Co-existent Paget's Disease of the Bone, Prostate Carcinoma Skeletal Metastases and Fracture on Skeletal Scintigraphy-Lessons to be Learned.

UNLABELLED: Bone scintigraphy, despite being non-specific, is a very sensitive and simple investigation for patients with active Paget's disease of the bone. Skeletal metastases and Paget's disease may co-exist in the elderly patients as both conditions are commonly seen in this age group. Clinical and radiological correlation may help to improve the diagnostic specificity of a bone scintigram. We report a patient in whom concurrent Paget's disease and a rib fracture became evident only on repeat scintigraphy following successful treatment of prostate carcinoma skeletal metastases. CONFLICT OF INTEREST: None declared.

Oesophageal conduit - a cause of diffuse mediastinal uptake on thyroid scintigraphy.

UNLABELLED: 99mTc-pertechnetate scintigraphy plays an essential role in the management of a variety of thyroid and parathyroid disorders. The authors report an unusual case of mediastinal tracer distribution of 99mTc-pertechnetate and 99mTc-MIBI in relation to an oesophageal conduit following oesophago-gastrectomy and reconstructive surgery on thyroid scintigraphy. This is a rare but important cause of diffuse mediastinal uptake on thyroid scintigraphy. An awareness of abnormal anatomy as well as altered physiological tracer uptake would help to avoid any diagnostic pitfall. CONFLICT OF INTEREST: None declared.

Use of 111-Indium-labeled autologous eosinophils to establish the in vivo kinetics of human eosinophils in healthy subjects.

Eosinophils are the major cellular effectors of allergic inflammation and represent an important therapeutic target. Although the genesis and activation of eosinophils have been extensively explored, little is known about their intravascular kinetics or physiological fate. This study was designed to determine the intravascular life span of eosinophils, their partitioning between circulating and marginated pools, and sites of disposal in healthy persons. Using autologous, minimally manipulated 111-Indium-labeled leukocytes with blood sampling, we measured the eosinophil intravascular residence time as 25.2 hours (compared with 10.3 hours for neutrophils) and demonstrated a substantial marginated eosinophil pool. γ camera imaging studies using purified eosinophils demonstrated initial retention in the lungs, with early redistribution to the liver and spleen, and evidence of recirculation from a hepatic pool. This work provides the first in vivo measurements of eosinophil kinetics in healthy volunteers and shows that 111-Indium-labeled eosinophils can be used to monitor the fate of eosinophils noninvasively.

Detection of extensive melorheostosis on bone scintigram performed for suspected metastases.

Melorheostosis is a rare but benign disorder characterized by asymmetric osteosclerotic dysplasia. Radiographic appearances are characteristic and described as "melting wax flowing down a candle." This disorder may involve more than one bone contiguously across the joints following a sclerotomal distribution. It is often asymptomatic but occasionally presents with pain and contractures. The authors report accidental detection of bilateral upper and lower limb melorheostosis in an elderly woman with the history of breast cancer and recent onset of low back pain, which was referred for a bone scintigram for suspected metastases. The images showed bilateral femoral and tibial melorheostosis, which was subsequently confirmed on plain radiograph and by clinical follow-up.

Solitary phalangeal metastasis of renal cell carcinoma on bone scintigram.

Renal cell carcinoma is known to cause lytic metastasis at various sites including axial and appendicular skeleton. However, it is unusual to find an isolated metastasis of renal cell carcinoma in the distal extremity on bone scintigraphy. A 70-year-old woman with renal cell carcinoma was referred to the Nuclear Medicine Department for a bone scintigram to exclude metastasis. The whole-body planar images were unremarkable, but the local views of the hands demonstrated a solitary metastasis in the middle phalanx of the finger. This rare experience illustrates the need for including local views of extremities in a standard whole-body study.

What is the significance of solitary bony abnormalities on bone scintigrams of children with malignancy?

This investigation was undertaken to evaluate the significance of solitary bony abnormalities on bone scintigrams of children with known or suspected malignancy. A total of 215 bone scans were performed in 183 children in order to look for possible metastasis over a 10-year period. Forty-nine scans (22.8%) were found to have single lesions, of which 18 were due to uptake at the primary site and were excluded from further consideration. Of the remaining 31 lesions, 13 (41.9%) were confirmed as metastases, 17 lesions were proved to be benign, and 1 indeterminate. Solitary hot spots in children with known or suspected malignancy are common and therefore have to be taken seriously due to their higher malignant potential.

The role of bone scan in the diagnosis of carpal fracture in children.

A retrospective study was performed to evaluate the role of bone scan in the management of wrist trauma in children with equivocal radiographic findings. Thirty-one out of the 50 children showed no fracture. Six of them were treated for a median period of 9 days on clinical grounds; the others were discharged with reassurance. Four patients with evidence of soft tissue injury received no further treatment. Six of the 12 patients with a fracture on bone scan were treated with a cast for more than 4 weeks. None of the patients developed any complications. Bone scan is helpful when the diagnosis of a carpal fracture in children is equivocal.

