Pheochromocytomas and paragangliomas are characterized by two key features: endocrine disorders with excessive catecholamine secretion and a hereditary or metastatic nature, making early diagnosis and treatment crucial. This clinical practice guideline is a revision of the 2018 edition, which considers recent advances in clinical practice and changes to the health insurance coverage in Japan. Patients presenting with symptoms such as palpitations, headaches, hypertension, or abdominal tumors should undergo screening and confirmation with measurement of fractionated catecholamines and their metabolites in the blood and urine. When the tumor is located in the adrenal glands, it is diagnosed as a pheochromocytoma; when it is located outside the adrenal gland and confirmed by 123I-MIBG scintigraphy or 18F-FDG PET, it is diagnosed as a paraganglioma. Treatment begins with inhibiting catecholamine action using α-blockers, and if that is insufficient, metyrosine is used in combination, followed by laparoscopic tumor removal. Given the metastatic potential, long-term postoperative follow-up is essential. Even in cases of metastasis, tumor debulking should be considered. Treatment options are selected based on the amount of remaining tumor, symptom severity, and lesion progression, including CVD chemotherapy or radionuclide therapies such as 131I-MIBG or 177Lu-DOTATATE. Genetic testing guides the management of different variants, and significant progress has been made in molecularly targeted drug trials. Therefore, further advances in individualized and long-term management are required.

To explore stem-cell-targeted radioimmunotherapy with α-particles in acute myelogenous leukemia (AML), pharmacokinetics and dosimetry of the ²¹¹At-labeled anti-C-X-C chemokine receptor type 4 monoclonal antibody (²¹¹At-CXCR4 mAb) were conducted using tumor xenografted mice. The biological half-life of ²¹¹At-CXCR4 mAb in blood was 15.0 h. The highest tumor uptake of 5.05%ID/g with the highest tumor-to-muscle ratio of 8.51 ± 6.14 was obtained at 6 h. Radiation dosimetry estimated with a human phantom showed absorbed doses of 0.512 mGy/MBq in the bone marrow, 0.287 mGy/MBq in the kidney, and <1 mGy/MBq in other major organs except bone. Sphere model analysis revealed 22.8 mGy/MBq in a tumor of 10 g; in this case, the tumor-to-bone marrow and tumor-to-kidney ratios were 44.5 and 79.4, respectively. The stem-cell-targeted α-particle therapy using ²¹¹At-CXCR4 mAb for AML appears possible and requires further therapeutic studies.

Therapeutic response is evaluated using the diameter of tumors and quantitative parameters of 2-[¹⁸F] fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET). Tumor response to molecular-targeted drugs and immune checkpoint inhibitors is different from conventional chemotherapy in terms of temporal metabolic alteration and morphological change after the therapy. Cancer stem cells, immunologically competent cells, and metabolism of cancer are considered targets of novel therapy. Accumulation of FDG reflects the glucose metabolism of cancer cells as well as immune cells in the tumor microenvironment, which differs among patients according to the individual immune function; however, FDG-PET could evaluate the viability of the tumor as a whole. On the other hand, specific imaging and cell tracking of cancer cell or immunological cell subsets does not elucidate tumor response in a complexed interaction in the tumor microenvironment. Considering tumor heterogeneity and individual variation in therapeutic response, a radiomics approach with quantitative features of multimodal images and deep learning algorithm with reference to pathologic and genetic data has the potential to improve response assessment for emerging cancer therapy.

