99m Technetium-pyrophosphate bone scan: A potential biomarker for the burden of transthyretin amyloidosis in skeletal muscle: A preliminary study.

INTRODUCTION/AIMS: Transthyretin amyloidosis (ATTR) proteins can infiltrate skeletal muscle and infrequently cause a myopathy. 99m Technetium-pyrophosphate (99m Tc-PYP) is a validated biomarker for cardiac involvement in variant and wild-type ATTR (ATTRv and ATTRwt, respectively). The aim of this study was to test the hypothesis that 99m Tc-PYP is a biomarker for muscle burden of ATTR. METHODS: Radioisotope uptake in the deltoid muscles of patients with ATTR was compared to uptake in control subjects without amyloidosis in a retrospective study. 99m Tc-PYP scans were evaluated in 11 patients with ATTR (7 ATTRv, 4 ATTRwt) and 14 control subjects. Mean count (MC) values were measured in circular regions of interest (ROIs) 2.5-3.8 cm2 in area. Tracer uptake was quantified in the heart, contralateral chest (CC), and deltoid muscles. RESULTS: Tracer uptake was significantly higher over the deltoids and heart but not the CC, in patients with ATTR than in control subjects. MC values were 120.1 ± 43.7 (mean ± SD) in ATTR patients and 78.9 ± 20.4 in control subjects over the heart (p = 0.005), 73.3± 21.0 and 63.5 ± 14.4 over CC (p = 0.09), and 37.0 ± 11.7 and 26.0 ± 7.1 averaged over both deltoid muscles (p = 0.014). DISCUSSION: 99m Tc-PYP is a potential biomarker for ATTR amyloid burden in skeletal muscle.

Developing and validating a novel metabolic tumor volume risk stratification system for supplementing non-small cell lung cancer staging.

PURPOSE: We hypothesized that whole-body metabolic tumor volume (MTVwb) could be used to supplement non-small cell lung cancer (NSCLC) staging due to its independent prognostic value. The goal of this study was to develop and validate a novel MTVwb risk stratification system to supplement NSCLC staging. METHODS: We performed an IRB-approved retrospective review of 935 patients with NSCLC and FDG-avid tumor divided into modeling and validation cohorts based on the type of PET/CT scanner used for imaging. In addition, sensitivity analysis was conducted by dividing the patient population into two randomized cohorts. Cox regression and Kaplan-Meier survival analyses were performed to determine the prognostic value of the MTVwb risk stratification system. RESULTS: The cut-off values (10.0, 53.4 and 155.0 mL) between the MTVwb quartiles of the modeling cohort were applied to both the modeling and validation cohorts to determine each patient's MTVwb risk stratum. The survival analyses showed that a lower MTVwb risk stratum was associated with better overall survival (all p < 0.01), independent of TNM stage together with other clinical prognostic factors, and the discriminatory power of the MTVwb risk stratification system, as measured by Gönen and Heller's concordance index, was not significantly different from that of TNM stage in both cohorts. Also, the prognostic value of the MTVwb risk stratum was robust in the two randomized cohorts. The discordance rate between the MTVwb risk stratum and TNM stage or substage was 45.1% in the modeling cohort and 50.3% in the validation cohort. CONCLUSION: This study developed and validated a novel MTVwb risk stratification system, which has prognostic value independent of the TNM stage and other clinical prognostic factors in NSCLC, suggesting that it could be used for further NSCLC pretreatment assessment and for refining treatment decisions in individual patients.

Computer-assisted Curie scoring for metaiodobenzylguanidine (MIBG) scans in patients with neuroblastoma.

