Spinal phosphaturic mesenchymal tumors: a rare etiology causing tumor-induced osteomalacia-a review of experience at a UK tertiary referral center and literature review.

PURPOSE: This article aims to provide a comprehensive review of the management challenges associated with Spinal Phosphaturic Mesenchymal tumors (PMTs) and evaluates the surgical management outcomes for this rare entity linked to Tumor-induced osteolysis. The primary objective of this study is to enhance the familiarity of treating physicians with the clinical features, diagnosis, and treatment options for Spinal PMTs. METHODS: A retrospective analysis was conducted, reviewing electronic medical records of patients diagnosed with spinal PMTs at our hospital between January 2019 and December 2022. The data collected included demographic information, clinical presentation, radiological findings, surgical details, and follow-up outcomes. RESULTS: A total of three cases of Spinal PMTs causing Tumor-induced osteomalacia were identified. The diagnosis of Spinal PMTs presented challenges, with incidental detection often occurring during routine imaging. Surgical management was undertaken, resulting in successful symptom resolution and normalization of phosphate levels. The application of 68 Ga-DOTA-TATE PET/CT scans facilitated tumor localization, aiding in surgical planning. Spinal PMTs demonstrated a favorable response to surgical intervention. CONCLUSION: Spinal PMTs play a significant role in Tumor-induced osteolysis, warranting timely and accurate diagnosis. Although diagnosing Spinal PMTs presents challenges, surgical management has proven to yield favorable outcomes, effectively alleviating symptoms and restoring phosphate levels. A multidisciplinary approach and continued vigilance are essential in ensuring early diagnosis, effective treatment, and long-term monitoring for patients affected by spinal PMTs.

Somatostatin Receptor Targeted PET-CT and Its Role in the Management and Theranostics of Gastroenteropancreatic Neuroendocrine Neoplasms.

Somatostatin receptor (SSTR) agonist-based Positron Emission Tomography-Computed Tomography (PET-CT) imaging is nowadays the mainstay for the assessment and diagnostic imaging of neuroendocrine neoplasms (NEN), especially in well-differentiated neuroendocrine tumors (NET) (World Health Organization (WHO) grade I and II). Major clinical indications for SSTR imaging are primary staging and metastatic workup, especially (a) before surgery, (b) detection of unknown primary in metastatic NET, (c) patient selection for theranostics and appropriate therapy, especially peptide receptor radionuclide therapy (PRRT), while less major indications include treatment response evaluation on and disease prognostication. Dual tracer PET-CT imaging using SSTR targeted PET tracers, viz. [68Ga]Ga-DOTA-Tyr3-Octreotate (DOTA-TATE) and [68Ga]Ga-DOTA-NaI3-Octreotide (DOTA-NOC), and fluorodeoxyglucose (FDG), have recently gained widespread acceptance for better assessment of whole-body tumor biology compared to single-site histopathology, in terms of being non-invasive and the ability to assess inter- and intra-tumoral heterogeneity on a global scale. FDG uptake has been identified as independent adverse risk factor in various studies. Recently, somatostatin receptor antagonists have been shown to be more sensitive and specific in detecting the disease. The aim of this review article is to summarize the clinical importance of SSTR-based imaging in the clinical management of neuroendocrine and related tumors.

Cost-Effectiveness Analysis of 68Ga DOTA-TATE PET/CT, 111In-Pentetreotide SPECT/CT and CT for Diagnostic Workup of Neuroendocrine Tumors.

Neuroendocrine tumors (NETs) are relatively rare neoplasms arising from the hormone-producing neuroendocrine system that can occur in various organs such as pancreas, small bowel, stomach and lung. As the majority of these tumors express somatostatin receptors (SSR) on their cell membrane, utilization of SSR analogs in nuclear medicine is a promising, but relatively costly approach for detection and localization. The aim of this study was to analyze the cost-effectiveness of 68Ga-DOTA-TATE PET/CT (Gallium-68 DOTA-TATE Positron emission tomography/computed tomography) compared to 111In-pentetreotide SPECT/CT (Indium-111 pentetreotide Single Photon emission computed tomography/computed tomography) and to CT (computed tomography) alone in detection of NETs. A decision model on the basis of Markov simulations evaluated lifetime costs and quality-adjusted life years (QALYs) related to either a CT, SPECT/CT or PET/CT. Model input parameters were obtained from publicized research projects. The analysis is grounded on the US healthcare system. Deterministic sensitivity analysis of diagnostic parameters and probabilistic sensitivity analysis predicated on a Monte Carlo simulation with 30,000 reiterations was executed. The willingness-to-pay (WTP) was determined to be $ 100,000/QALY. In the base-case investigation, PET/CT ended up with total costs of $88,003.07 with an efficacy of 4.179, whereas CT ended up with total costs of $88,894.71 with an efficacy of 4.165. SPECT/CT ended up with total costs of $89,973.34 with an efficacy of 4.158. Therefore, the strategies CT and SPECT/CT were dominated by PET/CT in the base-case scenario. In the sensitivity analyses, PET/CT remained a cost-effective strategy. This result was due to reduced therapy costs of timely detection. The additional costs of 68Ga-DOTA-TATE PET/CT when compared to CT alone are justified in the light of potential savings in therapy costs and better outcomes.

