Quantitative 99mTc-MDP SPECT/CT as an alternative to 18F-NaF PET/CT for objective assessment of osteoblastic bone metastases.

OBJECTIVE: To investigate the correlation between the standardized uptake value (SUV) metrics derived from technetium-99m (99mTc) methylene diphosphonate (MDP) single photon emission computed tomography/computed tomography (SPECT/CT) and fluorine-18 (18F) sodium fluoride (NaF) positron emission tomography (PET)/CT. SUBJECTS AND METHODS: A total of 129 metastatic lesions from 14 patients who underwent both 99mTc-MDP SPECT/CT and 18F-NaF PET/CT within one month were included in the analyses. The lesions with markedly increased uptake were semi-automatically segmented into a volume of interest in both SPECT and PET images by taking the 42% of maximum uptake as a threshold. Maximum, average and minimum SUV (namely, SUVmax, SUVmean and SUVmin) were recorded for each lesion. The strength of correlation was evaluated with Pearson's correlation analysis. RESULTS: The correlation coefficitients for SUVmax, SUVmean and SUVmin derived SPECT and PET images were 0.652, 0.653 and 0.635, respectively (all P<0.001). Lesions with a volume of at least 5cm3 demonstrated a stronger correlation, increasing the correlation coefficients to 0.714, 0.724 and 0.686, respectively (all P<0.001). The strongest correlation was seen in the lesions of the appendicular skeleton, with coefficients for SUVmax, SUVmean and SUVmin being 0.769, 0.791 and 0.761, respectively (all P<0.001). CONCLUSION: The SUV metrics derived from 99mTc-MDP SPECT/CT strongly correlate with 18F-NaF PET, especially for relatively large lesions located in the appendicular skeleton. Technetium-99m-MDP SPECT/CT could potentially be used as an alternative method to 18F-NaF PET/CT for quantitative evaluation and objective follow-up of bone metastases.

Dosimetric approach to 131I ablation therapy for the differentiated thyroid cancer.

OBJECTIVE: The aim of this study is to compare the activity amounts used in the standard activity approach with the activity amounts calculated with the dosimetric method for the ablation of post-operative differentiated thyroid cancer residual tissue. SUBJECTS AND METHODS: Seventeen patients (mean age=47.5±8.4 years) were included in the study. Time-activity curves were created by measuring iodine-131 (131I) uptake values of residual tissue at 4th, 24th, 48th and 96th hours following oral administration of 131I. In a dosimetric approach, activity amounts exposing 300Gy to residual tissue were calculated using medicalinternal radiation dose (MIRD) formulation. RESULTS: Dosimetric calculation could not be made in 3 patients because there was not enough radioactive iodine uptake (RAIU) at the neck to calculate the radioactive iodine treatment (RAIT) dose. The lowest and highest activity amounts determined by dosimetric calculations were 259MBq and 10860MBq, respectively. Dose amounts for the proposed treatment were decreased in 8 and increased in 6 patients compared to the standard activity approach. Cumulative activity (CA) and total cumulative activity (TCA) levels were found to be high in 1 patient who could not achieve adequate ablation. CONCLUSION: We recommend the dosimetric approach for ablation of residual postoperative thyroid tissue to find patients with high levels of CA and TCA levels to consider higher activity doses compared to risk stratification assessment.

Effects of chronic sleep deprivation on upper respiratory tract mucosal histology and mucociliary clearance on rats.

In this study, we aimed to investigate the effects of chronic sleep deprivation on mucociliary clearance, which is the primary defence mechanism of the upper airway tract and nasal mucosal histology. Forty-two Wistar Albino rats (250-300 g), 8 or 12 weeks old, were randomly assigned into three groups as follows. The first sleep-deprivation group consisted of 14 rats (A), another 14 of them were assigned to platform group (B), and the remaining 14 were included to the home cage control group (C). For the two deprivation groups (A and B), the modified multiple platform method (MMPM) was used to induce sleep deprivation for 21 days. Tc-99m MAA rhinoscintigraphy was performed to assess mucociliary clearance and the nasal histopathological changes of the sacrificed rats were also examined. Mucociliary clearance was significantly higher in sleep deprivation (A) and deprivation control (B) groups than the control group (C) (p = .037). The ratio of columnar ciliary was significantly higher in group A and B than in the control group (p = .003). The transitional epithelial ratio in groups A and B was also significantly increased compared with group C (p = .04). The control group's squamous epithelial ratio was increased compared to the sleep-deprived groups (p = .003). There was a significantly increased inflammatory response in the ciliated columnar epithelium in groups A and B compared to group C (p = .02). For the first time in the literature, we demonstrated that chronic sleep deprivation has caused a significant increase in mucociliary clearance speed and in the number of ciliary cells.

