Chemical shift magnetic resonance imaging for distinguishing minimal-fat renal angiomyolipoma from renal cell carcinoma: a meta-analysis.

OBJECTIVES: To determine the performance of chemical shift signal intensity index (CS-SII) values for distinguishing minimal-fat renal angiomyolipoma (mfAML) from renal cell carcinoma (RCC) and to assess RCC subtype characterisation. METHODS: We identified eligible studies on CS magnetic resonance imaging (CS-MRI) of focal renal lesions via PubMed, Embase, and the Cochrane Library. CS-SII values were extracted by lesion type and evaluated using linear mixed model-based meta-regression. RCC subtypes were analysed. Two-sided p value <0.05 indicated statistical significance. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. RESULTS: Eleven articles involving 850 patients were included. Minimal-fat AML had significantly higher CS-SII value than RCC (p < 0.05); there were no significant differences between mfAML and clear cell RCC (cc-RCC) (p = 0.112). Clear cell RCC had a significantly higher CS-SII value than papillary RCC (p-RCC) (p < 0.001) and chromophobe RCC (ch-RCC) (p = 0.045). The methodological quality was relatively high, and Begg's test data points indicated no obvious publication bias. CONCLUSIONS: The CS-SII value for differentiating mfAML from cc-RCC remains unproven, but is a promising method for differentiating cc-RCC from p-RCC and ch-RCC. KEY POINTS: • RCC CS-SII values are significantly lower than those of mfAML overall. • CS-SII values cannot aid differentiation between mfAML and cc-RCC. • CS-SII values might help characterise RCC subtypes.

Relation between brown adipose tissue and measures of obesity and metabolic dysfunction in patients with cardiovascular disease.

PURPOSE: To evaluate whether brown adipose tissue (BAT) is present in middle-aged patients with cardiovascular comorbidities and to quantify how BAT presence associates with obesity and metabolic dysfunction. MATERIALS AND METHODS: Supraclavicular and subcutaneous adipose tissue fat-signal-fraction (FF) was determined with 1.5T water-fat magnetic resonance imaging (MRI) in 50 patients with coronary artery disease, cerebrovascular disease, or peripheral artery disease. The association between BAT presence, as measured by a higher FF difference between supraclavicular and subcutaneous adipose tissue, and obesity and metabolic dysfunction was quantified using multivariable linear regression. RESULTS: Supraclavicular adipose tissue displays a lower FF of 82.6% (interquartile range [IQR] 78.8-84.3) compared to 90.2% (IQR 87.3-91.9) in subcutaneous white adipose tissue (WAT, P < 0.0001). BAT presence was associated with less obesity and metabolic dysfunction. For example, 1 SD lower waist circumference (11.7 cm), 1 SD lower triglycerides (1.0 mmol/L), and absence of metabolic syndrome and type 2 diabetes were associated with 1.1% (95% confidence interval [CI] 0.1; 2.0), 1.1% (95% CI 0.1; 2.0), 2.1% (95% CI 0.1; 4.1), and 4.1% (95% CI 0.1; 7.1) higher FF difference between supraclavicular adipose tissue and subcutaneous WAT, respectively. CONCLUSION: Supraclavicular adipose tissue has BAT characteristics in adult patients with clinical manifest cardiovascular disease and BAT presence is associated with less obesity and a more favorable metabolic profile. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:497-504.

Characteristic findings of primary perirenal angiosarcoma on chemical shift subtraction magnetic resonance imaging (CSS-MRI): A case report.

A 70-year-old man with supraglottic carcinoma underwent computed tomography (CT) for staging purposes. A tumor measuring approximately 7 × 10 cm was found incidentally in the left perirenal space. The tumor showed homogeneous high signal intensity on chemical shift subtraction magnetic resonance imaging (CSS-MRI) suggesting the presence of minimal amounts of fat. Five months later, the tumor had grown to approximately 10 × 12 cm with indistinct margins. CSS-MRI showed high signal intensity in the tumor periphery only. The tumor was resected and the pathological diagnosis was angiosarcoma. Angiosarcomas are malignant endothelial vascular neoplasms that are highly invasive to their surroundings. Here we report a case of primary perirenal angiosarcoma that was difficult to differentiate from a dedifferentiated liposarcoma. On CSS-MRI, high signal intensity within a tumor may be a characteristic feature of primary perirenal angiosarcoma.

The added value of chemical shift MRI in the preoperative diagnosis of thymolipoma.

Thymolipoma is a rare tumor of the thymus. Classic radiologic findings of thymolipoma include fatty masses of the anterior mediastinum in conjunction with the thymus. Differential diagnosis with other more aggressive entities like liposarcoma and teratoma can be challenging. We report a case where chemical shift magnetic resonance imaging helped in the differential diagnosis.

Computed tomography and magnetic resonance imaging features of lipid-rich neuroendocrine tumors of the pancreas.

AIM: To clarify the computed tomography (CT) and magnetic resonance imaging (MRI) characteristics of lipid-rich pancreatic neuroendocrine tumors (PanNETs). METHODS: Enhanced CT and MRI performed before pancreatectomy in 29 patients with 34 histologically-confirmed PanNETs was retrospectively reviewed. Tumor attenuation on CT and signal intensities on conventional (T1- and T2-weighted) and chemical shift MRI were qualitatively analyzed and compared alongside adipose differentiation-related protein (ADRP) immunostaining (ADRP-positive: lipid-rich; ADRP-negative: non-lipid-rich) results using Fisher's exact test or the Mann-Whitney U test. Signal intensity index on chemical shift MRI was quantitatively assessed. RESULTS: There were 15 lipid-rich PanNETs (44.1%) in 12 patients (41.4%). Tumor attenuation during the early, portal venous, and delayed phases of enhanced CT (P = 0.888, 0.443, and 0.359, respectively) and signal intensities on conventional MRI (P = 0.698 and 0.798, respectively) were not significantly different between lipid-rich and non-lipid-rich PanNETs. Four of the 15 lipid-rich PanNETs exhibited high signal intensity on subtraction chemical shift MRI, and the association of high signal intensity on subtraction imaging with lipid-rich PanNETs was significant (4 of 15 lipid-rich PanNETs, 26.73%, vs 0 of 19 non-lipid-rich PanNETs, 0%, P = 0.029). Lipid-rich PanNETs showed a significantly higher signal intensity index than non-lipid-rich PanNETs (0.6% ± 14.1% vs -10.4% ± 14.4%, P = 0.004). Eight of 15 lipid-rich PanNETs, vs 0 of 19 non-lipid-rich PanNETs, had positive signal intensity index values in concordance with lipid contents. CONCLUSION: CT contrast enhancement and conventional MR signal intensities are similar in lipid-rich and non-lipid-rich PanNETs. Chemical shift MRI can demonstrate cytoplasmic lipids in PanNETs.