involving the obturator nerve. Sciatic ganglia arose from a paralabral cyst in the posteroinferior quadrant and continued through a narrow channel running along the posterior acetabulum, showing increased diameter in the sciatic foramen and intrapelvic portion. Obturator ganglia showed a J- or reverse J-shape on the coronal imaging plane and extended from a paralabral cyst in the anteroinferior quadrant via the obturator canal. Nine patients (9/11, 81.8%) had symptoms resembling those of lumbosacral radiculopathy. Four patients underwent arthroscopic surgery, and one patient underwent ultrasound-guided aspiration, all of whom showed partial improvement. Spontaneous decrease in the extent of the ganglion was observed in three patients (3/11, 27.3%). CONCLUSION: This article describes rare cases of juxtaneural ganglia arising from the hip joint and involving the sciatic and obturator nerves. The lesions share similar MRI findings, and each type of cyst (sciatic or obturator ganglia) involves a specific labral quadrant.

Magnetic Resonance Imaging-Guided Breast Biopsy in Korea: A 10-Year Follow-Up Experience.

PURPOSE: To evaluate the accuracy of magnetic resonance imaging (MRI)-guided breast biopsy. METHODS: We retrospectively reviewed the clinical data of 111 consecutive patients referred for MRI-guided breast biopsy after mammography and breast ultrasound between May 2009 and April 2019. After excluding 37 patients without follow-up images (> 2 years), 74 patients (74 lesions) were finally included. We reviewed the histologic results of MRI-guided biopsy and subsequent surgery, post-biopsy management, and breast cancer development during follow-up. We investigated the false-negative rate, ductal carcinoma in situ (DCIS) underestimation, atypical ductal hyperplasia (ADH) underestimation rate, and technical failure rate of MRI-guided biopsy. RESULTS: Among 74 scheduled MRI-guided biopsies, six were canceled because biopsy was deemed unnecessary, while three failed due to technical difficulties (technical failure rate: 3/68, 4.4%). MRI-guided biopsy was performed in 65 patients, of which 18 patients were diagnosed with malignant lesions, 46 with benign lesions, and one with ADH bordering on DCIS. Subsequent surgery (n = 27) showed DCIS underestimation in three cases (3/7, 43%), ADH underestimation in two cases (1/2, 50%), as well as seven concordant benign and 11 concordant malignant lesions. The overall false-negative rate was 4.3% (2/46). Thirty-eight out of 48 benign lesions were followed-up (median period, 5.8 years; interquartile range, 4.1 years) without subsequent surgery. Thirty-seven concordant benign lesions were stable (n = 27) or disappeared (n = 10); however, the size of one discordant benign lesion increased on follow-up MRI and it was diagnosed as DCIS after 1 year. CONCLUSION: MRI-guided biopsy is an accurate method for exclusion of malignancy with a very low false-negative rate.

Why Is a b-value Range of 1500-2000 s/mm² Optimal for Evaluating Prostatic Index Lesions on Synthetic Diffusion-Weighted Imaging?

OBJECTIVE: It is uncertain why a b-value range of 1500-2000 s/mm² is optimal. This study was aimed at qualitatively and quantitatively analyzing the optimal b-value range of synthetic diffusion-weighted imaging (sDWI) for evaluating prostatic index lesions. MATERIALS AND METHODS: This retrospective study included 92 patients who underwent DWI and targeted biopsy for magnetic resonance imaging (MRI)-suggested index lesions. We generated sDWI at a b-value range of 1000-3000 s/mm² using dedicated software and true DWI data at b-values of 0, 100, and 1000 s/mm². We hypothesized that lesion conspicuity would be best when the background (i.e., MRI-suggested benign prostatic [bP] and periprostatic [pP] regions) signal intensity (SI) is suppressed and becomes homogeneous. To prove this hypothesis, we performed both qualitative and quantitative analyses. For qualitative analysis, two independent readers analyzed the b-value showing the best visual conspicuity of an MRI-suggested index lesion. For quantitative analysis, the readers assessed the b-value showing the same bP and pP region SI. The 95% confidence interval (CI) or interquartile range of qualitatively and quantitatively selected optimal b-values was assessed, and the mean difference between qualitatively and quantitatively selected b-values was investigated. RESULTS: The 95% CIs of optimal b-values from qualitative and quantitative analyses were 1761-1805 s/mm² and 1640-1771 s/mm² (median, 1790 s/mm² vs. 1705 s/mm²; p = 0.003) for reader 1, and 1835-1895 s/mm² and 1705-1841 s/mm² (median, 1872 s/mm² vs. 1763 s/mm²; p = 0.022) for reader 2, respectively. Interquartile ranges of qualitatively and quantitatively selected optimal b-values were 1735-1873 s/mm² and 1573-1867 s/mm² for reader 1, and 1775-1945 s/mm² and 1591-1955 s/mm² for reader 2, respectively. Bland-Altman plots consistently demonstrated a mean difference of less than 100 s/mm² between qualitatively and quantitatively selected optimal b-values. CONCLUSION: b-value range showing a homogeneous background signal may be optimal for evaluating prostatic index lesions on sDWI. Our qualitative and quantitative data consistently recommend b-values of 1500-2000 s/mm².