BACKGROUND: Radiolabeled metaiodobenzylguanidine (MIBG) is sensitive and specific for detecting neuroblastoma. The extent of MIBG-avid disease is assessed using Curie scores. Although Curie scoring is prognostic in patients with high-risk neuroblastoma, there is no standardized method to assess the response of specific sites of disease over time. The goal of this study was to develop approaches for Curie scoring to facilitate the calculation of scores and comparison of specific sites on serial scans. PROCEDURE: We designed three semiautomated methods for determining Curie scores, each with increasing degrees of computer assistance. Method A was based on visual assessment and tallying of MIBG-avid lesions. For method B, scores were tabulated from a schematic that associated anatomic regions to MIBG-positive lesions. For method C, an anatomic mesh was used to mark MIBG-positive lesions with automatic assignment and tallying of scores. Five imaging physicians experienced in MIBG interpretation scored 38 scans using each method, and the feasibility and utility of the methods were assessed using surveys. RESULTS: There was good reliability between methods and observers. The user-interface methods required 57 to 110 seconds longer than the visual method. Imaging physicians indicated that it was useful that methods B and C enabled tracking of lesions. Imaging physicians preferred method B to method C because of its efficiency. CONCLUSIONS: We demonstrate the feasibility of semiautomated approaches for Curie score calculation. Although more time was needed for strategies B and C, the ability to track and document individual MIBG-positive lesions over time is a strength of these methods.

Relationship between Overall Survival of Patients with Non-Small Cell Lung Cancer and Whole-Body Metabolic Tumor Burden Seen on Postsurgical Fluorodeoxyglucose PET Images.

PURPOSE: To test the hypothesis that whole-body metabolic tumor burden (MTBWB) on postsurgical fluorodeoxyglucose (FDG) positron emission tomographic (PET)/computed tomographic (CT) images in patients with non-small cell lung cancer (NSCLC) is associated with their overall survival (OS). MATERIALS AND METHODS: The institutional review board approved this study and waived the requirement for obtaining informed consent. One hundred forty-two patients with NSCLC (69 men, 73 women; median age, 67.7 years) who underwent postsurgical FDG PET/CT were retrospectively reviewed. The whole-body metabolic tumor volume (MTVWB), whole-body total lesion glycolysis (TLGWB), and whole-body maximum standardized uptake value (SUVWBmax) were measured. OS served as the primary end point of the study. Kaplan-Meier curves and Cox regression were used to assess the association between PET/CT markers and OS. RESULTS: The interobserver variability was low, as demonstrated with intraclass correlation coefficients higher than 0.94 for SUVWBmax, MTVWB, and TLGWB. When compared with those with negative postsurgical FDG PET/CT findings, a significant decrease of OS was found in patients with the presence of FDG-avid tumor on the basis of both a log-rank test (P = .001) and a univariate Cox model (hazard ratio = 2.805, P = .001). In patients with FDG-avid tumor, there was a significant association between OS and ln MTVWB (P < .001), ln TLGWB (P < .001), and ln SUVWBmax (P < .010) in either univariate or multivariate analysis, after adjusting for patient age, sex, TNM restage, and therapy after postsurgical PET/CT studies. The OS differences between the groups dichotomized by the median value of MTVWB (11.54 mL, P = .004), TLGWB (32.38 mL, P < .001), or SUVWBmax (4.93, P = .023) were significant. CONCLUSION: MTBWB and tumor maximum standardized uptake at postsurgical FDG PET/CT are related to the patient's OS in NSCLC, independent of age, sex, TNM restaging, and therapy after postsurgical PET/CT studies.

Evaluation of the gallbladder and cystic duct patency with gadoxetate disodium enhanced MR cholangiography: prospective comparison of patients with normal gallbladder function and acute cholecystitis.

BACKGROUND: Using hepatocyte-specific magnetic resonance imaging (MRI) contrast agents such as gadoxetate disodium, MRI can provide functional information regarding the patency of the cystic duct similar to hepatobiliary scintigraphy in addition to anatomic images. PURPOSE: To describe the gadoxetate disodium enhanced MR cholangiography (GDE-MRC) findings in patients with acute cholecystitis and to compare them with findings in patients without acute cholecystitis and with normal hepatobiliary scintigraphy. MATERIAL AND METHODS: This study was HIPAA compliant and institutional review board approved. Twenty-three patients (n = 14 diagnosed with acute calculous cholecystitis based on ultrasound [US] or computed tomography [CT]; n = 9 controls with normal hepatobiliary scintigraphy) were prospectively enrolled. All patients underwent GDE-MRC within 2 days of the US, CT, or hepatobiliary scintigraphy. GDE-MRC included axial gradient echo T1-weighted images before and 3, 10, 20, 30, and 60 min after injection of 10 mL of gadoxetate disodium. If excretion of contrast into the gallbladder was not noted at 60 min, intravenous morphine was administered (0.04 mg/kg) and images were acquired 30 min later. RESULTS: In all nine controls, gadoxetate disodium was excreted into the gallbladder within 60 min (7/9 in <30 min). Twelve out of 14 patients with acute cholecystitis completed the study. Six out of 12 (50%) patients demonstrated contrast in their gallbladder within 1 h of administration similar to the control group (2/6 in <30 min). In the remaining 6/12 patients, contrast was not present in the gallbladder within 1 h from injection. Following morphine augmentation, contrast was subsequently noted in the gallbladder in 2/6 patients. CONCLUSION: GDE-MRC can assess the patency of the cystic duct. Delayed (>60 min) or lack of filling of the gallbladder during GDE-MRC supports the diagnosis of acute cholecystitis. However, filling of the gallbladder with contrast in <60 min does not exclude the diagnosis of acute calculous cholecystitis.