Comparison of staging systems in gastric carcinoma.

AIM: Gastric carcinoma is one of the most frequent cancers and leading causes of cancer-related death worldwide. Treatment strategies are planned according to the Tumour-Node-Metastasis (TNM) stage of the disease. However, the prognosis varies substantially even within the same stage. Prognostic nomograms were designed to overcome this diversity. In this study, staging systems and prognostic tools are compared in the context of their ability to predict patients' prognosis. METHODS: Records of 391 patients operated for gastric cancer from January 2006 to September 2013 were analysed retrospectively. TNM staging system, Metastatic lymph node ratio (LNR), Kattan Prognostic Tool and Prognostic Tool of Italian Research Group on Gastric Cancer (GIRCG) were compared with the patients' survival times by their concordance indices and correlation coefficients. RESULTS: A total of 343 patients were included in the study. Concordance indices of the compared staging systems were 0.678 for TNM, 0.601 for GIRCG scale, 0.646 for LNR stage and 0.680 for Kattan scale. Pearson correlation coefficients were 0.404 for TNM staging, 0.314 for GIRCG scale, 0.304 for LNR stage and -0.406 for Kattan scale. Spearman correlation coefficients were 0.383, 0.311, 0.310 and -0.400 respectively. CONCLUSION: Based on these results, Kattan prognostic scale was found to be the most accurate system for predicting mortality. This was followed by TNM staging system.

Use of dose-volume histograms for metabolic response prediction in hepatocellular carcinoma patients undergoing transarterial radioembolization with Y-90 resin microspheres.

INTRODUCTION: Voxel-based dosimetry offers improved outcomes in the treatment of hepatocellular carcinoma (HCC) with transarterial radioembolization (TARE) using glass microspheres. However, the adaptation of voxel-based dosimetry to resin-based microspheres has been poorly studied, and the prognostic relevance of heterogeneous dose distribution remains unclear. This study aims to explore the use of dose-volume histograms for resin microspheres and to determine thresholds for objective metabolic response in HCC patients treated with resin-based TARE. METHODS: We retrospectively reviewed HCC patients who underwent TARE with Y-90-loaded resin microspheres in our institution between January 2021 and December 2022. Voxel-based dosimetry was performed on post-treatment Y-90 PET/CT images to extract parameters including mean dose absorbed by the tumor (mTD), the percentage of the targeted tumor volume (pTV), and the minimum doses absorbed by consecutive percentages within the tumor volume (D10, D25, D50, D75, D90). Assessment of metabolic response was done according to PERCIST criteria with F-18 FDG PET/CT imaging at 8-12 weeks after the treatment. RESULTS: This study included 35 lesions targeted with 22 TARE sessions in 19 patients (15 males, 4 females, mean age 60 ± 13 years). Objective metabolic response was achieved in 43% of the lesions (n = 15). Responsive lesions had significantly higher mTD, pTV, and D25-D90 values (all p < 0.05). Optimal cut-off values for mTD, pTV, and D50 were 94.6 Gy (sensitivity 73%, specificity 70%, AUC 0.72), 94% (sensitivity 73%, specificity 55%, AUC 0.64), and 91 Gy (sensitivity 80%, specificity 80%, AUC 0.80), respectively. CONCLUSION: Parameters derived from dose-volume histograms could offer valuable insights for predicting objective metabolic response in HCC patients treated with resin-based TARE. If verified with larger prospective cohorts, these parameters could enhance the precision of dose distribution and potentially optimize treatment outcomes.

