Head-to-Head Comparison between FDG and 11C-Methionine in Multiple Myeloma: A Systematic Review.

The aim of this systematic review is to provide a comprehensive overview of the existing literature, comparing 18F-fluorodeoxyglucose (FDG) and 11C-methionine (MET) for the imaging of multiple myeloma (MM) with positron emission computed tomography (PET/CT). Relevant studies published from 2013 up to March 2023 were selected by searching Scopus, PubMed, and Web of Science. Selected imaging studies were analyzed using a modified version of the critical Appraisal Skills Programme (CASP). Ten studies encompassing 335 patients were selected. On a patient-based analysis, MET sensitivity ranged between 75.6% and 100%, resulting higher than that measured for FDG (0-100%). MET outperformed FDG for the detection of focal lesions, diffuse bone marrow involvement and mixed patterns. PET-derived parameters resulted higher for MET than for FDG, with a strong correlation with clinical variables (e.g., monoclonal component and beta-2-microglobulin levels, bone marrow infiltration, etc.), although FDG maintained a prognostic impact on outcome prediction. When compared to other tracers or imaging modalities, MET showed stronger correlation and inter-observer agreement than FDG. Although biased by the small cohorts and requiring confirmation through multicenter studies, preliminary findings suggest that MET-PET should be preferred to FDG for PET imaging of MM, or alternatively used as a complementary imaging modality. Some issues, such as tracer availability and the role of MET with respect to other emerging tracers (i.e., 68Ga-pentixafor, 18F-FACBC and 18F-FET), should be the topic of further investigations.

Clinical Applications of TSPO PET for Glioma Imaging: Current Evidence and Future Perspective-A Systematic Review.

Our aim was to provide a comprehensive overview of the existing literature concerning the clinical applications of positron emission computed tomography (PET) with radiopharmaceuticals targeting the translocator protein (TSPO) in gliomas. A literature search for studies about TSPO PET in the last 10 years (from 2013 to February 2023) was carried out on PubMed, Scopus, and Web of Science using the following keywords: "PET" AND "Gliomas" AND "TSPO". The Critical Appraisal Skills Program checklist for diagnostic test studies was used for testing the quality of selected papers. Ten articles were selected, encompassing 314 glioma patients submitted to PET/CT (9/10) or PET/MRI (1/10) with TSPO ligands. Among the various available TSPO tracers, the most frequently used was the third-generation ligand, [18F]-GE-180. TSPO PET results were useful to identify anaplastic transformation in gliomas and for the prognostic stratification of patients bearing homogeneous genetic alterations. When compared to amino-acid PET, TSPO PET with [18F]-GE-180 presented superior image quality and provided larger and only partially overlapping PET-based volumes. Although biased by some issues (i.e., small sample size, most of the studies coming from the same country), preliminary applications of TSPO PET were encouraging. Further studies are needed to define implications in clinical practice and shape the role of TSPO PET for patients' selection for potential TSPO-targeted molecular therapies.

Usefulness of 99mTc-Pertechnetate SPECT-CT in Thyroid Tissue Volumetry: Phantom Studies and a Clinical Case Series.

BACKGROUND: An accurate measurement of the target volume is of primary importance in theragnostics of hyperthyroidism. OBJECTIVE: Our purpose was to evaluate the accuracy of a threshold-based isocontour extraction procedure for thyroid tissue volumetry from SPECT-CT. METHODS: Cylindrical vials with a fixed volume of 99mTcO4 at different activities were inserted into a neck phantom in two different thickness settings. Images were acquired by orienting the phantom in different positions, i.e., 40 planar images and 40 SPECT-CT. The fixed values of the isocontouring threshold for SPECT and SPECT-CT were calculated by means of linear and spline regression models. Mean, Median, Standard Deviation, Standard Error, Mean Absolute Percentage Error and Root Mean-Square Error were computed. Any difference between the planar method, SPECT and SPECT-CT and the effective volume was evaluated by means of ANOVA and posthoc tests. Moreover, planar and SPECT-CT acquisitions were performed in 8 patients with hyperthyroidism, considering relevant percentage differences greater than > 20% from the CT gold standard. RESULTS: Concerning phantom studies, the planar method shows higher values of each parameter than the other two methods. SPECT-CT shows lower variability. However, no significant differences were observed between SPECT and SPECT-CT measurements. In patients, relevant differences were found in 7 out of 9 lesions with the planar method, in 6 lesions with SPECT, but in only one with SPECT-CT. CONCLUSION: Our study confirms the superiority of SPECT in volume measurement if compared with the planar method. A more accurate measurement can be obtained from SPECT-CT.

Sequencing radium 223 and other life-prolonging agents in castration-resistant prostate cancer patients.

