Pre-treatment 68 Ga-PSMA-11 PET/CT Prognostic Value in Predicting Response to 177Lu-PSMA-I&T Therapy and Patient Survival.

PURPOSE: To assess the prognostic value of pre-treatment [68Ga]Ga-PSMA-11 PET/CT and other baseline clinical characteristics in predicting prostate cancer (PCa) patients response to [177Lu]Lu-PSMA (PSMA-I&T), as well as patient survival. PROCEDURES: In this retrospective study, 81 patients who received [177Lu]Lu-PSMA-I&T between October 2018 and January 2023 were reviewed. Eligible patients had metastatic castration-resistant PCa, underwent pre-treatment [68Ga]Ga-PSMA-11 PET/CT, and had serum prostate-specific antigen (PSA) levels available. On PET/CT images, SUVmax, SULmax, SUVpeak, and SULpeak of the most-avid tumoral lesion, as well as SUVmean of the parotid gland (P-SUVmean) and liver (L-SUVmean), were measured. Also, whole-body PSMA tumour volume (PSMA-TV) and total lesion PSMA (TL-PSMA) were calculated. To interpret treatment response after [177Lu]Lu-PSMA-I&T, a composite of PSA values and [68Ga]Ga-PSMA-11 PET/CT findings were considered. The outcomes were dichotomised into progressive versus controlled (stable disease or partial response) disease. Then, the association of baseline parameters with patient response was evaluated. Also, survival analyses were performed to assess baseline parameters in predicting overall survival. RESULTS: Sixty patients (age:73 ± 8, PSA:185 ± 371) were included. Patients received at least one cycle of [177Lu]Lu-PSMA therapy (median = 4). Overall, half of the patients showed disease progression. In the progressive versus controlled disease evaluation, the highest SULmax, as well as SUVmax and SULmax to both backgrounds (L-SUVmean and P-SUVmean), were significantly correlated with the outcome (p-values < 0.05). In the multivariate analysis, only SULmax to the L-SUVmean remained significant (p-value = 0.038). The best cut-off was 8 (AUC = 0.71). With a median follow-up of 360 days, 11 mortal events were documented. In the multivariate survival analysis, only SULmax to P-SUVmean (cut-off = 2.4; p-value = 0.043) retained significance (hazard ratio = 4.0). CONCLUSIONS: A greater level of PSMA uptake, specifically higher tumour-to-background uptake in the hottest lesion, may hold substantial prognostic significance, considering both [177Lu]Lu-PSMA-I&T response and patient survival. These ratios may have the potential to be used for PCa patient selection for radioligand therapy.

Head-to-Head Comparison of CZT-SPECT and SPECT/CT Myocardial Perfusion Imaging: Interobserver and Intraobserver Agreement and Diagnostic Performance.

BACKGROUND: Myocardial perfusion imaging (MPI) plays a crucial role in diagnosing coronary artery disease (CAD), with single-photon emission computed tomography (SPECT) being a widely accepted method. The accuracy of MPI relies on image quality and the expertise of physicians. While CZT-SPECT cameras offer advantages, they can be susceptible to attenuation artifacts. Therefore, our objective was to evaluate the diagnostic accuracy of CZT-SPECT and SPECT/CT in a clinical setting. METHOD: We conducted a prospective single-center study involving patients with known or suspected stable ischemic heart disease who underwent SPECT-MPI using CZT-SPECT and SPECT/CT scanners, and the latter was equipped with cardiofocal collimation. Experienced physicians performed analysis and reporting based on automated quantification and visual image interpretation. RESULTS: A total of 77 patients (32 women (41.6%) and 45 men (58.4%) with an average age of 71.9 ± 8.9 years) were included. The agreement between readers regarding the final conclusion based on imaging reporting using both devices was very high (Kappa 0.87-0.93). Per-vessel analysis revealed a trend suggesting that CZT-SPECT was superior to conventional SPECT/CT in terms of sensitivity, positive predictive value (PPV), negative predictive value (NPV), and accuracy, although the difference did not reach statistical significance. CONCLUSION: Our study demonstrated that CZT-SPECT imaging offers comparable diagnostic accuracy, improved patient comfort, and eliminates CT-induced radiation compared to SPECT/CT. These findings suggest that cardiac CZT-SPECT imaging has the potential to become a valuable imaging modality in clinical practice.