Incidental Spleen Cyst Mimicking Thyroid Carcinoma Metastasis: False-positive Uptake on Radioiodine Whole Body Scan.

In differentiated thyroid cancer, radioiodine therapy and whole body scans (WBS) are integral part of disease management. We present the case of a 33-year-old woman with multifocal thyroid carcinoma who was treated with radioiodine. Post-treatment WBS scintigraphy showed focal increased I-131 uptake in the spleen, although stimulated thyroglobulin level was not suggestive of distant metastasis. Dynamic magnetic resonance imaging performed later revealed that the finding was an incidental splenic cyst. Radioiodine uptake is not specific to the thyroid tissue. Benign pathologies showing increased radioiodine uptake should be considered in cases with splenic radioiodine accumulation in WBSs.

The variation of quantitative parameters and Deauville scores with different reconstruction algorithms in FDG PET/CT imaging of lymphoma patients.

INTRODUCTION AND OBJECTIVES: 18F-FDG PET with the Deauville score (DS) is a unique semiquantitative method for lymphoma. However, type of standard uptake values (max, mean, and peak) reconstruction algorithms could affect DS. We compared the Bayesian Penalized Likelihood reconstruction algorithm (BPL) with Ordered Subsets Expectation Maximization (OSEM) on quantitative parameters and DS in lymphoma. We investigated the effect of the size of the lymph node on quantitative variation. PATIENTS AND METHODS: Raw PET data of 255 lymphoma patients were reconstructed separately with Q.Clear (GE Healthcare), a BPL, and SharpIR (GE Healthcare), an OSEM algorithm. In both images, each patient's liver, mediastinal blood pool, and SUVs (SUVmax, SUVmean, and SUVpeak) of a total of 487 lesions selected from the patients were performed. DSmax, DSmean, and DSpeak were compared. RESULTS: In our study, DS increased significantly with BPL (p < 0.001), and the DS increased to 4-5 in thirty patients evaluated as 1-2-3 with OSEM. It was found that the quantitative values of the lymph nodes increased statistically with BPL (p < 0.001), and the liver from the reference regions were significantly decreased (p < 0.001). In addition, difference in lymph node was independently associated with size of lesion and was significantly more pronounced in small lesions (p < 0.001). The effects of BPL algorithm were more pronounced in SUVmax than in SUVmean and SUVpeak. DS-mean and DS-peak scores were less changed by BPL than DS-max. CONCLUSION: Different reconstruction algorithms in FDG PET/CT affect the quantitative evaluation. That variation may affect the change in DS in lymphoma patients, thus affecting patient management.

Rheumatology experience with FDG PET / CT in inflammation of unknown origin: a single - centre report for determining factors associated with diagnostic precision.

BACKGROUND / AIM: The use of PET / CT is becoming more common in the elucidation of inflammatory processes in which the underlying cause cannot be determined by conventional examinations. Although PET / CT is an effective method for detecting inflammatory foci, the precise diagnosis may not be obtained in all cases. In addition, considering factors such as radiation exposure and cost, it becomes important to identify patients who can get results with PET / CT. In this study, it was aimed to examine the factors that can predict the differential diagnostic value of PET / CT by retrospectively scanning patients who underwent PET / CT for inflammation of unknown origin (IUO) in rheumatology practice. METHODS: Demographic, clinical and laboratory information of the patients followed up in our clinic and who underwent PET / CT for differential diagnosis were enrolled. Whether they were diagnosed after PET / CT and during the follow - up period, and their diagnoses were examined. RESULTS: A total of 132 patients were included in the study. A previous diagnosis of rheumatic disease was present in 28.8 % of the patients, and a history of malignancy was present in 2.3 % . The patients were divided into three groups: group 1 patients with increased FDG uptake in PET / CT and diagnosis confirmed by PET / CT, group 2 patients with increased FDG uptake in PET / CT but diagnosis was not confirmed, and group 3 patients without increased FDG uptake in PET / CT. Increased FDG uptake in PET / CT was detected in 73 % of the patients. While PET / CT helped the diagnosis in 47 (35.6 %) patients (group 1), it did not help the diagnosis in 85 (64.4 %) (groups 2 and 3). Thirty - one (65.9 %) of the diagnosed patients were diagnosed with a rheumatologic disease. When the 3 groups were compared, male gender, advanced age, CRP levels, presence of constitutional symptoms, SUVmax values and number of different organs with increased FDG uptake were higher in Group 1. Sixty - six percent and 74 % of the patients in groups 2 and 3 were not diagnosed during the follow - up period. No patient in group 3 was diagnosed with malignancy during follow - up. CONCLUSION: PET / CT has high diagnostic value when combined with clinical and laboratory data in the diagnosis of IUO. Our study revealed that various factors can affect the diagnostic value of PET / CT. Similar to the literature, the statistically significant difference in CRP levels shows that patients with high CRP levels are more likely to be diagnosed with an aetiology in PET / CT. Although detection of involvement in PET / CT is not always diagnostic, there was an important finding that no malignancy was detected in the follow - up in any patient without PET / CT involvement. Key points • PET / CT is an effective method for detecting inflammatory foci. • PET / CT has proven to be effective in the diagnosis of rheumatological diseases, the extent of disease and the evaluation of response to treatment. • Indications for the use of PET / CT in the field of rheumatology and the associated factors and clinical features supporting the diagnosis with PET / CT are still to be fully clarified. • In routine practice, with PET / CT, both delays in diagnosis and examinations performed during diagnosis and the cost can be reduced.