Residual Pulmonary Vascular Obstruction Following Mechanical Thrombectomy for Submassive Pulmonary Embolism: A Single-Center Analysis.

Background: Residual pulmonary vascular obstruction (RPVO) following pulmonary embolism (PE) is associated with residual dyspnea, recurrent venous thromboembolism, and chronic thromboembolic pulmonary hypertension. Historically, acute PE treated with anticoagulation alone results in high rates of significant RPVO. Contemporary treatment of submassive PE often involves catheter-based interventions, including mechanical thrombectomy (MT), although their relation to RPVO is not characterized. In this study, we aimed to evaluate the rate of ≥10% RPVO in patients treated with MT. Methods: Twenty consecutive patients with submassive PE in a single center underwent MT and subsequent planar ventilation/perfusion scintigraphy scan at a median of 4 months after thrombectomy. A quantitative perfusion score was calculated for each planar ventilation/perfusion scintigraphy study to provide a % perfusion defect. Complete hemodynamic data were collected during the procedure and Miller score was calculated using prepulmonary and postpulmonary angiography. Echocardiographic data were collected prior to, 24 to 48 hours after, and 30 days after the procedure. Results: Four of 20 patients (20%) had ≥10% RPVO at a median of 4 months follow-up. Following MT, the mean Miller score decreased from 24.5 ± 2.9 to 15.8 ± 3.3 (P < .001) and mean pulmonary artery pressure decreased from 36.1 ± 4.8 mm Hg to 26.8 ± 5.4 mm Hg (P < .001). Right ventricle-to-left ventricle ratio decreased from 1.44 ± 0.2 to 1.05 ± 0.24 by 24 to 48 hours (P < .001) and 0.85 ± 0.1 at 30 days (P < .001) and right ventricular systolic pressure decreased from 63.2 ± 10 mm Hg to 42.1 ± 9.8 mm Hg at 24 to 48 hours (P < .001) and 31.9 ± 10.4 at 30 days (P < .001). Conclusions: In this prospective study of patients with submassive PE treated with MT, favorable rates of RPVO were noted in comparison to prior studies of anticoagulation alone along with expected acute hemodynamic and echocardiographic improvements. While this study was small in scope, the results suggest the potential for long-term benefits of MT in acute PE in addition to the acute benefits previously described.

Comparison of Measurement and Prognostic Power of SUV Between High-Definition and Standard PET Imaging in Non-Small Cell Lung Cancer Patients.