Rhabdomyosarcoma with widespread bone marrow infiltration: beneficial management role of F-18 FDG PET.

Alveolar rhabdomyosarcoma (RMS) accounts for 20% to 30% of childhood RMS and is associated with a prognosis worse than embryonal RMS. Disseminated RMS can present with extensive bone marrow involvement. Assessing the extent of the tumor is critical, because therapy and prognosis depend on the degree to which the mass has spread beyond the primary site. The value of F-18 FDG PET in patients with RMS has been reported in some series but none specifically involving bone marrow. Children have a highly cellular hematopoietic bone marrow and differentiation of a highly cellular marrow from neoplastic infiltration may be difficult. Various other conditions associated with diffuse FDG uptake in the bone marrow include marrow hyperplasia resulting from hemolytic/iron-deficiency/blood-loss anemia, after chemotherapy with granulocyte/macrophage colony-stimulating factor and recombinant erythropoietin treatment, leukemia, non-Hodgkin lymphoma, and myelodysplasia. It is therefore important to consider the above differential diagnoses in mind when evaluating cases of unexpected marrow uptake in F-18 FDG PET studies. We report here a case of RMS with diffuse bone marrow involvement detected on F-18 FDG PET wherein FDG PET was useful in determining the true extent (primary and metastases) of RMS before definitive therapy and the valuable adjunct role it has with structural imaging in management.

AT2 receptor stimulation may halt progression of pheochromocytoma.

Two patients with pheochromocytoma are described in whom treatment with a high dose of an angiotensin receptor blocker was associated with cessation of tumor growth as assessed by serial CT scanning and plasma norepinephrine estimation. If the association with drug treatment is causal, the mechanism may be through stimulation of the AT2 receptor consequent upon the elevation of plasma angiotensin II levels induced by AT1 receptor blockade. Similar observations in further patients should lead to a placebo-controlled study in patients with malignant or familial pheochromocytoma, or other tumors found to express the AT2 receptor.

Can 16-detector multislice CT exclude skeletal lesions during tumour staging? Implications for the cancer patient.

Current imaging guidelines recommend that many cancer patients undergo soft-tissue staging by computed tomography (CT) whilst the bones are imaged by skeletal scintigraphy (bone scan). New CT technology has now made it feasible, for the first time, to perform a detailed whole-body skeletal CT. This advancement could save patients from having to undergo duplicate investigations. Forty-three patients with known malignancy were investigated for bone metastasis using skeletal scintigraphy and 16-detector multislice CT. Both studies were performed within six weeks of each other. Whole-body images were taken 4 h after injection of 500 Mbq (99m)Tc-MDP using a gamma camera. CT was performed on a 16-detector multislice CT machine from the vertex to the knee. The examinations were reported independently and discordant results were compared at follow-up. Statistical equivalence between the two techniques was tested using the Newcombe-Wilson method within the pre-specified equivalence limits of +/-20%. Scintigraphy detected bone metastases in 14/43 and CT in 13/43 patients. There were seven discordances; four cases were positive on scintigraphy, but negative on CT; three cases were positive on CT and negative on scintigraphy. There was equivalence between scintigraphy and CT in detecting bone metastases within +/-19% equivalence limits. Patients who have undergone full whole-body staging on 16-detector CT may not need additional skeletal scintigraphy. This should shorten the cancer patient's diagnostic pathway.

Extensive skeletal muscle uptake of 18F-FDG: relation to immunosuppressants?

A case of gross skeletal muscle uptake of 18F-FDG during PET is described. The clinical context of immunosuppression after heart and lung transplantation and the absence of any other known association make the former a likely etiologic factor.

Severe systemic reaction to (99m)Tc-methylene diphosphonate: a case report.

We report an unusual severe systemic reaction that occurred in a woman after a (99m)Tc-methylene diphosphonate bone scan and for which no alternative explanation could be found. The bone scintigram showed diffusely increased uptake in the liver and kidneys accompanied by reversible dysfunction of these organs and dermatologic manifestations. We speculate that an immune-mediated mechanism may have caused this unusual reaction.

Reduced hemithoracic uptake on 99mTc-MDP bone scintigraphy: an underrecognized sign of massive pleural effusion--a case report.

The uptake of (99m)Tc-methylene diphosphonate (MDP) in malignant pleural effusions and, rarely, in nonmalignant pleural effusions has been well documented in the literature. Although the exact mechanism of uptake in these conditions remains unclear, there have been attempts to use the bone scintigraphic features of pleural effusion to predict sensitivity and specificity for malignancy based on pleural fluid cytology. It has been suggested that activity in the chest increases with an increase in effusion volume. We report here, however, a case of malignant pleural effusion, that showed reduced hemithoracic activity in contrast to the expected increased activity. Our experience highlights the need for an open and inquisitive mind to avoid diagnostic pitfalls when confronted with a bone scintigram showing reduced uptake unilaterally or bilaterally in the chest.