Stereotactic body radioablation therapy as an immediate and early term antiarrhythmic palliative therapeutic choice in patients with refractory ventricular tachycardia.

BACKGROUND: Stereotactic body radioablation therapy (SBRT) has recently been introduced with the ability to provide ablative energy noninvasively to arrhythmogenic substrate while reducing damage to normal cardiac tissue nearby and minimizing patients' procedural risk. There is still debate regarding whether SBRT has a predominant effect in the early or late period after the procedure. We sought to assess the time course of SBRT's efficacy as well as the value of using a blanking period following a SBRT session. METHODS: Eight patients (mean age 58 ± 14 years) underwent eight SBRT sessions for refractory ventricular tachycardia (VT). SBRT was given using a linear accelerator device with a total dose of 25 Gy to the targeted area. RESULTS: During a median follow-up of 8 months, all patients demonstrated VT recurrences; however, implantable cardioverter-defibrillator (ICD) and anti-tachycardia pacing therapies were significantly reduced with SBRT (8.46 to 0.83/per month, p = 0.047; 18.50 to 3.29/per month, p = 0.036, respectively). While analyzing the temporal SBRT outcomes, the 2 weeks to 3 months period demonstrated the most favorable outcomes. After 6 months, one patient was ICD therapy-free and the remaining patients demonstrated VT episodes. CONCLUSIONS: Our findings showed that the SBRT was associated with a marked reduction in the burden of VT and ICD interventions especially during first 3 months. Although SBRT does not seem to succeed complete termination of VT in long-term period, our findings support the strategy that SBRT can be utilized for immediate antiarrhythmic palliation in critically ill patients with otherwise untreatable refractory VT and electrical storm.

The Role of Histogram-Based Textural Analysis of 18F-FDG PET/CT in Evaluating Tumor Heterogeneity and Predicting the Prognosis of Invasive Lung Adenocarcinoma.