RF Ablation Versus Cryoablation for Small Perivascular Hepatocellular Carcinoma: Propensity Score Analyses of Mid-Term Outcomes.

PURPOSE: This study aimed to compare radiofrequency (RF) ablation with cryoablation in patients with perivascular hepatocellular carcinoma (HCC) and evaluate the mid-term outcomes of both therapies. MATERIALS AND METHODS: Between January 2015 and April 2018, 111 patients who underwent percutaneous cryoablation (n = 61) or RF ablation (n = 50) for a single perivascular HCC were included. Perivascular HCC was defined as the presence of contacting peritumoral hepatic vessels that were 3 mm or larger in axial diameter. Local tumor progression (LTP) rates were compared by propensity score matching. Procedure-related complications were also assessed. RESULTS: The median follow-up was 23 months (range 2-45 months). Twenty-five patients were matched in each group. The cumulative LTP rates at 1 and 3 years were 8.3% and 17.3% in the cryoablation group and 8.7% and 26.1% in the RF ablation group, with no significant difference (p = 0.379). Although there were no significant differences between the two groups, vascular thrombosis (16.0% vs. 9.8%, p = 0.493) and hepatic infarction (12.0% vs. 3.3%, p = 0.137) more frequently occurred in the RF ablation group than in the cryoablation group. CONCLUSION: In patients with perivascular HCC, cryoablation is an effective alternative treatment compared with RF ablation regarding local tumor control and complications. LEVEL OF EVIDENCE: Level 4 (retrospective case-control study).

Usefulness of noncontrast MRI in differentiation between gallbladder carcinoma and benign conditions manifesting as focal mild wall thickening.

BACKGROUND: Magnetic resonance imaging (MRI) is a reliable imaging tool for evaluating gallbladder carcinoma, but it is costly and time-consuming. PURPOSE: To compare noncontrast MRI with multidetector row CT (MDCT) and gadoxetic acid-enhanced whole MRI in distinguishing gallbladder carcinoma from benign disease. MATERIALS AND METHODS: 101 patients (36 with gallbladder carcinoma and 65 with benign disease) with mild focal gallbladder wall thickening were included. Two radiologists reviewed the MDCT and MRI to determine the differential features between malignancy and benignity. Then, the diagnostic performance of MDCT and MRI (T1-, T2- and diffusion-weighted images) with and without gadoxetic acid enhancement in the diagnosis of gallbladder carcinoma was evaluated. RESULTS: The benign group more often showed T2 necklace sign or T2 hyperintensity within the thickened wall (P < 0.0001) and T1 hyperintensity within the wall or gallbladder lumen (P = 0.0002). Meanwhile, malignancy more frequently showed T2 moderate hyperintensity of the thickened wall, papillary appearance, and diffusion restriction (all P < 0.0001). There were significant differences in sensitivity (79.2% vs 98.6% for observer 1; 84.7% vs 100% for observer 2) and specificity (80.7% vs 96.9%; 79.2% vs 95.4%) between the MDCT and noncontrast MRI (P < 0.05). We found similar diagnostic values between the noncontrast MRI and whole MRI (P = 0.479-1.000) for both observers. CONCLUSION: Noncontrast MRI could be a useful alternative to gadoxetic acid-enhanced MRI in the diagnosis of gallbladder carcinoma that presents as mild gallbladder wall thickening on MDCT.