11C-methionine PET/CT and conventional imaging techniques in the diagnosis of primary hyperparathyroidism.

Background: It is well known that primary hyperparathyroidism (PHPT) is one of the most common endocrine disorders. Precise preoperative adenoma localization is essential for increasing PHPT cure rate. Conventional localization techniques include neck ultrasound, 99m-Tc-sestamibi scintigraphy, and computed tomography (CT). However, all of these methods have limitations. 11C-methionine positron emission tomography/computed tomography (PET/CT) combines both anatomical and functional modalities; it may be useful in terms of lowering the imaging procedures number and improving accuracy. Methods: A retrospective diagnostic accuracy study with sensitivity and specificity evaluation was conducted. We studied the data of 91 patients with PHPT, who were hospitalized at Almazov National Medical Research Centre. Medical records, lab results, and CT imaging of all patients were analyzed. All of them underwent ultrasound. 99m-Tc-sestamibi/99m-Tc-pertechnetate subtraction scintigraphy and CT were performed on 56 and 86 patients, respectively. Since 2020 11C-methionine PET/CT has been performed on 45 patients. Then, minimally invasive parathyroidectomy (PTX) was carried out in all patients. Histological results were used as a benchmark in order to evaluate diagnostic accuracy of studied methods. Parathyroid adenoma or hyperplasia was confirmed in all patients. Multiple lesions were found in 5 patients. Nineteen lesions were ectopic. All patients with multiple lesions required at least 3 localization techniques, and 2 of them required 4. Results: The sensitivity of 11C-methionine PET/CT was 98%, CT, 99m-Tc-sestamibi scintigraphy, and ultrasound showed sensitivity at 75%, 79%, and 67%, respectively. The estimated specificities of 11C-methionine PET/CT, CT, 99m-Tc-sestamibi scintigraphy and ultrasound were 93%, 73%, 75%, and 70%, respectively. Conclusions: Our study showed that 11C-methionine PET/CT has higher sensitivity and specificity than conventional techniques in a group of 19 patients. 11C-methionine PET/CT may take a place in the imaging of parathyroid adenomas, it may replace CT and 99m-Tc-sestamibi scintigraphy while simultaneously providing information about lesion topography and function.

Preclinical Characterisation of PSMA/GRPR-Targeting Heterodimer [68Ga]Ga-BQ7812 for PET Diagnostic Imaging of Prostate Cancer: A Step towards Clinical Translation.

The development of radioligands targeting prostate-specific membrane antigen (PSMA) and gastrin-releasing peptide receptor (GRPR) has shown promising results for the imaging and therapy of prostate cancer. However, studies have shown that tumors and metastases can express such targets heterogeneously. To overcome this issue and to improve protein binding, radioligands with the ability to bind both PSMA and GRPR have been developed. Herein, we present the preclinical characterization of [68Ga]Ga-BQ7812; a PSMA/GRPR-targeting radioligand for the diagnostic PET imaging of prostate cancer. This study aimed to evaluate [68Ga]Ga-BQ7812 to promote the translation of such imaging probes into the clinic. [68Ga]Ga-BQ7812 demonstrated rapid and specific binding to both targets in a PSMA/GRPR-expressing PC3-pip cell line. Results from the biodistribution study in PC3-pip xenografted mice showed specific binding to both targets, with the highest activity uptake at 1 h pi in tumor (PSMA+/GRPR+, 10.4 ± 1.0% IA/g), kidneys (PSMA+, 45 ± 16% IA/g), and pancreas (GRPR+, 5.6 ± 0.7% IA/g). At 3h pi, increased tumour-to-organ ratios could be seen due to higher retention in the tumor compared with other PSMA or GRPR-expressing organs. These results, together with low toxicity and an acceptable estimated dosimetry profile (total effective dose = 0.0083 mSv/MBq), support the clinical translation of [68Ga]Ga-BQ7812 and represent a step towards its first clinical trial.

Dual-tracer PET/CT imaging to determine tumor heterogeneity in a patient with metastatic ACTH-secreting neuroendocrine neoplasm: A case report and literature review.

Introduction: We present a case of a patient with disseminated ACTH-secreting neuroendocrine neoplasm with biologic heterogeneity between a primary tumor and metastases. The diagnosis was obtained and multidisciplinary management was conducted with a positron emission tomography/computed tomography (PET/CT) scan with Gallium-68 [68Ga]-labeled dodecanetetraacetic acid-tyrosine-3-octreotate ([68Ga]-DOTA-TATE) and Fluor-18 [18F]-fluorodeoxyglucose ([18F]-FDG). Case report: A PET/CT scan revealed a difference between [68Ga]-DOTA-TATE and [18F]-FDG uptake in primary tumor and several metastases. PET/CT showed high [18F]-FDG uptake and lack of [68Ga]-DOTA-TATE in the primary tumor, whereas both [68Ga]-DOTA-TATE and [18F]-FDG hyperaccumulation were identified in the majority of metastases. Despite positive [68Ga]-DOTA-TATE PET/CT, which is associated with high affinity with the somatostatin receptor 2 subtype, immunohistochemical examination revealed overexpression of the somatostatin receptor 5 subtype only. Perhaps, this explained the ineffectiveness of the treatment with "cold" somatostatin analogs. Conclusion: This case had an aggressive clinical course, despite cytoreductive surgical treatment and somatostatin analog therapy. PET/CT imaging with two tracers is a molecular tool that demonstrates a biologic heterogeneity between a primary tumor and metastases and yields additional information that may influence the choice of the patient management strategy.