OBJECTIVES: This study aimed to investigate the contributory role of histogram-based textural features (HBTFs) extracted from 18fluorinefluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in tumoral heterogeneity (TH) evaluation and invasive lung adenocarcinoma (ILA) prognosis prediction. METHODS: This retrospective study analyzed the data of 72 patients with ILA who underwent 18F-FDG PET/CT followed by surgical resection. The maximum standardized uptake value (SUVmax), metabolic tumor volume, and total lesion glycolysis values were calculated for each tumor. Additionally, HBTFs were extracted from 18F-FDG PET/CT images using the software program. ILA was classified into the following five histopathological subtypes according to the predominant pattern: Lepidic adenocarcinoma (LA), acinar adenocarcinoma, papillary adenocarcinoma, solid adenocarcinoma (SA), and micropapillary adenocarcinoma (MA). Differences between 18F-FDG PET/CT parameters and histopathological subtypes were evaluated using non-parametric tests. The study endpoints include overall survival (OS) and progression-free survival (PFS). The prognostic values of clinicopathological factors and 18F-FDG PET/CT parameters were evaluated using the Cox regression analyses. RESULTS: The median SUVmax and entropy values were significantly higher in SA-MA, whereas lower in LA. The median energy-uniformity value of the LA was significantly higher than the others. Among all parameters, only skewness and kurtosis were significantly associated with lymph node involvement status. The median values for follow-up time, PFS, and OS were 31.26, 16.07, and 20.87 months, respectively. The univariate Cox regression analysis showed that lymph node involvement was the only significant predictor for PFS. The multivariate Cox regression analysis revealed that higher SUVmax (≥11.69) and advanced stage (IIB-IIIA) were significantly associated with poorer OS [hazard ratio (HR): 3.580, p=0.024 and HR: 7.608, p=0.007, respectively]. CONCLUSION: HBTFs were tightly associated with clinicopathological factors causing TH. Among the 18F-FDG PET/CT parameters, only skewness and kurtosis were associated with lymph node involvement, whereas SUVmax was the only independent predictor of OS. TH measurement with HBTFs may contribute to conventional metabolic parameters in guiding precision medicine for ILA.

The impact of 18F-fluorodeoxyglucose PET/computed tomography on clinical staging in bladder cancer.

AIM: To determine the impact of 18F-FDG PET/computed tomography (CT) on clinical staging in bladder cancer with comparison to conventional CT and MRI. METHODS: A total of 142 patients who underwent 18F-FDG PET/CT imaging with a diagnosis of bladder cancer between 1 June 2019 and 31 December 2020 were screened retrospectively. Seventy patients who underwent diagnostic CT or MRI within 2 months before or after PET/CT were included in the study. The N and M stages determined by CT, MRI and PET/CT according to the eighth version of the TNM staging system were recorded. T-test was used to determine the levels of significant difference, and univariate logistic regression analysis was used to evaluate the impact of the T stage on nodal up-staging. RESULTS: According to the PET/CT, the N stage increased in 19 patients (27.14%) and decreased in seven patients (10%). Likewise, the M stage increased in 16 patients (22.86%) and decreased in seven patients (10%). The N stage determined by PET/CT was confirmed by pathologic examination in all cases in which the two modalities were inconsistent. In muscle-invasive cases, the rate of increase in the N stage after PET/CT (36.95%) was found to be significantly higher than in that of cases without invasion (8.33%) (P = 0.011). Increasing T stage was associated with an increase in the N stage after PET/CT (odds ratio: 2.33, 95% confidence interval: 1.02-5.28, P = 0.042). CONCLUSION: 18F-FDG PET/CT can potentially change the clinical stage determined by CT and MRI when used for staging in bladder cancer, and can lead to nodal up-staging particularly in cases with muscle-invasive bladder cancer.

Association of 18F-FDG PET/CT textural features with immunohistochemical characteristics in invasive ductal breast cancer.

