Hellenic journal of nuclear medicine最新文献

Multiple myeloma (MM) is a neoplastic disease characterized by the proliferation of clonal plasma cells. This disease arises from an initial asymptomatic stage known as monoclonal gammopathy of unknown significance (MGUS). The clinical phenotype that lies between MGUS and MM is commonly known as smoldering multiple myeloma (SMM). In individuals with MGUS and SMM, the risk of progression to MM persists constantly. In MGUS, the progression rate to MM or a related malignancy is around 1% per year, while in SMM, the progression rate to MM is approximately 10% per year. Recently, myeloma was defined as a clonal proliferation of malignant plasma cells that results in end organ damage or myeloma-defining events. MM is a genetically complex disease that exhibits clinical and biological diversity. Currently, the revised International Staging System (R-ISS) is used for prognostication in newly diagnosed patients. For transplant-eligible patients with newly diagnosed MM, the standard of care treatment (SoC) regimen is induction therapy, followed by ASCT and maintenance therapy. In general, the recommended induction therapy is a triplet or quadruplet-agent therapy consisting of a proteasome inhibitor, an immunomodulatory compound, and/or a CD38 antibody in combination with dexamethasone. Myeloma patients who are ineligible for a transplant are typically treated with a triplet combination, which necessitates specialized knowledge of treatment adverse effects. Although the prognosis for patients with MM has significantly improved over time due to advances in treatment, the disease remains incurable and relapses are common. Because various immunotherapeutic agents, new drugs and combinations have become available, selecting the most effective treatment for patients with relapsed/refractory MM needs both art and science.

Nuclear cardio-oncology is a specialized field that combines aspects of nuclear medicine, cardiology, and oncology to diagnose and manage cardiovascular complications in cancer patients. It focuses on the assessment of cardiovascular health and the detection of potential heart-related side effects caused by cancer treatments.

Introduction: Personalized dosimetry is tending to become the "gold standard" in Molecular Radiotherapy (MRT). Setting up carefully all the procedures involved in the workflow is crucial for the final clinical result.

Aim: Individualized MRT dosimetry using a recently installed commercial system, comprising of a dual SPECT/CT camera, a treatment planning software (TPS) and a dose calibrator was implemented on patients undergoing ¹⁷⁷Lu-DOTATATE and ¹⁷⁷Lu-PSMA therapies. The clinical workflow implemented in our department is presented in detail. Measurement and calculation of the Calibration Factor (CF) to translate the count rate into activity concentration (quantitative data), and system's commissioning, was discussed.

Materials and methods: Calibration of the dose calibrator, the SPECT/CT system and the TPS, measured using the clinical acquisition protocol, were analyzed along with potential errors introduced by the procedure and means of future optimization. In addition, image acquisition parameters, image reconstruction and image registration were discussed. Anatomical contouring of the organs at risk (OARs) and functional contouring of the lesions, followed by the dose calculation of the aforementioned structures, with the use of different calculation algorithms, were presented, compared and evaluated.

Results and discussion: According to our experience, different fitting of each organ's activity curve, results in differences in the final calculated dose. Use of bi-exponential fitting seems to better approach physical and metabolic decay. Calculated absorbed doses for the OARs were found similar to those expected from literature. Finally, department's future work was discussed, including reproducible patient setup for image acquisition, high dose CT for finer contouring and comparison of the calculated doses with other TPSs.

Histological diagnosis is mandatory for the majority of solid lesions in the lungs in order to characterize the lesions but also to assess the response to treatment. Flexible bronchoscopy has a variable and often poor success rate in sampling pulmonary lesions which are not visible endoscopically. Such focal radiological opacities without endobronchial extension are referred to as peripheral pulmonary lesions and sampling is usually performed under guidance with computed tomography that is a safe and effective technique and became a common procedure representing an essential step for diagnosis and treatment planning. It is usually performed with an 18G or 20G coaxial needle system and several novel guidance and navigation tools may be integrated to clinical practice to offer more accurate lesion targeting. There is however still a percentage of negative sampling a recent study revealed that small lesion size, lower ¹⁸F-FDG uptake or location at the lung bases may lead to inconclusive histology. The diagnostic yield may be increased if PET/CT fusion imaging is used intraprocedurally. CT guided biopsies may also be applied in the same setup with interventions such as ablation of lung lesions offering a "one-stop" approach for such patients.