Objective Gamma camera-based measurement of glomerular filtration rate (GFR) with ^99mTc-diethylenetriaminepentaacetic acid (DTPA) is an established non-invasive measurement of split renal function; however, it is not as accurate as the plasma sample method. Therefore, study into improving the accuracy of such method is clinically relevant. The aim of this study was to elucidate the feasibility of gamma camera-based GFR measurement using renal depth evaluated by lateral scan of ^99mTc-DTPA renography and comparing the results with those of GFR using renal depth measured by CT, and three representative formulas. Methods The study population comprised 38 patients (median, 69 years; male 28, female 10; median estimated GFR, 67.4 ml/min) with renourinary disorders. Scintigraphy was performed after intravenous injection of 370 MBq ^99mTc-DTPA by dynamic data acquisition for 20 min, followed by a bilateral static scan of the abdomen for 3 min. All patients underwent computed tomography (CT) within 2 months from renography. GFR was calculated by renography using renal depth determined in five ways; lateral scan of ^99mTc-DTPA, CT, and three formulas previously created with using weight, height and age. GFRs were compared with estimated GFR (eGFR). The depth of both kidneys measured as described above was compared and evaluated the laterality of the renal depth. Results The median values of GFR calculated with renal depth determined by ^99mTc-DTPA renography, CT, and the three formulas were 87.3, 83.9, 67.8, 68.3, and 71.5 ml/min, respectively. All of them correlated significantly with eGFR (r = 0.734, r = 0.687, r = 0.728, r = 0.726, and r = 0.686, respectively), however, no significant difference was observed among five correlation coefficients. Bland–Altman plot revealed that eGFR had error and fixed bias when compared with GFRs calculated using renal depth determined by renography, CT, and Taylor’s formula. The depth of both kidneys measured by ^99mTc-DTPA renography was equivalent to that measured by CT, however, those measured by the three formulas were significantly smaller than that measured by ^99mTc-DTPA renography. The depth of the right kidney was larger than that of the left kidney using all three formulas in all patients. However, CT detected only 66% of patients to have a deeper right kidney than left kidney. Conclusion Lateral scanning is a feasible procedure to measure renal depth for accurate and reasonable split GFR measurements using ^99mTc-DTPA renography.

Background/Aim: L-[3-¹⁸F]-α-methyl tyrosine (¹⁸F-FAMT) positron emission tomography (PET) has a high specificity for detecting malignant lesions. However, the usefulness of therapeutic monitoring of ¹⁸F-FAMT PET against advanced human neoplasms remains unclear. Here, we evaluated ¹⁸F-FAMT PET clinical significance regarding therapy response and outcome after systemic chemotherapy in patients with advanced lung cancer, compared to ¹⁸F-FDG PET. Patients and Methods: All patients with untreated advanced lung cancer received ¹⁸F-FAMT PET and ¹⁸F-FDG PET before and 4 weeks after one cycle of chemotherapy. Metabolic response (MR) was defined according to the PERCIST guideline. Results: Ninety-five patients were eligible for analysis on both PET scans. The histological type included 87 non-small cell lung cancers and 8 small-cell lung cancers. Post-treatment maximal standardized uptake values (SUV_max) and MR on ¹⁸F-FAMT PET were correlated with tumor response. In all patients, post-treatment SUV_max of ¹⁸F-FDG and ¹⁸F-FAMT PET and MR of ¹⁸F-FAMT PET were statistically significant prognostic markers for predicting poor outcome by univariate analysis. Multivariate analysis confirmed that MR on ¹⁸F-FAMT PET was a significant independent prognostic factor. Conclusion: MR on ¹⁸F-FAMT PET may be a potential parameter to predict the prognosis after first-line chemotherapy in patients with advanced lung cancer.

Evaluation of cancer therapy with imaging is crucial as a surrogate marker of effectiveness and survival. The unique response patterns to therapy with immune-checkpoint inhibitors have facilitated the revision of response evaluation criteria using FDG-PET, because the immune response recalls reactive cells such as activated T-cells and macrophages, which show increased glucose metabolism and apparent progression on morphological imaging. Cellular metabolism and function are critical determinants of the viability of active cells in the tumor microenvironment, which would be novel targets of therapies, such as tumor immunity, metabolism, and genetic mutation. Considering tumor heterogeneity and variation in therapy response specific to the mechanisms of therapy, appropriate response evaluation is required. Radiomics approaches, which combine objective image features with a machine learning algorithm as well as pathologic and genetic data, have remarkably progressed over the past decade, and PET radiomics has increased quality and reliability based on the prosperous publications and standardization initiatives. PET and multimodal imaging will play a definitive role in personalized therapeutic strategies by the precise monitoring in future cancer therapy.