Foci of decreased signal on T2-weighted MR images in leiomyosarcomas of soft tissue: correlation between MR and histological findings

Renal cell carcinoma: t1 and t2 signal intensity characteristics of papillary and clear cell types correlated with pathology

OBJECTIVE

The objective of our study was to describe the T1 and T2 signal intensity characteristics of papillary renal cell carcinoma (RCC) and clear cell RCC with pathologic correlation.

MATERIALS AND METHODS

Of 539 RCCs, 49 tumors (21 papillary RCCs and 28 clear cell RCCs) in 45 patients were examined with MRI. Two radiologists retrospectively and independently assessed each tumor's T1 and T2 signal intensity qualitatively and quantitatively (i.e., the signal intensity [SI] ratio [tumor SI / renal cortex SI]). Of the 49 tumors, 37 (76%) were assessed for pathology features including tumor architecture and the presence of hemosiderin, ferritin, necrosis, and fibrosis. MRI findings and pathology features were correlated. Statistical methods included summary statistics and Wilcoxon's rank sum test for signal intensity, contingency tables for assessing reader agreement, concordance rate between the two readers with 95% CIs, and Fisher's exact test for independence, all stratified by RCC type.

RESULTS

Papillary RCCs and clear cell RCCs had a similar appearance and signal intensity ratio on T1-weighted images. On T2-weighted images, most papillary RCCs were hypointense (reader 1, 13/21; reader 2, 14/21), with an average mean signal intensity ratio for both readers of 0.67 +/- 0.2, and none was hyperintense, whereas most clear cell RCCs were hyperintense (reader 1, 21/28; reader 2, 17/28), with an average mean signal intensity ratio for both readers of 1.41 +/- 0.4 (p < 0.05). A tumor T2 signal intensity ratio of < or = 0.66 had a specificity of 100% and sensitivity of 54% for papillary RCC. Most T2 hypointense tumors exhibited predominant papillary architecture; most T2 hyperintense tumors had a predominant nested architecture (p < 0.05).

CONCLUSION

On T2-weighted images, most papillary RCCs are hypointense and clear cell RCCs, hyperintense. The T2 hypointense appearance of papillary RCCs correlated with a predominant papillary architecture at pathology.

[Gastric sarcoma]

Sarcoma of the stomach is a rare histological entity. These differentiated mesenchymal tumors do not differ clinically from other gastric cancers. Endoscopic ultrasonography is the preferred means of exploration because it determines the existence of a submucosal lesion and provides guidance in determining its type. Certainty of diagnosis requires pathologic and immunohistochemical examinations of the surgical specimen. Malignant gastric stromal tumors are the first differential diagnosis of sarcoma of the stomach. They can be better characterized by testing their expression of the c-kit protein. Histological confirmation of malignancy sometimes remains difficult. Locoregional invasion and distant metastases confirm malignancy. Treatment is essentially surgical. Prognosis depends on tumor size, extension, rupture and histological grade.