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SPECT bone scintigraphy has been shown useful for detecting avascular necrosis (AVN) of the femoral heads. Because the femoral necks project in a 15-20 degree posterior angulation from the coronal plane, the femoral head is partially superimposed upon the acetabulum in standard coronal SPECT images. To avoid this problem, the authors now perform oblique angle reorientation of all hip SPECT studies. This new technique, which allows display of the hip in a more anatomic fashion and better definition of hip abnormalities, is described. No new data acquisition is needed, and only a small amount of extra time is required for reconstruction.

Although [99mTc] diethylenetriaminepentaacetic acid (DTPA) is currently the most widely used radioaerosol, rapid alveolar clearance limits its usefulness for single photon emission computed tomography (SPECT) ventilation lung imaging. Previous research has shown that [99mTc]phosphate compounds have high alveolar deposition and slow clearance and thus provide suitable aerosols for pulmonary ventilation studies. We have compared the pulmonary retention and blood levels of [99mTc]pyrophosphate (PYP) and [99mTc]DTPA in eight normal nonsmoking male volunteers. These two radioaerosols have comparable pulmonary deposition. Technetium-99m PYP, however, has a much slower pulmonary clearance which allows sufficient time (20 or more minutes) for SPECT data acquisition using a single-headed rotating gamma camera. While the radiation absorbed dose to the lungs for [99mTc]PYP (0.31 rad/mCi) is greater than for [99mTc]DTPA (0.11 rad/mCi), it is at a clinically acceptable and safe level.