This study aimed to evaluate the measurement and prognostic ability of the SUVmax of whole-body tumors (SUVmaxwb) in non-small cell lung cancer (NSCLC) patients, comparing high-definition (HD) PET imaging with standard-definition (SD) PET imaging. Methods: The study included 242 consecutive NSCLC patients who underwent baseline 18F-FDG PET/CT from April 2018 to January 2021. Two imaging techniques were used: HD PET (using ordered-subsets expectation maximization with point-spread function modeling and time-of-flight techniques and smaller voxels) and SD PET (with ordered-subsets expectation maximization and time-of-flight techniques). SUVmaxwb was determined by measuring all the tumor lesions in the whole body, and tumor-to-background ratio (TBR) was calculated using the background SUVmean of various body parts. Results: The patient cohort had an average age of 68.3 y, with 59.1% being female. During a median follow-up of 29.6 mo, 83 deaths occurred. SUVmaxwb was significantly higher in HD PET than SD PET, with respective medians of 17.4 and 11.8. The TBR of 1,125 tumoral lesions was also higher in HD PET. Univariate Cox regression analysis showed that SUVmaxwb from both HD and SD PET were significantly associated with overall survival. However, after adjusting for TNM (tumor, node, metastasis) stage, only SUVmaxwb from SD PET remained significantly associated with survival. Conclusion: HD PET imaging in NSCLC patients yields higher SUVmaxwb and TBR, enhancing tumor visibility. Despite this, its prognostic value is less significant than SD PET after adjusting clinical TNM stage. Thus, consideration should be given to using HD PET reconstruction to increase tumor visibility, and SD PET is recommended for NSCLC patient prognostication and therapeutic evaluation, as well as for the classification of lung nodules.

MEN1/DAXX/ATRX mutations enhance progression-free survival in gastroenteropancreatic neuroendocrine tumors treated with peptide receptor radionuclide therapy.

Pre-clinical data suggest that mutations in the MEN1, DAXX, and/or ATRX genes may potentially increase radiation efficacy in cancer cells. Herein, we explore the association between response to peptide receptor radionuclide therapy (PRRT) and those mutations in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs). We analyzed tissue-based next generation sequencing (NGS) assay results and clinicopathologic data from 28 patients with GEP-NETs treated with PRRT. Findings were correlated with progression-free survival (PFS) and objective response rate (ORR). Patients with mutations in MEN1, DAXX, and/or ATRX (n = 13) had a longer median PFS (26.47 vs 12.13 months; P = 0.014) than wild-type (n = 15) patients when adjusted for surgery prior to PRRT, tumor grade, and presence of TP53 mutation. Alterations in MEN1 along with a concurrent mutation in either DAXX or ATRX (n = 6) trended toward longer PFS compared to patients without concurrent mutations (31.53 vs 17.97 months; P = 0.09). ORR was higher in patients with a mutation in MEN1, DAXX, or ATRX (41.67% vs 15.38%). In pancreatic NET patients, these target mutations also showed a longer PFS (28.43 vs 9.83 months; P = 0.04). TP53 alterations showed a shorter PFS than wild-type cases (11.17 vs 20.47 months; P = 0.009). Mutations in MEN1/DAXX/ATRX are associated with improved PFS in patients with GEP-NETs receiving PRRT and might be used as a biomarker for treatment response.

Optimization of Metabolic Tumor Volume as a Prognostic Marker in CAR T-Cell Therapy for Aggressive Large B-cell NHL.

BACKGROUND: CD19-targeted chimeric antigen receptor (CAR) T-cell therapy has become a standard of care in relapsed/refractory (R/R) aggressive large B-cell non-Hodgkin lymphomas (B-NHL) though the majority of recipients do not receive durable disease benefit, prompting the need to better define risk factors for relapse/progression. OBJECTIVES: We performed a single-center, retrospective analysis of patients treated with commercial CAR T-cell therapy to evaluate the impact of tumor burden, as measured by whole-body metabolic tumor volume (MTV) from 18F fluorodeoxyglucose PET imaging, on treatment outcomes. STUDY DESIGN: Sixty-one patients treated with CAR T-cell therapy for R/R B-NHL between May 2016 and November 2021 were included. RESULTS: Using a receiver operating characteristic curve-based MTV optimization cutoff of 450 mL, 1-year progression-free survival (PFS) was 22% for high MTV versus 54% for low MTV (P < .01), and 1-year overall survival (OS) was 37% and 73%, respectively (P = .01). In a subset of 46 patients, residual MTV of less than 106 mL at the day 30 (D30) disease assessment was associated with significantly improved outcomes (1-year OS 85% vs. 13%, P < .01). Incorporation of pretreatment MTV to the International Prognostic Index (IPI) scoring system significantly distinguished 2-year PFS and OS outcomes by 3 risk groups. CONCLUSIONS: Our findings suggest that both pretreatment and D30 MTV are predictive of outcomes among R/R B-NHL patients treated with CAR T-cell therapy. These data indicate that efforts to reduce pretreatment tumor burden may improve longitudinal clinical outcomes. Furthermore, D30 postinfusion MTV quantification may aid clinicians in optimally identifying patients at high-risk for progression, and in whom closer disease monitoring should be considered. MTV also adds prognostic value to patients with high-risk IPI and holds promise for incorporation in novel risk scoring systems which can identify patients prior to CAR T-cell therapy at highest risk of adverse outcomes.