OBJECTiVES: This study investigates whether textural features (TFs) extracted from 18F-FDG positron emission tomography/computed tomography (PET/CT) are associated with immunohistochemical characteristics (IHCs) of invasive ductal breast carcinoma (IDBC). MATERIALS AND METHODS: The relationship of TFs with IHCs [estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER-2), Ki-67 proliferation index, and histological grades] from solely excised primary tumors were evaluated for a more accurate assessment. Therefore patients with early-stage IDBC who underwent pre-operative 18F-FDG PET/CT scan for staging were included in this retrospective study. The clinical staging was performed according to the 8th edition of the American Joint Committee on Cancer. Maximum standardized uptake value (SUVmax) and 37TFs of the primary tumor were extracted from 18F-FDG PET/CT. Spearman's rank correlation test was used to evaluate the correlation between TFs and SUVmax. Receiver operating characteristic curves were generated to define the diagnostic performance of each parameter. Among these parameters, those with the highest diagnostic performance were included in the multivariate logistic regression model to identify the independent predictors of histopathological characteristics. RESULTS: A total of 124 patients were included. Histogram-uniformity, grey-level co-occurrence matrix (GLCM), GLCM-energy, and GLCM-homogeneity showed a strong negative correlation with SUVmax, while grey-level run-length matrix (GLRLM), GLRLM-SRHGE, grey-level zone length matrix (GLZLM), GLZLM-HGZE, GLRLM-HGRE, GLCM-entropy, GLCM-contrast, histogram-entropy, and GLCM-dissimilarity showed a strong positive correlation. Some of the TFs were independently associated with ER-negativity, PR-negativity, HER-2-positivity, and increased Ki-67 proliferation index (GLCM-contrast, GLZLM-GLNU, histogram-uniformity, and shape-sphericity respectively). While SUVmax had an independent association with high-grade and triple-negativity, GLZLM-SZLGE, a high-order TF that shows the distribution of the short homogeneous zones with low grey-levels, had an independent association with axillary lymph node metastasis. CONCLUSIONS: ER-negative, PR-negative, HER-2-positive, triple-negative, high-grade, highly proliferative, and high-stage tumors were found to be more glycolytic and metabolically heterogeneous. These findings suggest that the use of TFs in addition to SUVmax may improve the prognostic value of 18F-FDG PET/CT in IDBC, as certain TFs were independently associated with many IHCs and predicted axillary lymph node involvement.

The Radiation Dose Absorbed by Healthy Parenchyma Is a Predictor for the Rate of Contralateral Hypertrophy After Unilobar Radioembolization of the Right Liver.

Purpose: To investigate the predictors of contralateral hypertrophy in patients treated with unilobar transarterial radioembolization (TARE) with yttrium-90-loaded resin microspheres due to unresectable right-liver tumors. Methods: Patients who underwent right unilobar TARE with resin microspheres between May 2019 and September 2021 were screened retrospectively. Contralateral hypertrophy was evaluated by calculating the kinetic growth rate (KGR) in 8-10 weeks after TARE. The predictors of increased KGR were determined with linear regression analysis. Results: A total of 24 patients (16 with primary and 8 with metastatic liver tumors) were included in the study. After right unilobar TARE, mean volume of the left lobe increased from 368.26 to 436.16 mL, while the mean volume of the right lobe decreased from 1576.22 to 1477.89 mL. The median KGR of the left lobe was 0.28% per week. The radiation dose absorbed by the healthy parenchyma of the right lobe was significantly higher in patients with increased KGR (31.62 vs. 18.78 Gy, p = 0.037). Linear regression analysis showed that the dose absorbed by healthy parenchyma was significantly associated with increased KGR (b = 0.014, p = 0.043). Conclusion: Patients who received right unilobar TARE for liver malignancies could develop a substantial contralateral hypertrophy, and the radiation dose absorbed by the healthy parenchyma of the right lobe was significantly associated with increased KGR in the left lobe. TARE could have a role for inducing contralateral hypertrophy as it offers the advantage of concurrent local tumor control along with its hypertrophic effect.

Development and validation of a nomogram for predicting the likelihood of metastasis in prostate cancer patients undergoing Ga-68 PSMA PET/CT due to biochemical recurrence.

OBJECTIVE: To develop a nomogram based on commonly used clinical data for predicting the likelihood of metastasis in gallium-68 prostate-specific membrane antigen PET/computed tomography (Ga-68 PSMA PET/CT) scans of prostate cancer patients with confirmed biochemical recurrence (BCR). METHODS: One-hundred thirty-five ( n = 135) patients who underwent Ga-68 PSMA PET/CT due to BCR were included in the study. Predictors of metastasis in Ga-68 PSMA PET/CT were determined with multivariable logistic regression analysis. Coefficients derived from the regression model were used to develop a prediction nomogram. The performance of the prediction model was evaluated with receiver operating characteristic analysis. Internal validation was performed with 50 bootstrap resamples, and the nomogram's clinical benefit was assessed with decision curve analysis. RESULTS: Multivariable logistic regression analysis revealed that ISUP group, prostate-specific antigen (PSA) before PET and PSA doubling time were independent predictors of metastasis in Ga-68 PSMA PET/CT. A prediction nomogram was developed according to this model [the area under curve: 0.866; 95% confidence interval (CI), 0.788-0.944]. The best cutoff value of the nomogram-derived likelihood for predicting metastasis was 60%, with a bootstrap-corrected accuracy of 78.8%. An online version of the nomogram was implemented on pro-gram.nzm.co ( https://pro-gram.nzm.co ). CONCLUSION: The proposed nomogram provides a practical approach for predicting the likelihood of imaging-based metastasis according to Ga-68 PSMA PET/CT in patients with BCR, with results ≥60% being the most accurate cutoff for referring patients to Ga-68 PSMA PET/CT. If validated in a larger cohort, this tool can serve as a guide for the appropriate use of Ga-68 PSMA PET/CT.

