Diffuse pulmonary uptake of 99mTc bone-imaging agents: Case report and survey

Abstract

Over the past 5 years, we have encountered 6 cases of diffuse pulmonary uptake of 99m-Tc bone-scanning agents (incidence, 0.04%). To assess the significance of this phenomenon, we reviewed all of the cases reported since 1974 (Including our series, a total of 32 cases). Three groups can be discerned, the first consisting of 24 patients without radiological calcifications in the lungs and with hypercalcemia of different origins (mostly hyperparathyroidism). Of the eight autopsies performed in this group, seven revealed extensive calcifications in alveolar walls and lung vessels; the other autopsy showed no calcification at all and only bronchopneumonic lesions. The second group consists of 6 patients in chronic dialysis. The last group consists of 2 patients having diffuse pulmonary alveolar microlithiasis with extensive radiologic calcifications. The mechanism of lung uptake of 99m-Tc bone-imaging agents is probably the same as that of bone uptake (chemisorption on hydroxyapatite crystals), although other uptake mechanisms have also been discussed. Bone scintigraphy can be useful in the detection of early pulmonary calcifications, which have been associated with impaired pulmonary function and, due to their size, are generally not detected by X-ray.

FDG-PET/CT finding of high uptake in pulmonary alveolar microlithiasis

“…Multiple pulmonary nodular calcifi cations on chest X-ray and CT are a pathognomonic fi nding of PAM, and diffuse and intense tracer uptake in both lungs on bone scintigraphy is widely known [2][3][4]. To the best of our knowledge, there have been no reports on FDG uptake by the lung in cases of PAM.…”

“…Although computed tomography (CT) and bone scintigraphic fi ndings of PAM have been reported earlier, the uptakes of 18 F-fl uorodeoxyglucose (FDG) in FDG-positron emission tomography (PET)/CT in lung are not yet known [2][3][4]. FDG-PET has come to be recognized as a useful tumor imaging technique on the basis of the elevated glucose metabolism in tumor cells.…”

Diffuse Pulmonary Uptake of Tc-99m Methylene Diphosphonate in a Patient with Non-tuberculosis Mycobacterial Infection

“…Even then, the calcifications seen radiographically did not correspond to the scintigraphic patterns. In contrast, only two patients with no biochemical abnormalities had extensive radiologic calcifications and were diagnosed with diffuse alveolar microlithiasis [9].…”

Metastatic Pulmonary Calcification in Sarcoidosis

“…Although polar (cationic strontium, an ionic fluoride) and nonpolar (99mTc-Iabelled diphosphonates and pyrophos phates) bone seeking radioisotopes have been used in the past [11], currently only the latter agents are being used to image metastatic pulmonary calcification [12]. The mechanism by which these radioiso topes localize in extra-osseous sites of cal cification is not well understood, even so the use of these agents remains a noninvasive, relatively specific and fairly sensitive way to detect metastatic pulmonary calci fication.…”