Theranostics is an emerging field in medicine that combines diagnostics and therapeutics into a single approach. Overall, theranostics represents a promising paradigm for personalized medicine, as it allows for targeted and precise treatment based on individual patient characteristics. In nuclear medicine, theranostics involves the use of radiopharmaceuticals that have both diagnostic and therapeutic properties. Moreover, theranostics in nuclear medicine offers several advantages over traditional cancer treatments. Unlike radiotherapy, in nuclear medicine the therapy is systemic that targets both primary tumors and metastatic lesions, offering a more comprehensive treatment approach. Additionally, nuclear medicine therapy has been shown to have fewer side effects compared to traditional chemotherapy, making it a more tolerable treatment option for patients. While theranostics in nuclear medicine is still a relatively new field, it has shown promising results in the treatment of neuroendocrine tumors (NETs). One example of a theranostic approach in nuclear medicine is the use of radiolabeled somatostatin analogs for the treatment of NETs. Somatostatin is a hormone that regulates the release of other hormones in the body. It also binds to somatostatin receptors, which are highly expressed in NETs. The first step in theranostics for NETs is the diagnosis and staging of the disease using a radiolabeled somatostatin analog and PET/CT imaging. This allows for the detection of the tumor and assessment of its size and location. Once the tumor has been identified, the same radiolabeled somatostatin analog can be used as a therapeutic agent. The radiopharmaceutical delivers radiation directly to the tumor cells, which destroys them while sparing surrounding healthy tissue. This is known as peptide receptor radionuclide therapy (PRRT). The use of theranostics in NETs also involves the identification of specific somatostatin receptor subtypes that are expressed in the tumor cells. This is important as different somatostatin analogs have varying affinities for different receptor subtypes. By selecting the appropriate radiolabeled somatostatin analog, clinicians can increase the specificity of the therapy, delivering radiation to the tumor cells while minimizing damage to healthy tissue. PRRT has been shown to be effective in treating NETs, particularly those that are resistant to other forms of treatment. It can also be used in combination with other therapies, such as chemotherapy and surgery, to improve outcomes. As research continues, it is likely that theranostics in nuclear medicine will become an increasingly important tool in the fight against cancer, particularly in the context of NETs, offering personalized, targeted treatment options that improve patient outcomes.

Objective: In previous fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) studies, tumor segmentation using peritumoral halo layer (PHL; SegPHL) was shown to be reliable and accurate segmentation method in various malignant tumors. We found that the halo layer also was observed on the ^99mTc-pertechnetate (^99mTcO₄) thyroid single photon emission computed tomography (SPECT)/CT. In the present study, we attempted to apply thyroid segmentation using the perithyroidal halo layer (PTHL; SegPTHL) on ^99mTcO₄ thyroid SPECT/CT and compared SegPTHL with CT-based thyroid segmentation (SegCT).

Subjects and methods: A total of 33 patients (19 females, 14 males; mean age, 46.91±15.7 years old) were enrolled in this study. For SegCT, three-dimensional volume of interest (VOI) of the thyroid was generated via multiple 2-dimensional regions of interest (ROI) along the thyroid margin on transaxial CT images that were manually drawn slice by slice. The PTHL was easily identified by an abrupt increase in layer thickness with minimal or mild distortion of the main thyroid contour, and the thyroid margin for SegPTHL was determined at the innermost portion of PTHL. An automated VOI generation for SegPTHL was performed using the Q. Volumetrix software. The correlation and reliability tests were performed between the quantification parameters of SegPTHL and SegCT.

Results: The PTHL threshold adjusted according to maximal SUV of thyroid were similar to the results of previous SegPHLstudies of ¹⁸F-FDG PET/CT. A good correlation was observed between the thyroid volumes of SegCT and SegPTHL (r=0.725; P<0.0001), although the thyroid volume of SegPTHL was slightly larger than that of SegCT (P=0.0017). The % thyroid uptake (TcTU), total lesion activity (TLA), and mean standardized uptake value (SUVmean) of SegPTHL correlated well with those of SegCT (r=0.9877, 0.9883, 0.9875, respectively; P<0.0001). No significant error was observed between the parameters (i.e., TcTU, TLA, and SUVmean) of SegPTHL and SegCT.

