Superscan caused by renal osteodystrophy: Observed on 18F FDG PET/CT scan

Metabolic Superscan on 18 F-FDG PET/CT in a Patient With Secondary Hyperparathyroidism

ABSTRACT

Superscan on PET/CT has been reported in the literature and mainly involved metastatic diseases. We report an uncommon case of a metabolic superscan on 18 F-FDG PET/CT in a 56-year-old man with end-stage renal disease on hemodialysis who presented with secondary hyperparathyroidism. Parathyroid scintigraphy showed 2 lesions posteroinferior to both thyroid lobes, suggestive of parathyroid adenoma/hyperplasia. FDG PET/CT performed to assess for pulmonary nodules revealed diffuse FDG hypermetabolism involving the visualized skull, mandible, spine, sternum, ribs, and appendicular skeleton without corresponding CT lesion with no urinary radiotracer excretion, consistent with metabolic superscan secondary to renal osteodystrophy.

Nuclear medicine imaging findings in end-stage renal disease and renal transplant complications

The aim of this review is to discuss end-stage renal disease (ESRD) and renal transplant complications and present the nuclear medicine imaging findings. The conditions discussed are renal osteodystrophy, metastatic calcification, and renal transplant complications, such as vascular occlusion and acute tubular necrosis. A total of eight nuclear medicine imaging scintigraphy primarily of bone and renal scintigraphy were selected and the imaging features of the complications are discussed. This article highlights the role of nuclear medicine imaging in diagnosis, quantitative and qualitative assessment of renal function, and monitoring of complications associated with ESRD and renal transplant.

FDG-PET/CT Variants and Pitfalls in Haematological Malignancies

Hematologic malignancies represent a vast group of hematopoietic and lymphoid cancers that typically involve the blood, the bone marrow, and the lymphatic organs. Due to extensive research and well defined and standardized response criteria, the role of [¹⁸F]FDG-PET/CT is well defined in these malignancies. Never the less, the reliability of visual and quantitative interpretation of PET/CT may be impaired by several factors including inconsistent scanning protocols and image reconstruction methods. Furthermore, the uptake of [¹⁸F]FDG not only reflects tissue glucose consumption by malignant lesions, but also in other situations such as in inflammatory lesions, local and systemic infections, benign tumors, reactive thymic hyperplasia, histiocytic infiltration, among others; or following granulocyte colony stimulating factors therapy, radiation therapy, chemotherapy or surgical interventions, all of which are a potential source of false-positive or negative interpretations. Therefore it is of paramount importance for the Nuclear Medicine Physician to be familiar with, not only the normal distribution of [¹⁸F]FDG in the body, but also with the most frequent findings that may hamper a correct interpretation of the scan, which could ultimately alter the patients management. In this review, we describe these myriad of situations so the interpreting physician can be familiar with them, providing tools for their correct identification and interpretation when possible.

The Non-invasive Diagnosis of Bone Disorders in CKD

Abnormal bone metabolism is an integral part of the chronic kidney disease-mineral bone disorder (CKD-MBD). For several reasons, the difficult bone compartment was neglected for some time, but there has been renewed interest as a result of the conception of bone as a new endocrine organ, the increasing recognition of the cross-talk between bone and vessels, and, especially, the very high risk of osteoporotic fractures (and associated mortality) demonstrated in patients with CKD. Therefore, it has been acknowledged in different guidelines that action is needed in respect of fracture risk assessment and the diagnosis and treatment of osteoporosis in the context of CKD and CKD-MBD, even beyond renal osteodystrophy. These updated guidelines clearly underline the need to improve a non-invasive approach to these bone disorders in order to guide treatment decisions aimed at not only controlling CKD-MBD but also decreasing the risk of fracture. In this report, we review the current role of the most often clinically used or promising biochemical circulating biomarkers such as parathyroid hormone, alkaline phosphatases, and other biochemical markers of bone activity as alternatives to some aspects of bone histomorphometry. We also mention the potential role of classic and new imaging techniques for CKD patients. Information on many aspects is still scarce and heterogeneous, but many of us consider that it is indeed time for action, recognizing our definitely limited ability to base certain treatment decisions only on our current non-comprehensive knowledge.