Evolving Role of [18F]Flurocholine PET/CT in Assessing Primary Hyperparathyroidism: Can It Be Considered the First-Line Functional Imaging Approach?

The accurate detection of hyperfunctioning parathyroid tissue (HFPT) is pivotal in the preoperative assessment of primary hyperparathyroidism (PHPT). PET/CT using [18F]fluorocholine ([18F]FCH) showed superior diagnostic performance compared to conventional functional imaging modalities. We aimed to evaluate the diagnostic performance of [18F]FCH PET/CT as a first-line functional imaging approach in patients with clinically diagnosed PHPT. The imaging and clinical data of 321 PHPT patients, including 271 overt PHPT and 50 mild PHPT, who underwent [18F]FCH PET/CT as first-line imaging were analysed in this retrospective study. Histopathology was the reference standard. In case of no available histopathology evaluation (conservative management), imaging and clinical follow-ups were considered reference standards. In the overt group (n = 271), [18F]FCH PET/CT showed sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 0.99, 0.91, 1.00, 0.80, and 0.99, respectively. Regarding the correlation of the index lesions and initial laboratory data, all [18F]FCH PET/CT parameters (SUVs, SULs, and mSAD) were significantly correlated with the serum iPTH level. Additionally, SUVmax, SULpeak, and mSAD were significantly associated with the serum calcium level. In the mild group (n = 50), [18F]FCH PET/CT showed a sensitivity, specificity, PPV, NPV, and accuracy of 0.93, 0.75, 0.95, 0.67, and 0.90. In conclusion, [18F]FCH PET/CT revealed high diagnostic performance in the detection of HFPTs and the potential to be considered as a first-line imaging modality in the assessment of PHPT, including both overt and mild types. However, its cost-benefit concerning the clinical impact of early PHPT detection should be investigated in future studies.

A Novel Clinical Score for Differential Diagnosis Between Acute Myocarditis and Acute Coronary Syndrome - The SAlzburg MYocarditis (SAMY) Score.

Background: Acute myocarditis and acute coronary syndrome (ACS) are important differential diagnoses in patients with new-onset chest pain. To date, no clinical score exists to support the differentiation between these two diseases. The aim of this study was to develop such a score to aid the physician in scenarios where discrimination between myocarditis and ACS appears difficult. Materials and Methods: Patients with ACS (n = 233) and acute myocarditis (n = 123) were retrospectively enrolled. Least absolute shrinkage and selection operator (LASSO) regression was conducted to identify parameters associated with the highest or least probability for acute myocarditis. Logistic regression was conducted using the identified parameters and score points for each level of the predictors were calculated. Cutoffs for the prediction of myocarditis were calculated. Validation was conducted in a separate cohort of 90 patients. Results: A score for prediction of acute myocarditis was calculated using six parameters [age, previous infection, hyperlipidemia, hypertension, C-reactive protein (CRP), and leukocyte count]. Logistic regression analysis showed a significant association between total score points and the presence of myocarditis (B = 0.9078, p < 0.0001). Cutoff #1 for the prediction of myocarditis was calculated at ≥ 4 (Sens.: 90.3%, Spec.: 93.1%; 46.3% predicted probability for acute myocarditis), cutoff #2 was calculated at ≥ 7 (Sens.: 73.1%, Spec.: > 99.9%; 92.9% pred. prob.). Validation showed good discrimination [area under the curve (AUC) = 0.935] and calibration of the score. Conclusion: Our clinical score showed good discrimination and calibration for differentiating patients with acute myocarditis and ACS. Thus, it could support the differential diagnosis between these two disease entities and could facilitate clinical decisions in affected patients.