Prognostic value of metabolic tumor burden on 18F-FDG PET in nonsurgical patients with non-small cell lung cancer.

PURPOSE: The objective of this study was to assess the prognostic value of metabolic tumor burden on 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) positron emission tomography (PET)/CT measured with metabolic tumor volume (MTV) and total lesion glycolysis (TLG), independent of Union Internationale Contra la Cancrum (UICC)/American Joint Committee on Cancer (AJCC) tumor, node, and metastasis (TNM) stage, in comparison with that of standardized uptake value (SUV) in nonsurgical patients with non-small cell lung cancer (NSCLC). METHODS: This study retrospectively reviewed 169 consecutive nonsurgical patients (78 men, 91 women, median age of 68 years) with newly diagnosed NSCLC who had pretreatment (18)F-FDG PET/CT scans. The (18)F-FDG PET/CT scans were performed in accordance with National Cancer Institute guidelines. The MTV of whole-body tumor (MTV(WB)), of primary tumor (MTV(T)), of nodal metastases (MTV(N)), and of distant metastases (MTV(M)); the TLG of whole-body tumor (TLG(WB)), of primary tumor (TLG(T)), of nodal metastases (TLG(N)), and of distant metastases (TLG(M)); the SUV(max) of whole-body tumor (SUV(maxWB)), of primary tumor (SUV(maxT)), of nodal metastases (SUV(maxN)), and of distant metastases (SUV(maxM)) as well as the SUV(mean) of whole-body tumor (SUV(meanWB)), of primary tumor (SUV(meanT)), of nodal metastases (SUV(meanN)), and of distant metastases (SUV(meanM)) were measured with the PETedge tool on a MIMvista workstation with manual adjustment. The median follow-up among survivors was 35 months from the PET/CT (range 2-82 months). Statistical methods included Kaplan-Meier curves, Cox regression, and C-statistics. RESULTS: There were a total of 139 deaths during follow-up. Median overall survival (OS) was 10.9 months [95% confidence interval (CI) 9.0-13.2 months]. The MTV was statistically associated with OS. The hazard ratios (HR) for 1 unit increase of ln(MTV(WB)), √(MTV(T)), √(MTV(N)), and √(MTV(M)) before/after adjusting for stage were: 1.47/1.43 (p < 0.001/<0.001), 1.06/1.05 (p < 0.001/<0.001), 1.11/1.10 (p < 0.001/<0.001), and 1.04/1.03 (p = 0.007/0.043), respectively. TLG had statistically significant associations with OS with the HRs for 1 unit increase in ln(TLG(WB)), √(TLG(T)), √(TLG(N)), and √(TLG(M)) before/after adjusting for stage being 1.36/1.33 (p < 0.001/<0.001), 1.02/1.02 (p = 0.001/0.002), 1.05/1.04 (p < 0.001/<0.001), and 1.02/1.02 (p = 0.003/0.024), respectively. The ln(SUV(maxWB)) and √(SUV(maxN)) were statistically associated with OS with the corresponding HRs for a 1 unit increase before/after adjusting for stage being 1.46/1.43 (p = 0.013/0.024) and 1.22/1.16 (p = 0.002/0.040). The √(SUV(meanN)) was statistically associated with OS before and after adjusting for stage with HRs for a 1 unit increase of 1.32 (p < 0.001) and 1.24 (p = 0.015), respectively. The √(SUV(meanM)) and √(SUV(maxM)) were statistically associated with OS before adjusting for stage with HRs for a 1 unit increase of 1.26 (p = 0.017) and 1.18 (p = 0.007), respectively, but not after adjusting for stage (p = 0.127 and 0.056). There was no statistically significant association between OS and √(SUV(maxT)), ln(SUV(meanWB)), or √(SUV(meanT)). There was low interobserver variability among three radiologists with intraclass correlation coefficients (ICC) greater than 0.94 for SUV(maxWB), ln(MTV(WB)), and ln(TLG(WB)). Interobserver variability was higher for SUV(meanWB) with an ICC of 0.806. CONCLUSION: Baseline metabolic tumor burdens at the level of whole-body tumor, primary tumor, nodal metastasis, and distant metastasis as measured with MTV and TLG on FDG PET are prognostic measures independent of clinical stage with low inter-observer variability and may be used to further stratify nonsurgical patients with NSCLC. This study also suggests MTV and TLG are better prognostic measures than SUV(max) and SUV(mean). These results will need to be validated in larger cohorts in a prospective study.