Background: Radium 223 (RA223) is currently administered as part of a therapeutic sequence with the other life-prolonging agents (LPAs) for metastatic castration-resistant prostate cancer (mCRPC). Patients & methods: We retrospectively reviewed the clinical records of patients who had received at least three LPAs including RA223. Results: Median overall survival (OS) from the start of first-line treatment was 39.8 months, with the patients who completed all six planned courses of RA223 having a longer OS than those who did not (53.2 vs 29.5 months; p < 0.0001). Conclusions: Our study confirms the activity of RA223 regardless of the treatment line in which it is administered and suggests that patient selection plays a central role in maximizing this activity.

Diagnostic Value of the Early Heart-to-Mediastinum Count Ratio in Cardiac 123I-mIBG Imaging for Parkinson's Disease.

BACKGROUND: Early diagnosis of Parkinson's disease (PD) is of primary importance. The delayed (3-4 h after injection) Iodine-123-Metaiodobenzylguanidine (123I-mIBG) scintigraphy has been proven to be effective in early differential diagnosis for Lewy body disease. But early imaging (15-30 min after injection) has only been marginally studied for its possible diagnostic role. In this prospective study, a threshold for the early Heart-to-Mediastinum (H/M) count ratio has been investigated, obtaining a diagnostic accuracy analogous to conventional, delayed imaging. METHODS: One hundred and eight patients with suspected Parkinson's disease (PD) were acquired after 15 and 240 minutes from the injection of 150-185 MBq of 123I-mIBG. The early and late H/M (He/Me and Hl/Ml) were evaluated by drawing Region-of-Interests on the heart and the upper half of the mediastinum. Optimal threshold (Youden index) and overall predictive performance were determined by receiver operating characteristic curve, classifying tentatively patients having an Hl/Ml lower than 1.6 as suffering from PD. RESULTS: He/Me was not significantly different from Hl/Ml (p-value=0.835). The Area-under-curve was 0.935 (95%CI: 0.845-1.000). The He/Me optimal threshold was 1.66, with sensitivity, specificity, and diagnostic accuracy of 95.5%, 85.7 and 90.7% respectively. CONCLUSION: The He/Me Ratio is almost as accurate as the widely used delayed 123I-mIBG imaging, reducing the burden of delayed imaging but preserving the diagnostic accuracy of the method. Moreover the differential diagnosis in Parkinson's disease can be made in just 25 minutes against the 4 hours currently needed, lowering costs of the healthcare system and improving patients compliance.

Usefulness of 5 Minutes 123I-mIBG Scan in Parkinson's Disease and Heart Failure.

BACKGROUND: The use of 123I-mIBG has been approved for decades for Parkinson's disease (PD) diagnosis and as a predictor of mortality and potentially fatal events in patients with Heart Failure (HF). The standardized technique includes an early acquisition (15 minutes from injection), and a late acquisition (240 minutes). Early images mainly represent interstitial uptake, whereas delayed images represent actual neuronal uptake, however, it is reasonable to affirm that different pathological situations, such as PD and HF, imply a different meaning for early and late imaging. OBJECTIVE: This prospective study aims to investigate the clinical usefulness of an immediate planar 123I-mIBG image acquisition (5 minutes) both in patients with PD and in patients with HF. METHODS: 115 patients referred to 123I-mIBG cardiac imaging in Nuclear Medicine Center have been enrolled (60 patients with PD, absence of diabetes and/or cardiologic pathology, Hoehn e Yahr classification ≤ 1.5; 55 patients with cardiomyopathy, diagnosis of HF, NYHA class I-III). 123I-mIBG planar anterior thoracic acquisitions were performed after 5 (immediate), 15 (early) and 240 (late) minutes from injection and H/M ratios were calculated. RESULTS: In PD group H/M mean values resulted in 1.58±0.22 for immediate (5 min), 1.61±0.26 for early (15 min) and 1.59±0.37 for late (240 min) acquisitions. In the HF group, H/M mean values resulted in 1.63±0.24 for immediate (5 min), 1.65±0.22 for early (15 min) and 1.57±0.17 for late (240 min) acquisitions, respectively. H/M values obtained at 5 min and 15 min are provided similar results, with no statistical difference (p = ns) regardless of the pathology examined (PD or HF groups). The statistical analyses validated the diagnostic role of immediate acquisition (5 min) and early acquisition (15 min) in PD group as compared to the standardized late acquisition (240 min). On the contrary, in HF group, immediate and early acquisition, as compared to late acquisition (240 min), is not validated as a major cardiac events predictor. CONCLUSION: Our results indicate the potential role of immediate (5 min) or early (15 min) acquisition in replacement of standardized 240 minutes acquisition in PD patients, but this result is not confirmed in HF patients, in which the acquisition at 240 min is confirmed as the most affordable timing for image interpretation, emphasizing the different pathophysiology that underlies these two pathologies.

Scintigraphic load of bone disease evaluated by DASciS software as a survival predictor in metastatic castration-resistant prostate cancer patients candidates to 223RaCl treatment.