Prognostic value of 2-[18F]FDG PET-CT in metastatic melanoma patients receiving immunotherapy.

PURPOSE: The 2-fluorodeoxyglucose positron emission tomography/computed tomography (2-[18F]FDG PET/CT) is used for the evaluation of response to immunotherapy in malignant melanoma. Here, we evaluated the prognostic value of various metabolic parameters in baseline and different time points after therapy. METHODS: In this retrospective study, 51 metastatic melanoma patients, who had received immunotherapy, were included. Patients with baseline and two follow-up 2-[18F]FDG PET/CT studies (3 and 6 months after therapy) were selected. Multiple metabolic parameters and tumor-to-background ratios (TBRs) were extracted and correlated with OS. RESULTS: The 3- and 5-year OS rates were 49% and 43.1%, respectively. On baseline 2-[18F]FDG PET/CT, only standardized uptake value corrected for lean body mass (SULmax and SULpeak), as well as most of the TBRs were predictive for 3- and 5-year OS rates. Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and most of the TBRs were predictive on both follow-up studies. Also, the changes in values of MTV, TLG and most of the TBRs from the baseline to the 3-month and 6- month follow-up studies were prognostic. On multivariate analysis, all of the most predictive parameters for OS were derived from the 3-month follow-up study. The ratio of TBRmean to the mediastinum was the best factor (cutoff value of 2.15, sensitivity of 88.5% and specificity of 68.0% for 3-year survival). CONCLUSION: Metabolic parameters derived from 2-[18F]FDG PET/CT are valuable tools for the prediction of 3- and 5-year OS rates in metastatic melanoma patients undergoing immunotherapy. The 3-month follow-up 2-[18F]FDG PET/CT is of particular importance in this regard.

Feasibility of equivalent performance of 3D TOF [18F]-FDG PET/CT with reduced acquisition time using clinical and semiquantitative parameters.

BACKGROUND: High-performance time-of-flight (TOF) positron emission tomography (PET) systems have the capability for rapid data acquisition while preserving diagnostic image quality. However, determining a reliable and clinically applicable cut-off of the acquisition time plays an important role in routine practice. This study aimed to assess the diagnostic equivalence of short acquisition time of 57 with routine 75 seconds per bed position (s/BP) of [18F]-fluoro-deoxy-glucose (FDG) PET. Phantom studies applying EARL criteria suggested the feasibility of shortened acquisition time in routine clinical imaging by 3D TOF PET/CT scanners. Ninety-six patients with melanoma, lung or head and neck cancer underwent a standard whole-body, skull base-to-thigh or vertex-to-thigh [18F]-FDG PET/CT examination using the 3D TOF Ingenuity TF PET/CT system (Philips, Cleveland, OH). The [18F]-FDG activity applied was equal to 4MBq per kg body weight. Retrospectively, PET list-mode data were used to calculate a second PET study per patient with a reduced acquisition time of 57 s instead of routine 75 s/BP. PET/CT data were reconstructed using a 3D OSEM TOF algorithm. Blinded patient data were analysed by two nuclear medicine physicians. The number of [18F]-FDG-avid lesions per body region (head&neck, thorax, abdomen, bone, extremity) and image quality (grade 1-5) were evaluated. Semiquantitative analyses were performed by standardized uptake value (SUV) measurements using 3D volume of interests (VOI). The visual and semiquantitative diagnostic equivalence of 214 [18F]-FDG-avid lesions were analysed in the routine standard (75 s/BP) as well as the calculated PET/CT studies with short acquisition time. Statistical analyses were performed by equivalence testing and Bland-Altman plots. RESULTS: Lesion detection rate per patient's body region agreed in > 98% comparing 57 s/BP and 75 s/BP datasets. Overall image quality was determined as equal or superior to 75 s in 80% and 69%, respectively. In the semiquantitative lesion-based analyses, a significant equivalence was found between the 75 s/BP and 57 s/BP PET/CT images both for SUVmax (p = 0.004) and SUVmean (p = 0.003). CONCLUSION: The results of this study demonstrate significant clinical and semiquantitative equivalence between short acquisition time of 57 s/BP and standard 75 s/BP 3D TOF [18F]-FDG PET/CT scanning, which may improve the patient's workflow in routine practice.