Developing a clinical and PET/CT volumetric prognostic index for risk assessment and management of NSCLC patients after initial therapy.

BACKGROUND: Currently, individual clinical prognostic variables are used sequentially with risk-stratification after TNM staging in clinical practice for the prognostic assessment of patients with NSCLC, which is not effective for estimating the collective impact of multiple individual variables on patient outcomes. Here, we developed a clinical and PET/CT volumetric prognostic (CPVP) index that integrates the prognostic power of multiple clinical variables and metabolic tumor volume from baseline FDG-PET, for use immediately after definitive therapy. PATIENTS AND METHODS: This retrospective cohort study included 998 NSCLC patients diagnosed between 2004 and 2017, randomly assigned to two cohorts for modeling the CPVP index using Cox regression models examining overall survival (OS) and subsequent validation. RESULTS: The CPVP index generated from the model cohort included pretreatment variables (whole-body metabolic tumor volume [MTVwb], clinical TNM stage, tumor histology, performance status, age, race, gender, smoking history) and treatment type. A clinical variable (CV) index without MTVwb and PET/CT volumetric prognostic (PVP) index without clinical variables were also generated for comparison. In the validation cohort, univariate Cox modeling showed a significant association of the index with overall survival (OS; Hazard Ratio [HR] 3.14; 95% confidence interval [95% CI] = 2.71 to 3.65, p < 0.001). Multivariate Cox regression analysis demonstrated a significant association of the index with OS (HR = 3.13, 95% CI = 2.66 to 3.67, p < 0.001). The index showed greater prognostic power (C-statistic = 0.72) than any of its independent variables including clinical TNM stage (C-statistic ranged from 0.50 to 0.69, all p < 0.003), CV index (C-statistic = 0.68, p < 0.001) and PVP index (C-statistic = 0.70, p = 0.006). CONCLUSIONS: The CPVP index for NSCLC patients has moderately strong prognostic power and is more prognostic than its individual prognostic variables and other indices. It provides a practical tool for quantitative prognostic assessment after initial treatment and therefore may be helpful for the development of individualized treatment and monitoring strategy for NSCLC patients.

Progressive Multiple Mononeuropathy in a Patient With Familial Transthyretin Amyloidosis After Liver Transplantation.

ABSTRACT: Valine 122 isoleucine (V122I) is the most common mutation associated with familial transthyretin-related amyloidosis (fATTR) in the metropolitan United States. V122I-related fATTR usually presents with cardiomyopathy. When polyneuropathy is encountered, it is usually mild, distal, and axonal in nature. Although liver transplantation improves survival for fATTR neuropathy patients, neuropathy may progress post liver transplantation because of the deposition of wild-type transthyretin. We report a patient with homozygous V122I mutation who presented with asymmetrical, upper limb predominant neuropathy rather early in his disease course, which progressed for a period of 5 years after liver transplantation before stabilization with the initiation of patisiran.

Clinical utility of temporal subtraction images in successive whole-body bone scans: evaluation in a prospective clinical study.