18F-FDG PET/CT Findings in a Patient With Neutrophilic Leukemoid Reaction Associated With Multiple Myeloma

F-FDG PET/CT was performed on a 48-year-old woman with leukocytosis (white blood cell count 57.10 × 10/L, 84.0% neutrophils) and monoclonal gammopathy to investigate the possibility of reactive neutrophilia secondary to plasmacytoma. On the background of skeletal "superscan," the maximum intensity projection image of PET demonstrated the highest metabolic region in the left sacrum, which was confirmed as an osteolytic lesion by CT. Biopsy of the sacral lesion revealed a plasma cell myeloma, indicating the diagnosis of neutrophilic leukemoid reaction associated with multiple myeloma. The white blood cell counts dramatically dropped to the normal level after 1 cycle of chemotherapy for multiple myeloma.

Diffuse Skeletal Uptake on 18F-Fluoro-2-Deoxy-d-glucose Positron Emission Tomography/Computed Tomography Scan in a Patient with Acute Lymphoblastic Leukemia: A Typical Superscan Pattern Resembling NaF Positron Emission Tomography Scan

A 65-year-old patient with acute lymphoblastic leukemia presented for an 18fluoro-2-deoxy-d-glucose positron emission tomography computed tomography (18FDG PET) after several courses of chemotherapy for metastatic evaluation. Unexpectedly, on 18FDG PET scan, no discernible uptake was observed in the visceral organs, but instead, the skeleton/bone marrow showed homogenously intense metabolic activity. The distribution of 18FDG observed on the scan was remarkably similar to that on the NaF PET scan, indicating a superscan appearance.

Tertiary Hyperparathyroidism With Renal Osteodystrophy on 18F-Fluorocholine PET/CT

A 27-year-old man, with a history of chronic renal failure due to obstructive uropathy, treated with hemodialysis and awaiting kidney transplantation, presented with tertiary hyperparathyroidism. Despite regulation of phosphate and calcium and treatment with cinacalcet, the serum parathyroid hormone levels remained elevated. The patient was referred for parathyroidectomy, and a F-fluorocholine PET/CT was acquired for preoperative planning. Besides visualization of the hyperfunctioning parathyroid glands, the scan also showed a typical picture of renal osteodystrophy, a finding on F-fluorocholine PET/CT that has not been reported before.

Renal osteodystrophy presenting as a metabolic superscan on F-18 FDG PET/CT: A case report

RATIONALE

F-18 Fluoro Deoxyglucose positron emission tomography and computed tomography (F-18 FDG PET/CT) is a useful modality in the evaluation of patients with malignancies. Increased incidence of lympho-proliferative disorders has been reported in individuals with long-standing end-stage renal disorders treated with renal replacement therapy.

PATIENT CONCERNS

A 30-year-old male on peritoneal dialysis on account of end-stage renal disease. He had acute rejection of an earlier transplanted renal allograft. He was referred for an F-18 FDG PET/CT based on a clinical suspicion of lymphoma on account of bilateral inguinal lymphadenopathy associated with bilateral pedal swelling.

DIAGNOSIS

Renal osteodystrophy was diagnosed based on diffusely intense F-18 FDG uptake in the axial skeleton, focal uptake in the costochondrial junctions and linear cortical uptake in the appendicular skeleton. No findings suggestive of lymphoma was seen.

INTERVENTIONS

A diagnosis of renal osteodystrophy with no evidence of a lymphoma prevented futile biopsy of inguinal lymphadenopathy. Patient continued with peritoneal dialysis with no further intervention OUTCOMES:: Regular follow-up of patient to monitor calcium, phosphate and parathyroid hormone levels. Treatment will be indicated when laboratory results as well as clinical signs and symptoms are suggestive.

LESSON

Metabolic bone disorder such as is seen in renal osteodystrophy should be considered in the differential diagnoses in patients with diffusely increased bone uptake on F-18 FDG PET/CT scan.