Pre-Ablation rhTSH-Stimulated F-18 FDG PET/CT Changes Patient Management in Increased-Risk Thyroid Cancer.

The aim of the study was to evaluate the clinical impact of pre-ablation rhTSH-stimulated fluorine-18 fluorodeoxyglucose (F-18 FDG) PET/CT in addition to post-therapeutic whole body radioiodine scanning in patients with intermediate to high risk differentiated thyroid carcinoma (DTC). This was a retrospective single center study including 73 patients with thyroid cancer (44 females, mean age 43.2±16.2 years, 62% papillary, 31% follicular, 7% poorly differentiated). All patients underwent ablative radioiodine treatment (mean activity: 3661±673 MBq I-131) using rhTSH after thyroidectomy and lymph node (LN) dissection (01/2013-10/2016) and TSH-stimulated F-18 FDG PET/CT (4 MBq/kg body weight, low dose CT). Post-treatment I-131 whole body scan (I-131 WBS) was obtained 9 days afterwards in planar technique and in case of equivocal or abnormal findings using SPECT/CT. Thirty-one patients (42%) showed F-18 FDG avid lesions, 14 patients showed more FDG than iodine positive lesions and 5 patients more iodine positive lesions in I-131 WBS, respectively. Fifty-three patients showed identical F-18 FDG PET/CT and I-131 WBS. The initial treatment plan was changed from follow-up to therapy (surgery, systemic therapy using tyrosine-kinase inhibition) in 11 patients (15%) on the basis of F-18 FDG PET/CT imaging. Six of these 11 patients had papillary thyroid cancer. Three patients with histologically proven LN metastases had stimulated thyroglobulin-levels<2.0 ng/ml. Our study demonstrated a clinical benefit of pre-ablation rhTSH-stimulated F-18 FDG PET/CT imaging in about 20% of patients with intermediate to high risk DTC, leading to change in patient management in 15%.

[Imaging of parathyroid adenomas with F­18 choline PET-CT]. / Darstellung und Lokalisation von Nebenschilddrüsenadenomen mit F­18 Cholin PET/CT.

BACKGROUND: Ultrasound and sestamibi scintigraphy are the recommended standard procedures for initial diagnosis in primary hyperparathyroidism (pHPT). Recently, F­18 choline positron emission tomography computed tomography (choline PET/CT) has been shown promising results for the diagnostic work up of primary hyperparathyroidism (pHPT) suggesting superiority over conventional scintigraphy using Tc99m sestamibi based protocols using planar dual-phase imaging, SPECT or SPECT/CT. METHODS: This review presents the results of F­18 choline PET/CT on the basis of a literature search using the keywords "primary hyperparathyroidism and choline", "primary hyperparathyroidism and PET", "parathyroid adenoma and choline" und "parathyroid adenoma and PET". RESULTS: 6 studies were identified dealing with the diagnostic impact of choline PET/CT. The studies included 5 to 151 patients. Localization of single gland adenomas can be achieved with choline PET/CT in 80 up to 96% of cases. A high sensitivity and accuracy of choline PET/CT imaging is documented even in cases of repeated surgery for recurrent pHPT, in coexistant nodular goiter or in the detection of adenoma in atypical localization. CONCLUSIONS: Using choline PET/CT parathyroid adenoma and probably parathyroid hyperplasia can be exactly localized in most patients with pHPT. Thus, a minimal-invasive surgical procedure is feasible with decreased risk of complications but high success rate in terms of biochemical cure. The diagnostic accuracy in multiglandular disease remains to be established.