In order to aid radiologists' routine work for interpreting bone scan images, we developed a computerized method for temporal subtraction (TS) images which can highlight interval changes between successive whole-body bone scans, and we performed a prospective clinical study for evaluating the clinical utility of the TS images. We developed a TS image server which includes an automated image-retrieval system, an automated image-conversion system, an automated TS image-producing system, a computer interface for displaying and evaluating TS images with five subjective scales, and an automated data-archiving system. In this study, the radiologist could revise his/her report after reviewing the TS images if the findings on the TS image were confirmed retrospectively on our clinical picture archiving and communication system. We had 256 consenting patients of whom 143 had two or more whole-body bone scans available for TS images. In total, we obtained TS images successfully in 292 (96.1%) pairs and failed to produce TS images in 12 pairs. Among the 292 TS studies used for diagnosis, TS images were considered as "extremely beneficial" or "somewhat beneficial" in 247 (84.6%) pairs, as "no utility" in 44 pairs, and as "somewhat detrimental" in only one pair. There was no TS image for any pairs that was considered "extremely detrimental." In addition, the radiologists changed their initial reported impression in 18 pairs (6.2%). The benefit to the radiologist of using TS images in the routine interpretation of successive whole-body bone scans was significant, with negligible detrimental effects.

Prevalence of newly diagnosed sarcoidosis in patients with ventricular arrhythmias: a cardiac magnetic resonance and 18F-FDG cardiac PET study.

Cardiac sarcoidosis (CS) is known to be associated with ventricular tachycardia (VT); however, most investigations to date have focused on patients with known extra-cardiac sarcoidosis. The presence of CS is typically evaluated using 18F-fluorodeoxyglucose (18F-FDG) uptake on cardiac positron emission tomography (PET) or late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR). In this study, we sought to determine the prevalence of primary CS and the relationship between myocardial 18F-FDG uptake and LGE in patients with VT without known sarcoidosis. We retrospectively identified 67 patients without known sarcoidosis or active ischemic heart disease (i.e. significant ischemic disease that had not been previously revascularized) referred for both CMR and PET for evaluation of VT. Standard cine- and LGE- CMR and cardiac PET protocols were used. Myocardial LGE was defined as signal intensity > 5 SDs above the mean signal intensity of normal myocardium. Cardiac PET images were considered positive if there was focal myocardial 18F-FDG uptake having greater activity than the left ventricular blood pool. 45 patients (67%) had LGE, while only 4 (6%) had myocardial FDG uptake. Nine percent of patients with LGE had FDG-uptake while none without LGE did, and 10% of the cohort had indeterminate FDG uptake presumably from poor dietary preparation. Of those with both FDG uptake and LGE, 3/4 ultimately received a clinical diagnosis of CS. 4.5% of patients without previously known sarcoidosis or active ischemic heart disease presenting with VT have newly diagnosed CS. Detection of CS can be increased using a CMR first approach followed by cardiac PET for patients with non-ischemic LGE.

Interobserver variability among measurements of the maximum and mean standardized uptake values on (18)F-FDG PET/CT and measurements of tumor size on diagnostic CT in patients with pulmonary tumors.

BACKGROUND: (18)F-fluoro-2-deoxyglucose positron emission tomography ((18)F-FDG PET) imaging has been shown to be an accurate method for diagnosing pulmonary lesions, and the standardized uptake value (SUV) has been shown to be useful in differentiating benign from malignant lesions. PURPOSE: To survey the interobserver variability of SUV(max) and SUV(mean) measurements on (18)F-FDG PET/CT scans and compare them with tumor size measurements on diagnostic CT scans in the same group of patients with focal pulmonary lesions. MATERIAL AND METHODS: Forty-three pulmonary nodules were measured on both (18)F-FDG PET/CT and diagnostic chest CT examinations. Four independent readers measured the SUV(max) and SUV(mean) of the (18)F-FDG PET images, and the unidimensional nodule size of the diagnostic CT scans (UD(CT)) in all nodules. The region of interest (ROI) for the SUV measurements was drawn manually around each tumor on all consecutive slices that contained the nodule. The interobserver reliability and variability, represented by the intraclass correlation coefficient (ICC) and coefficient of variation (COV), respectively, were compared among the three parameters. The correlation between the SUV(max) and SUV(mean) was also analyzed. RESULTS: There was 100% agreement in the SUV(max) measurements among the 4 readers in the 43 pulmonary tumors. The ICCs for the SUV(max), SUV(mean), and UD(CT) by the four readers were 1.00, 0.97, and 0.97, respectively. The root-mean-square values of the COVs for the SUV(max), SUV(mean), and UD(CT) by the four readers were 0%, 13.56%, and 11.03%, respectively. There was a high correlation observed between the SUV(max) and SUV(mean) (Pearson's r=0.958; P <0.01). CONCLUSION: This study has shown that the SUV(max) of lung nodules can be calculated without any interobserver variation. These findings indicate that SUV(max) is a more valuable parameter than the SUV(mean) or UD(CT) for the evaluation of therapeutic effects of chemotherapy or radiation therapy on serial studies.