Background Aim of our study was to assess the load of bone disease at starting and during Ra-223 treatment as an overall survival (OS) predictor in metastatic castration-resistant prostate cancer (mCRPC) patients. Bone scan index (BSI) is defined as the percentage of total amount of bone metastasis on whole-body scintigraphic images. We present a specific software (DASciS) developed by an engineering team of "Sapienza" University of Rome for BSI calculation. Patients and methods 127 mCRPC patients bone scan images were processed with DASciS software, and BSI was tested as OS predictor. Results 546 bone scans were analyzed revealing that the extension of disease is a predictor of OS (0-3% = 28 months of median survival (MoMS]; 3%-5% = 11 MoMS, > 5% = 5 MoMS). BSI has been analyzed as a single parameter for OS, determining an 88% AUC. Moreover, the composition between the BSI and the 3-PS (3-variable prognostic score) determines a remarkable improvement of the AUC (91%), defining these two parameters as the best OS predictors. Conclusions This study suggests that OS is inversely correlated with the load of bone disease in mCRPC Ra-223-treated subjects. DASciS software appears a promising tool in identifying mCRPC patients that more likely take advantage from Ra-223 treatment. BSI is proposed as a predictive variable for OS and included to a multidimensional clinical evaluation permits to approach the patients' enrollment in a rational way, allowing to enhance the treatment effectiveness together with cost optimization.

18F-Facbc in Prostate Cancer: A Systematic Review and Meta-Analysis.

Trans-1-amino-3-18F-fluorocyclobutanecarboxylic-acid (anti-[18F]-FACBC) has been approved for the detection of prostate cancer (PCa) in patients with elevated prostate-specific-antigen following prior treatment. This review and meta-analysis aimed to investigate the diagnostic performance of 18F-FACBC positron emission tomography/computed-tomography (PET/CT) in the detection of primary/recurrent PCa. A bibliographic search was performed including several databases, using the following terms: "FACBC"/"fluciclovine" AND "prostate cancer"/"prostate" AND "PET"/"Positron Emission Tomography". Fifteen and 9 studies were included in the systematic reviews and meta-analysis, respectively. At patient-based analysis, the pooled sensitivity and specificity of 18F-FACBC-PET/CT for the assessment of PCa were 86.3% and 75.9%, respectively. The pooled diagnostic odds-ratio value was 16.453, with heterogeneity of 30%. At the regional-based-analysis, the pooled sensitivity of 18F-FACBC-PET/CT for the evaluation of primary/recurrent disease in the prostatic bed was higher than in the extra-prostatic regions (90.4% vs. 76.5%, respectively); conversely, the pooled specificity was higher for the evaluation of extra-prostatic region than the prostatic bed (89% vs. 45%, respectively). 18F-FACBC-PET/CT seems to be promising in recurrent PCa, particularly for the evaluation of the prostatic bed. Additional studies to evaluate its utility in clinical routine are mandatory.

High resolution scintimammography helps in differentiating benign from malignant findings in scintigraphic hot spots.

Several efforts have been focusing on the development of detectors devoted to high solution (99m)Tc sestamibi scintimammography to improve sensitivity for non palpable lesions. To this aim new high resolution scintillation gamma camera was developed under the "Integiated Mammographic Imaging" project. The gamma camera, made by CAEN and Pol.Hi.Tech, has an overall dimension of 112x120x75mm3. It consists of an array of 1 in. PSPMTs Hamamatsu H8520-C12 closely packed, a NaI(T1) scintillation array (1.8x1.8x6mm(3) pixel) and a general purpose collimator. By this gamma camera a clinical experience on a few patients with breast cancer suspicion was performed. In this paper we show how high resolution approach allows to better categorize the lesions on the basis of the morphology of the spatial distribution of the radiotracer in the breast tissue. By comparing conventional and high resolution images of a young patient (29 y.o.) with breast cancer suspicion, it appears clear how the Anger, camera images showed a defined hot spot, highly suggestive of malignant lesion; on the contrary, the high resolution scan shown a large and inhomogeneous uptake area with the absence of clear and focal character of the uptake, to be considered as a probably non malignant lesions. This resuh was confirmed by byoptical findings that diagnosed the echographic findings as a benign inflammatory lesion.

Principal component analysis of scintimammographic images.

The recent development of new gamma imagers based on scintillation array with high spatial resolution, has strongly improved the possibility of detecting sub-centimeter cancer in Scintimammography. However, Compton scattering contamination remains the main drawback since it limits the sensitivity of tumor detection. Principal component image analysis (PCA), recently introduced in scintimam nographic imaging, is a data reduction technique able to represent the radiation emitted from chest, breast healthy and damaged tissues as separated images. From these images a Scintimammography can be obtained where the Compton contamination is "removed". In the present paper we compared the PCA reconstructed images with the conventional scintimammographic images resulting from the photopeak (Ph) energy window. Data coming from a clinical trial were used. For both kinds of images the tumor presence was quantified by evaluating the t-student statistics for independent sample as a measure of the signal-to-noise ratio (SNR). Since the absence of Compton scattering, the PCA reconstructed images shows a better noise suppression and allows a more reliable diagnostics in comparison with the images obtained by the photopeak energy window, reducing the trend in producing false positive.