Conclusion: Thyroid segmentation PTHL may be a useful method for reliable quantification of thyroid uptake, because the SPECT/CT parameters of SegPTHL were strongly correlated with those of SegCT, as well as the process of SegPTHL is easier and faster than that of SegCT.

Objective: The purpose of the current study was to evaluatethe diagnostic accuracies of fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) or PET/computed tomography (CT) for diagnosis of myocarditis through and a meta-analysis.

Materials and methods: The PubMed, Cochrane database, and Embase database were searched from inception through November 30, 2022 for studies evaluating diagnostic performance of ¹⁸F-FDG PET or PET/CT for diagnosis of acute myocarditis. Based on data extracted from patient-based analysis, we calculated the pooled sensitivity and specificity with the 95% confidence intervals (CI). Also, we calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic curves.

Results: Across 5 studies (6 results, 264 patients), the pooled sensitivity of ¹⁸F-FDG PET or PET/CT was 0.57 (95% CI; 0.26-0.84) and a pooled specificity of 0.89 (95% CI; 0.74-0.96). Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR+) of 5.1 and negative likelihood ratio (LR-) of 0.48. The pooled DOR was 11 (95% CI; 2-47). In meta-regression analysis, no variable was the source of the study heterogeneity.

Conclusion: Fluorine-18-FDG PET or PET/CT showed insufficient sensitivityand moderate specificity for diagnosis of myocarditis. These results indicated that cautious application of ¹⁸F-FDG PET or PET/CT should be paid for detection of myocarditis.

Objective: Gallium-68-DOTA-D-Phe1-Try3-Octreotide (⁶⁸Ga-DOTATOC) is a radiolabeled somatostatin receptor (SSTR) analog that is widely used in the imaging of neuroendocrine tumors (NET). Benign and malignant prostate tumors have been observed to express SSTR. Diffuse symmetric DOTATOC uptake in the prostate is a normal positron emission tomography (PET) finding. The aim of this study was to evaluate the frequency and clinical significance of incidental atypical prostatic uptake in men undergoing ⁶⁸Ga-DOTATOC PET/computed tomography(CT).

Subjects and methods: A retrospective review of consecutive male patients who underwent ⁶⁸Ga-DOTATOC PET/CT studies at Aalborg University Hospital, Denmark, from November 2010 to April 2020 was performed. Positron emission tomography/CT reports were searched for text words or phrases indicating incidental atypical prostatic uptake. In the resulting cohort, PET/CT were re-evaluated, and DOTATOC uptake in the prostate gland was categorized as focal, diffuse or mixed. The intensity of the uptake was visually graded using the Krenning visual score. Follow-up was based on all available clinical, biochemical, imaging, and pathology follow-up.

Results: A total of 178 male patients underwent 193 ⁶⁸Ga-DOTATOC PET/CT scans. Incidental atypical uptake of ⁶⁸Ga-DOTATOC on PET/CT in the prostatic bed was observed in eight patients (4.5%) (mean age 67 years, range 58-85 years). Six patients (75%) had diffuse uptake; two (25%) patients had focal uptake. Four patients out of eight with incidental findings (50%) had uptake less than or equal to that of the liver (Krenning score 2); four patients (50%) had uptake greater than that of the liver (score 3). All patients had measurements of serum prostate-specific antigen and were referred for urological evaluation. Five patients (62%) underwent a transrectal ultrasound, and three required a biopsy of the prostate. No cases of prostate malignancy (including prostatic cancer) were diagnosed.

Conclusion: During a 10-year period, we found that 4.5% of men exhibited prostate incidentalomas on ⁶⁸Ga-DOTATOC PET/CT. No malignancy was found in the prostate in this population. Our data indicate absent malignancy among incidental ⁶⁸Ga-DOTATOC findings in the prostate.

¹⁸F-FDG PET/CT may facilitate improved diagnosis and treatment in gynecological fields. This method provides pretreatment prognostic information concerning the aggressiveness of tumors which may contribute to optimizing and individualizing patient therapy. Although ¹⁸F-FDG PET/CT has a limited role for local staging of primary cancer, it has an important role in staging, as it aids particularly in identifying the involvement of lymph nodes and distant metastases throughout the whole body in a single examination in patients with advanced-stage disease and also in restaging after therapy. Another major indication of the modality is the evaluation of disease recurrence, especially in clinically equivocal patients or in patients in which tumor markers are rising, and conventional imaging studies show negative or equivocal findings.