18F-Fluorocholine PET/CT in the assessment of primary hyperparathyroidism compared with 99mTc-MIBI or 99mTc-tetrofosmin SPECT/CT: a prospective dual-centre study in 100 patients.

PURPOSE: In this prospective study we compared the accuracy of 18F-fluorocholine PET/CT with that of 99mTc-MIBI or99mTc-tetrofosmin SPECT/CT in the preoperative detection of parathyroid adenoma in patients with primary hyperparathyroidism. We also assessed the value of semiquantitative parameters in differentiating between parathyroid hyperplasia and adenoma. METHODS: Both 18F-fluorocholine PET/CT and 99mTc-MIBI/tetrofosmin SPECT/CT were performed in 100 consecutive patients with biochemical evidence of primary hyperparathyroidism. At least one abnormal focus on either 18F-fluorocholine or 99mTc-MIBI/tetrofosmin corresponding to a parathyroid gland or ectopic parathyroid tissue was considered as a positive finding. In 76 patients with positive findings on at least one imaging modality, surgical exploration was performed within 6 months, and the results were related to histopathological findings and clinical and laboratory findings at 3-6 months as the standard of truth. In 24 patients, no surgery was performed: in 18 patients with positive imaging findings surgery was refused or considered risky, and in 6 patients imaging was negative. Therefore, data from 82 patients (76 undergoing surgery, 6 without surgery) in whom the standard of truth criteria were met, were used in the final analysis. RESULTS: All patients showed biochemical evidence of primary hyperparathyroidism with a mean serum calcium level of 2.78 ± 0.34 mmol/l and parathormone (PTH) level of 196.5 ± 236.4 pg/ml. The study results in 76 patients with verified histopathology and 3 patients with negative imaging findings were analysed. Three of six patients with negative imaging showed normalized serum PTH and calcium levels on laboratory follow-up at 3 and 6 months, and the results were considered true negative. In a patient-based analysis, the detection rate with 18F-fluorocholine PET/CT was 93% (76/82), but was only 61% (50/82) with 99mTc-MIBI/tetrofosmin SPECT/CT. In a lesion-based analysis, the sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy of 18F-fluorocholine PET/CT in the detection of parathyroid adenoma were 93.7%, 96.0%, 90.2%, 97.4% and 95.3%, respectively, and of 99mTc-MIBI/tetrofosmin SPECT/CT were 60.8%, 98.5%, 94.1%, 86.3% and 87.7%, respectively. Although 18F-fluorocholine PET-positive adenomatous lesions showed higher SUVmax values than the hyperplastic glands (6.80 ± 3.78 vs. 4.53 ± 0.40) in the semiquantitative analysis, the difference was not significant (p = 0.236). The mean size (measured as the length of the greatest dimension) and weight of adenomas were 15.9 ± 7.6 mm (median 15 mm, range 1-40 mm) and 1.71 ± 1.86 g (median 1 g, range: 0.25-9 g), respectively. Among the analysed parameters including serum calcium and PTH and the size and weight of parathyroid adenomas, size was significantly different between patients with negative 99mTc-MIBI/tetrofosmin SPECT/CT and those with positive 99mTc-MIBI/tetrofosmin SPECT/CT (mean size 13.4 ± 7.6 mm vs. 16.9 ± 7.4 mm, respectively; p = 0.042). CONCLUSION: In this prospective study, 18F-fluorocholine PET/CT showed promise as a functional imaging modality, being clearly superior to 99mTc-MIBI/tetrofosmin SPECT/CT, especially in the detection and localization of small parathyroid adenomas in patients with primary hyperparathyroidism. SUVmax was higher in parathyroid adenomas than in hyperplasia. However, further evaluation of this modality is needed.