Soft tissue uptake on ^99mTc methylene diphosphonate bone scan imaging: Pictorial review

Abstract

99mTechnetium methylene diphosphonate (MDP) bone isotope may accumulate in many extra-osseous sites due to a variety of both benign and malignant conditions. This finding on a bone scan can be crucial to the diagnosis and may not be apparent in other imaging or the clinical evaluation of the patient. We present a pictorial review sampling some of the many causes of extra-osseous 99mTc MDP accumulation.

Early disappearance of calcification in posterior paraspinal muscles in a patient with rhabdomyolysis associated with neuroleptic malignant syndrome

“…Previous reports showed that sometimes tracer uptake during bone scintigraphy precedes detection of ectopic calcification by other modalities, such as CT or plain radiography. 11 In our case the increased HMDP uptake preceded the detection of ectopic calcification by CT in the affected muscles.…”

Extraosseous Findings on Bone Scintigraphy Using Fusion SPECT/CT and Correlative Imaging

“…It is imperative that the interpreting physician has an understanding of the wide range of causes of uptake in extraosseous structures, because many of these findings are artifactual or related to quality-control issues and could be misinterpreted as disease [6]. The detection, proper analysis, and reporting of these extraosseous findings are important because they may alert the referring physician to previously undetected disease processes [6,7].…”

“…The range of underlying entities can generally be categorized into several basic classes according to mechanism: vascular entities (altered regional blood flow, blood volume, capillary permeability, and com- partmental sequestration), neoplasms, extraosseous calcifications (dystrophic or tissue injury), and metabolic entities (metabolic bone disease or malignant calcification) [3][4][5][6][7]. It should be noted that these mechanisms are often multifactorial [6].…”

“…In routine clinical practice, quality-control issues, artifacts, or spurious activity, including radiotracer preparation, prior radionuclide diagnostic imaging, and contamination, are the most commonly encountered cause of extraosseous radioactivity and should be actively sought out and excluded [3,4,6,7]. Urinary contamination on the skin surface is suspected when intense radiopharmaceutical activity is noted in the superficial soft tissue of the pelvis or lower extremities.…”

Liver metastasis of lung cancer detected with similar uptake pattern on bone scintigraphy and fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography: What's the pathophysiologic mechanism?

“…[1234] Multiple factors can affect extra-osseous MDP uptake: (1) Technical factors, (2) primary malign and metastatic lesions, (3) soft tissue, (4) amyloidosis, (5) infraction, (6) hypercalcemia, (7) inflammation, (8) chemotherapy and (9) radiotherapy. [5678] MDP accumulates, especially within calcified hepatic metastasis. However, in the present case, liver metastasis not showed calcification in CT examination.…”