Diagnostic value of 68Ga-DOTA-TATE PET/CT imaging for tumor- induced osteomalacia.

BACKGROUND: Tumor-induced osteomalacia (TIO) is often misdiagnosed as hypophosphatemia that is not valued. The aim of this study was to analyze the diagnostic value of 68Ga-DOTA-TATE PET/CT imaging for TIO. METHODS: Clinical data was retrospectively collected for 56 patients with suspected TIO at the Affiliated Hospital of Southwest Medical University between January 2016 and December 2019, where patients were examined by 68Ga-DOTA-TATE PET/CT and 99mTc-HYNIC-TOC SPECT. Based on the results of the patient's surgery, the diagnostic efficacy of the two imaging techniques on TIO were analyzed. RESULTS: Of the 56 patients, 41 were diagnosed with TIO, with phosphorus levels ranging from 0.25 to 0.75 mmol/L. The remaining 15 patients were non-TIO. Results of 99mTc-HYNIC-TOC SPECT showed 33 cases were positive, with a diagnostic sensitivity, specificity, and accuracy of 58.54%, 86.67%, and 66.07%, respectively. Results of 68Ga-DOTA-TATE PET/CT imaging showed 46 cases were positive, with a diagnostic sensitivity, specificity, and accuracy of 95.13%, 60.00%, 71.43%, respectively. The average tumor size with 68Ga-DOTA-TATE PET/CT imaging was 2.58±1.71 cm. The lesions of 41 patients involved bone and soft tissue, while 18 patients showed osteolytic bone destruction. Distribution was mainly under the skin, followed by intermuscular space, and cortex of bone. Compared with muscle density, the lesions showed uniformly or slightly lower density nodules. Using 99mTc-HYNIC-TOC SPECT, the planar imaging of 30 patients showed that radioactive uptake increased at the early stage, and it can be accurately positioned on the SPECT imaging. CONCLUSIONS: The 68Ga-DOTA-TATE PET/CT imaging demonstrated high accuracy in the diagnosis of TIO and detected small lesions, which could provide more comprehensive information for clinicians, and provide a reference value for the treatment and prognosis of patients.

Guidelines on nuclear medicine imaging in neuroblastoma.

Nuclear medicine has a central role in the diagnosis, staging, response assessment and long-term follow-up of neuroblastoma, the most common solid extracranial tumour in children. These EANM guidelines include updated information on 123I-mIBG, the most common study in nuclear medicine for the evaluation of neuroblastoma, and on PET/CT imaging with 18F-FDG, 18F-DOPA and 68Ga-DOTA peptides. These PET/CT studies are increasingly employed in clinical practice. Indications, advantages and limitations are presented along with recommendations on study protocols, interpretation of findings and reporting results.

68Ga DOTA-TATE PET/CT allows tumor localization in patients with tumor-induced osteomalacia but negative 111In-octreotide SPECT/CT.

Tumor-induced osteomalacia (TIO) is a paraneoplastic syndrome characterized by renal phosphate wasting, hypophosphatemia and low calcitriol levels as well as clinical symptoms like diffuse bone and muscle pain, fatigue fractures or increased fracture risk. Conventional imaging methods, however, often fail to detect the small tumors. Lately, tumor localization clearly improved by somatostatin-receptor (SSTR) imaging, such as octreotide scintigraphy or octreotide SPECT/CT. However, recent studies revealed that still a large number of tumors remained undetected by octreotide imaging. Hence, studies focused on different SSTR imaging methods such as 68Ga DOTA-NOC, 68Ga DOTA-TOC and 68Ga DOTA-TATE PET/CT with promising first results. Studies comparing different SSTR imaging methods for tumor localization in TIO are rare and thus little is known about diagnostic alternatives once a particular method failed to detect a tumor in patients with TIO. Here, we report the data of 5 consecutive patients suffering from TIO, who underwent both 111Indium-octreotide scintigraphy (111In-OCT) SPECT/CT as well as 68Ga DOTA-TATE PET/CT for tumor detection. While 111In-OCT SPECT/CT allowed tumor detection in only 1 of 5 patients, 68Ga DOTA-TATE PET/CT was able to localize the tumor in all patients. Afterwards, anatomical imaging of the region of interest was performed with CT and MRI. Thus, successful surgical resection of the tumor was achieved in all patients. Serum phosphate levels returned to normal and all patients reported relief of symptoms within weeks. Moreover, an iliac crest biopsy was obtained from every patient and revealed marked osteomalacia in all cases. Follow-up DXA revealed an increase in BMD of up to 34.5% 1-year postoperative, indicating remineralization. No recurrence was observed. In conclusion our data indicates that 68Ga DOTA-TATE PET/CT is an effective and promising diagnostic tool in the diagnosis of TIO, even in patients in whom 111In-OCT prior failed to detect a tumor.