Tc-99m pyrophosphate scintigraphy for cardiac amyloidosis: concordance between planar and SPECT/CT imaging.

The imaging protocol and the optimal cut-off points for quantitative assessment of technetium-99m pyrophosphate (Tc-99m PYP) cardiac amyloidosis scintigraphy remain controversial. The aim of this study was to evaluate the concordance between planar and SPECT images, and to investigate the contribution of SPECT/CT to diagnostic precision. All patients referred to our department for Tc-99m PYP cardiac imaging between April 2019 and April 2022 were included in the study. Heart-to-contralateral lung (H/CL) ratios were calculated from anterior planar images at both 1- and 3 h, and visual grading was done in SPECT/CT images at both time points. A total of 141 patients were included in the study (median age 59 years, 54% female). There was a strong positive correlation between H/CL ratios calculated at 1- and 3 h (Pearson's ρ = 0.842, p < 0.001). The highest level of concordance between planar and SPECT/CT images was achieved at a H/CL cut-off point of 1.5 for 1-h images, and 1.4 for 3-h images. SPECT/CT imaging contributed to diagnostic precision in both 1- and 3-h images by reducing the rate of equivocal results from 83% (n = 117) to 25% (n = 35), and from 77% (n = 108) to 27% (n = 38), respectively. Our findings have three implications: (1) planar imaging at both 1- and 3 h could be redundant, (2) a lower H/CL cut-off point for 3-h planar images could improve concordance between planar and SPECT imaging, and (3) SPECT/CT in both 1- and 3 h could improve the diagnostic precision by offering markedly reduced equivocal results.

Association of entirely claims-based frailty indices with long-term outcomes in patients with acute myocardial infarction, heart failure, or pneumonia: a nationwide cohort study in Turkey.

BACKGROUND: Several countries have increasingly focused on improving care for acute myocardial infarction (AMI), heart failure (HF), and pneumonia to reduce their readmissions and mortality rates. Frailty is becoming increasingly important to accurately predict healthcare utilization for the aging population. The preferred method for the measurement of frailty remains unclear, and current risk-adjustment models do not account for frailty. We sought to compare commonly used frailty indices in terms of the ability to predict clinical adverse outcomes in AMI, HF, and pneumonia patients. METHODS: A nationwide cohort study included AMI, HF, and pneumonia with 65 years and older patients in the Turkey between January 1 and December 31, 2018. The primary predictor of interest was frailty. We used two claims-based frailty indices (Johns Hopkins Claims-Based Frailty Index and Hospital Frailty Risk Score) to assess frailty. The main outcome was all-cause long-term mortality up to 3 years. Time to death was calculated as the time period between the date of first admission and the date of death. Patients were censored as of September 30, 2020, which marked the end of the follow-up period. FINDINGS: Of the 200,948 patients, 35,096 (17.5%) had AMI, 62,403 (31.1%) had HF, and 103,449 (51.5%) had pneumonia. Johns Hopkins Claims-Based Frailty Index (c-statistics for long-term mortality: 0.68 in AMI, 0.61 in HF, 0.64 in pneumonia) was better compared to Hospital Frailty Risk Score (c-statistics for long-term mortality: AMI=0.62, HF=0.58, pneumonia=0.62) (DeLong p<0.001 in all). INTERPRETATION: Readmission and mortality rates after AMI, HF, and pneumonia gradually increases with increasing frailty score. While the Hospital Frailty Risk Score had a better discrimination for predicting readmissions, Johns Hopkins Claims-Based Frailty Index had a better discrimination for predicting mortality. These findings should be taken into account for a better evaluation of hospital performance. FUNDING: This study was supported by funding from The Scientific and Technological Research Council of Turkey (grant 120S422, HK).

