Magnetic resonance (MR) imaging of the hip has been useful in the examination of patients for the presence of avascular necrosis (AVN). In the detection of AVN, MR imaging is more sensitive than computed tomography or nuclear scintigraphy. This study assessed the usefulness of MR imaging in the differentiation of AVN from other hip diseases. Twenty-two cases of non-AVN hip disease were matched with 23 biopsy-proved cases of AVN and ten normal controls. MR images were rated in a blinded manner by five experienced radiologists, and receiver operating characteristic (ROC) analysis was performed on the data. In the discrimination of AVN from other hip diseases or from normality, the A(z) value (the area under the ROC curve) was 98.6. With a specificity of 98%, MR imaging was 97% sensitive in the differentiation of AVN from normality, 85% sensitive in the differentiation of AVN from non-AVN disease, and 91% sensitive in the differentiation of AVN from both conditions. MR imaging may therefore help discriminate between AVN and other hip diseases.
In two pathologically documented cases of renal cell carcinoma, the appearance of the tumors at magnetic resonance (MR) imaging was markedly hypointense relative to normal renal parenchyma on both T1- and T2-weighted spin-echo images. Pathologic examination of both tumors revealed diffuse iron scattered throughout the tumors. The paramagnetic effect of the iron may account for this unusual hypointense appearance at spin-echo imaging, independent of pulse sequence.
The clinical and radiographic findings in 29 patients presenting with pulmonary sarcoidosis after the age of 50 years were reviewed. Fifty-nine percent (17 patients) had atypical findings at presentation. The atypical patterns at radiography included mediastinal adenopathy alone or in combination with unilateral hilar adenopathy (n = 8), solitary or multiple pulmonary masses (n = 3), and atelectasis (n = 3). Five patients had extrathoracic tumors at the time that the diagnosis of pulmonary sarcoidosis was made, which confused the diagnosis at radiography. An enhanced awareness of the atypical patterns of sarcoidosis in the older patient may facilitate the diagnostic process.
Knowledgeof the anatomy of the internal mammary vessels is important to avoid hemorrhagic complications when an anterior parasternal approach is used for percutaneous transthoracic procedures such as biopsy and empyema drainage. We examined 100 consecutive CT scans of the thorax to assess both the number of internal mammary vessels and their relation to the sternum.The mean distance from the sternum to the most medial vessel, the internal mammary vein, was 1.03 ± 0.25 cm on the right side and 0.98 ± 0.23 cm on the left side. The mean distance from the sternum to the most lateral vessel, the internal mammary artery, was 1.57 ± 0.30 cm on the right and 1.47 ± 0.30 cm on the left. Three internal mammary vessels were present in 20% of cases on the right side and in 18% on the left side. In nine patients, the internal mammary artery was greater than 2.0 cm from the lateral border of the sternum.We recommend an approach that is greater than 2.5 cm from the sternal border when performing parasternal percutaneous transthoracic procedures in order to avoid hemorrhagic complications from injury to the internal mammary vessels. A "safe" window does exist medially between the sternal border and the internal mammary vein but should be used only in procedures performed under CT guidance.
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