Bone Scan and SPECT/CT Findings in Marble Bone Disease.

Abstract

Marble bone disease or osteopetrosis (OS), is a rare inborn disorder characterized by the failure of osteoclasts to resorb bone [1]. Overall incidence of the disease is estimated to be 1 case in 100,000-500,000 population [2]. Whereas the radiographic features of the disease are well known, information on bone scan imaging is sparse in the literature. We present technetium-99m methylene diphosphonate (99mTc MDP) bone scan features of osteopetrosis,along with single photon emission computed tomography–computed tomography(SPECT/CT) correlation in a young male (Fig. 1). Fig. 1 A 23-year-old man underwent a 99mTc MDP bone scan for the evaluation of sclerotic lesions in the pelvis found on a radiograph obtained for his hip pain. On planar scan (a, b), intense tracer uptake was noted in the entire skeleton, notably in the proximal ... On conventional imaging, generalized sclerosis, more commonly in metaphyseal regions is seen in bones. Various patterns described on bone scan include diffuse increased uptake that may also be a “Superscan” and non-uniform uptake with foci of hyperemia [3–5]. Use of SPECT/CT in OS has not been described in literature previously. In our case, SPECT/CT was performed to rule out fracture of left femur or pelvic bone as a cause of patient’s symptoms. It is known that pelvic X-ray has limited value for detecting pelvic fractures compared with CT scanning and hence we performed SPECT/CT even when the radiographs were available [6]. In such a case, planar imaging alone will miss the uptake secondary to fracture as it will be masked by metaphyseal areas of intense tracer uptake. Additional advantage of SPECT/CT in such cases is that it can confirm that the areas of abnormal tracer uptake are limited to metaphyseal regions and hence can clinch the diagnosis of OS. In general, radiographic findings are considered sufficient for diagnosis of OS and biopsy is reserved only in pre-bone marrow transplant work-up, in cases where diagnosis is unclear or for genetic diagnosis [7]. SPECT or SPECT/CT can be used as a problem solving tool when conventional imaging findings are inconclusive or pathological fracture is suspected. Our case illustrates bone scan and SPECT/CT findings of this rare disorder. Though rare, this diagnosis should be kept in mind when similar uptake pattern and CT characteristics are encountered in practice.