Causes of photopenic defects in the lower sternum on bone scintigraphy and correlation with multidetector CT

To determine the cause of this photopenia in the lower sternum on bone scintigraphy and its correlation with sternal foramen on multidetector computed tomography (MDCT).

Between January and December 2008, we studied 1053 patients who underwent bone scintigraphy and CT scanning that included the chest. Bone scintigraphy showed photopenic areas in the lower sternum in 58 of these 1053 patients. The study population consisted of 19 men and 37 women, aged from 15 to 87 years (mean: 60.4 years).

Of the 58 patients with photopenic areas in the lower sternum, 25 (43%) showed a sternal foramen by MDCT, whereas 33 patients (57%) showed no sternal foramen. However, of the total study population of 1053 patients, MDCT showed sternal foramen in 33 patients (3.1%). In 7 of the 33 patients with sternal foramen by MDCT, bone scintigraphy showed no photopenic areas. On the basis of CT morphometry of the sternum, the possible causes of photopenia in the lower sternum in patients without sternal foramen are as follows: thin middle portion of sternum bone marrow, a focal defect or notch in the posterior sternal cortex, high accumulation of peripheral lesions, and bone metastasis.

This study revealed that not all patients showing photopenic areas in the lower sternum have sternal foramen and not all patients with sternal foramen show photopenic areas by bone scintigraphy. It is important to exclude metastasis when photopenic areas are detected, and inform the clinician to avoid the serious complication of cardiac tamponade.