Case Report: Primary Leptomeningeal Medulloblastoma in a Child: Clinical Case Report and Literature Review.

Medulloblastoma is one of the most common pediatric central nervous system malignancies worldwide, and it is characterized by frequent leptomeningeal metastasizing. We report a rare case of primary leptomeningeal medulloblastoma of an 11-year-old Caucasian girl with a long-term disease history, non-specific clinical course, and challenges in the diagnosis verification. To date, 4 cases of pediatric primary leptomeningeal medulloblastoma are reported, and all of them are associated with unfavorable outcomes. The approaches of neuroimaging and diagnosis verification are analyzed in the article to provide opportunities for effective diagnosis of this disease in clinical practice. The reported clinical case of the primary leptomeningeal medulloblastoma is characterized by MR images with non-specific changes in the brain and spinal cord and by 18FDG-PET/CT images with diffuse heterogeneous hyperfixation of the radiopharmaceutical along the whole spinal cord. The immunohistochemistry and next-generation sequencing analyses of tumor samples were performed for comprehensive characterization of the reported clinical case.

The coincidence of two rare diseases with opposite metabolic phenotype: a child with congenital hyperinsulinism and Bloom syndrome.

OBJECTIVES: Congenital hyperinsulinism (CHI) is a group of rare genetic disorders characterized by insulin overproduction. CHI causes life-threatening hypoglycemia in neonates and infants. Bloom syndrome is a rare autosomal recessive disorder caused by mutations in the BLM gene resulting in genetic instability and an elevated rate of spontaneous sister chromatid exchanges. It leads to insulin resistance, early-onset diabetes, dyslipidemia, growth delay, immune deficiency and cancer predisposition. Recent studies demonstrate that the BLM gene is highly expressed in pancreatic islet cells and its mutations can alter the expression of other genes which are associated with apoptosis control and cell proliferation. CASE PRESENTATION: A 5-month-old female patient from consanguineous parents presented with drug-resistant CHI and dysmorphic features. Genetic testing revealed a homozygous mutation in the KCNJ11 gene and an additional homozygous mutation in the BLM gene. While 18F-DOPA PET scan images were consistent with a focal CHI form and intraoperative frozen-section histopathology was consistent with diffuse CHI form, postoperative histopathological examination revealed features of an atypical form. CONCLUSIONS: In our case, the patient carries two distinct diseases with opposite metabolic phenotypes.

Differential Morphological Diagnosis of Various Forms of Congenital Hyperinsulinism in Children.

Introduction: Congenital hyperinsulinism (CHI) has diffuse (CHI-D), focal (CHI-F) and atypical (CHI-A) forms. Surgical management depends on preoperative [18F]-DOPA PET/CT and intraoperative morphological differential diagnosis of CHI forms. Objective: to improve differential diagnosis of CHI forms by comparative analysis [18F]-DOPA PET/CT data, as well as cytological, histological and immunohistochemical analysis (CHIA). Materials and Methods: The study included 35 CHI patients aged 3.2 ± 2.0 months; 10 patients who died from congenital heart disease at the age of 3.2 ± 2.9 months (control group). We used PET/CT, CHIA of pancreas with antibodies to ChrA, insulin, Isl1, Nkx2.2, SST, NeuroD1, SSTR2, SSTR5, DR1, DR2, DR5; fluorescence microscopy with NeuroD1/ChrA, Isl1/insulin, insulin/SSTR2, DR2/NeuroD1 cocktails. Results: Intraoperative examination of pancreatic smears showed the presence of large nuclei, on average, in: 14.5 ± 3.5 cells of CHI-F; 8.4 ± 1.1 of CHI-D; and 4.5 ± 0.7 of control group (from 10 fields of view, x400). The percentage of Isl1+ and NeuroD1+endocrinocytes significantly differed from that in the control for all forms of CHI. The percentage of NeuroD1+exocrinocytes was also significantly higher than in the control. The proportion of ChrA+ and DR2+endocrinocytes was higher in CHI-D than in CHI-F, while the proportion of insulin+cells was higher in CHI-A. The number of SST+cells was significantly higher in CHI-D and CHI-F than in CHI-A. Conclusion: For intraoperative differential diagnosis of CHI forms, in addition to frozen sections, quantitative cytological analysis can be used. In quantitative immunohistochemistry, CHI forms differ in the expression of ChrA, insulin, SST and DR2. The development of a NeuroD1 inhibitor would be advisable for targeted therapy of CHI.