Baseline 18F-FDG PET textural features as predictors of response to chemotherapy in diffuse large B-cell lymphoma.

PURPOSE: We sought to investigate the performance of radiomics analysis on baseline 18F-FDG PET/CT for predicting response to first-line chemotherapy in diffuse large B-cell lymphoma (DLBCL). MATERIAL AND METHODS: Forty-five patients who received first-line rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) chemotherapy for DLBCL were included in the study. Radiomics features and standard uptake value (SUV)-based measurements were extracted from baseline PET images for a total of 147 lesions. The selection of the most relevant features was made using the recursive feature elimination algorithm. A machine-learning model was trained using the logistic regression classifier with cross-validation to predict treatment response. The independent predictors of incomplete response were evaluated with multivariable regression analysis. RESULTS: A total of 14 textural features were selected by the recursive elimination algorithm, achieving a feature-to-lesion ratio of 1:10. The accuracy and area under the receiver operating characteristic curve of the model for predicting incomplete response were 0.87 and 0.81, respectively. Multivariable analysis revealed that SUVmax and gray level co-occurrence matrix dissimilarity were independent predictors of lesions with incomplete response to first-line R-CHOP chemotherapy. CONCLUSION: Increased textural heterogeneity in baseline PET images was found to be associated with incomplete response in DLBCL.

Assessment of volumetric parameters derived from 68Ga-PSMA PET/CT in prostate cancer patients with biochemical recurrence: an institutional experience.

OBJECTIVE: The aim of this study was to evaluate the relationship between volumetric parameters calculated using semiautomatic quantification of lesions detected in 68Ga-labeled prostate-specific membrane antigen PET-computed tomography (68Ga-PSMA PET/CT) and clinical characteristics in prostate cancer (PCa) patients with biochemical recurrence. METHODS: A total of 85 consecutive PCa patients with biochemical recurrence who underwent 68Ga-PSMA PET/CT at our institution from January 2019 to March 2020 were retrospectively assessed. 68Ga-PSMA PET/CT-derived volumetric parameters, including whole-body PSMA tumor volume (wbPSMA-TV) and whole-body total lesion PSMA (wbTL-PSMA), as well as the established maximum and mean standardized uptake value (SUVmax and SUVmean), were calculated for each patient. All PET-derived parameters were analyzed for correlation with prostate-specific antigen (PSA) levels and for association with Gleason scores. RESULTS: Eighty-five patients with a mean age of 68.9 ± 7.8 years (range, 47-83 years) and a mean PSA level of 40.9 ± 92.1 ng/ml (range, 0.2-533.2 ng/ml) were analyzed. Volumetric parameters, that is, wbPSMA-TV and wbTL-PSMA, demonstrated a statistically significant correlation with PSA levels (r = 0.403 and r = 0.556, respectively, all at P < 0.001) and only the means of wbTL-PSMA were significantly different between the Gleason score groups (P < 0.05). CONCLUSIONS: The results of our study indicate that 68Ga-PSMA PET/CT might be a valuable tool for the detection and follow-up of recurrence in PCa patients. 68Ga-PSMA PET/CT-derived quantitative volumetric parameters demonstrated a highly significant correlation with changes in PSA levels. Larger prospective studies are needed to help reveal the full potential of parameters such as PSMA-TV and TL-PSMA derived from PET imaging with 68Ga-PSMA.

Use of Stereotactic Radioablation Therapy as a Bailout Therapy for Refractory Ventricular Tachycardia in a Patient with a No-entry Left Ventricle.

In patients with mechanical aortic and mitral valves and left ventricular (LV) tachycardia (VT), catheter ablation is technically challenging due to the limited access to the LV. Promising new alternatives to radiofrequency ablation include pulsed-field electroporation, percutaneous or surgical sympathetic neuromodulation, and noninvasive stereotactic radioablation therapy (SBRT). We herein describe the effect of SBRT as a bailout therapy on the management of a challenging VT case in the presence of double left-sided mechanical valves.