Visual Assessment of the Intensity and Pattern of T1 Hyperintensity on MRI to Differentiate Hemorrhagic Renal Cysts From Renal Cell Carcinoma.

OBJECTIVE: The purpose of this study was to apply a visual assessment of the intensity and pattern of T1 hyperintensity at MRI to differentiate hemorrhagic renal cysts from renal cell carcinoma (RCC). MATERIALS AND METHODS: A total of 144 T1-hyperintense renal lesions (62 cysts, all showing no enhancement on subtracted contrast-enhanced images and either 2-year stability or unenhanced CT density > 70 HU, and 82 histologically confirmed RCCs) in 144 patients were included. Two radiologists independently characterized qualitative features of the T1 hyperintensity in each lesion on unenhanced T1-weighted images. An additional radiologist placed ROIs to measure lesions' T1 signal intensity normalized to that of the psoas muscle. Chi-square and unpaired t tests were performed to compare the pattern of T1 hyperintensity between groups. RESULTS: The T1 hyperintensity was considered marked in 62.9% of cysts and 17.1% of RCCs for reader 1 and in 46.8% of cysts and 8.5% of RCCs for reader 2 (p < 0.001). The T1 hyperintensity exhibited a diffusely homogeneous distribution in 88.7% of cysts and 7.3% of RCCs for reader 1 and in 72.6% of cysts and 4.9% of RCCs for reader 2 (p < 0.001). The combination of both diffusely homogeneous distribution and marked degree of T1 hyperintensity achieved sensitivities of 40.3-56.5%, specificities of 97.6-98.8%, and accuracies of 73.6-79.9% for the diagnosis of T1-hyperintense cysts. The two cases of RCC exhibiting this imaging pattern for at least one reader were both papillary RCCs. Normalized signal intensity was 2.39 ± 0.99 in T1-hyperintense cysts versus 2.12 ± 0.84 in T1-hyperintense RCCs (p = 0.088). CONCLUSION: Diffuse T1 hyperintensity, particularly when marked, strongly indicates a hemorrhagic cyst rather than an RCC. Deferral of follow-up imaging may be considered when this imaging appearance is encountered at unenhanced MRI.

Frequency and reasons for extra sequences in clinical abdominal MRI examinations.

PURPOSE: The purpose of the study was to identify the frequency and reasons for extra sequences in clinical liver MRI and MRCP examinations. METHODS: A total of 250 consecutive liver MRI and 250 consecutive MRCP examinations performed at a single institution were reviewed. Extra sequences performed in comparison with our standard institutional protocol were identified. Reasons for the extra sequences were identified. Overall trends were assessed. RESULTS: In significantly greater fractions of exams (p = 0.009-0.030), MRCP had ≥1 extra sequence (40.8% vs. 29.2%) and ≥2 extra sequences (16.0% vs. 5.6%) in comparison with the institutional protocol than did liver MRI. The average number of extra sequences was significantly higher (p = 0.004) for MRCP (0.73 ± 1.2) than liver MRI (0.44 ± 0.88). Reasons for extra sequences were as follows: sequence repeated for patient motion (33.8% for liver MRI; 31.9% for MRCP); sequence repeated for anatomic coverage (24.3% for liver MRI; 19.8% for MRCP); sequence added by the radiologist (15.3% for liver MRI; 33.0% for MRCP); sequence repeated for other reason (17.1% for liver MRI; 12.6% for MRCP); and sequence added by the technologist (5.4% for liver MRI; 2.7% for MRCP). The most commonly repeated sequence due to motion was the axial fat-saturated turbo spin-echo T2-weighted sequence for both liver MRI and MRCP (54.7% and 29.3% of sequences repeated due to motion, respectively). CONCLUSION: For liver MRI and MRCP exams, sequences were most often repeated due to motion artifact (most often occurring on TSE T2WI), and sequences were most often added by the radiologist. The findings may help guide sequence optimization, quality improvement initiatives, and standardization of operations, for improving efficiency in abdominal MRI workflow.