Development of a computer-aided diagnostic scheme for detection of interval changes in successive whole-body bone scans.

Bone scintigraphy is the most frequent examination among various diagnostic nuclear medicine procedures. It is a well-established imaging modality for the diagnosis of osseous metastasis and for monitoring osseous tumor response to chemotherapy and radiation therapy. Although the sensitivity of bone scan examinations for detection of bone abnormalities has been considered to be relatively high, it is time consuming to identify multiple lesions such as bone metastases of prostate and breast cancers. In addition, it is very difficult to detect subtle interval changes between two successive abnormal bone scans, because of variations in patient conditions, the accumulation of radioisotopes during each examination, and the image quality of gamma cameras. Therefore, we developed a new computer-aided diagnostic (CAD) scheme for the detection of interval changes in successive whole-body bone scans by use of a temporal subtraction image which was obtained with a nonlinear image-warping technique. We carried out 58 pairs of successive bone scans in which each scan included both posterior and anterior views. We determined 107 "gold-standard" interval changes among the 58 pairs based on the consensus of three radiologists. Our computerized scheme consisted of seven steps, i.e., initial image density normalization on each image, image matching for the paired images, temporal subtraction by use of the nonlinear image-warping technique, initial detection of interval changes by use of temporal-subtraction images, image feature extraction of candidates of interval changes, rule-based tests by use of 16 image features for removing some false positives, and display of the computer output for identified interval changes. One hundred seven gold standard interval changes included 71 hot lesions (uptake was increased compared with the previous scan, or there was new uptake in the current scan) and 36 cold lesions (uptake was decreased or disappeared) for anterior and posterior views. The overall sensitivity in the detection of interval changes, including both hot and cold lesions evaluated by use of the resubstitution and the leave-one-case-out methods, were 95.3%, with 5.97 false positives per view, and 83.2% with 6.02, respectively. The temporal subtraction image for successive whole-body bone scans has the potential to enhance the interval changes between two images, which also can be quantified. Furthermore, the CAD scheme for the detection of interval changes by use of temporal subtraction images would be useful in assisting radiologists' interpretation on successive bone scan images.

Usefulness of temporal subtraction images for identification of interval changes in successive whole-body bone scans: JAFROC analysis of radiologists' performance.

RATIONALE AND OBJECTIVES: We evaluated the usefulness of temporal subtraction images obtained from two successive whole-body bone scans, in terms of improvement in radiologists' diagnostic accuracy in detecting interval changes and of a reduction in reading time, by use of a jackknife free-response receiver operating characteristic (JAFROC) analysis method. MATERIALS AND METHODS: Twenty pairs of successive whole-body bone scans (72 consented interval changes) and their temporal subtraction images were used for an observer performance study. Our institutional review board approved the use of this database and the participation of radiologists in this study. In the first session of the observer study, without temporal subtraction images, the previous and current images were shown to five radiologists independently for their marking of the locations on current images and confidence ratings on potential interval changes from previous images. In the second session, temporal subtraction images were shown together with the modified previous and current images. JAFROC analysis was used for assessing the statistical significance of differences between radiologists' performance without and with temporal subtraction images. RESULTS: The average sensitivity for detecting interval changes was improved from 58.6% to 73.2% at a false-positive rate of two per case by use of temporal subtraction images, and the difference was statistically significant by use of JAFROC analysis (P = .035). In addition, the mean reading time per case was reduced considerably from 134 seconds to 91 seconds (P < .01). CONCLUSIONS: Temporal subtraction imaging for successive whole-body bone scans has the potential greatly to assist radiologists by increasing both their accuracy and productivity.

Integrating PET and CT information to improve diagnostic accuracy for lung nodules: A semiautomatic computer-aided method.

UNLABELLED: Our objective was to develop and evaluate 3 semiautomatic computer-aided diagnostic (CAD) schemes for distinguishing between benign and malignant pulmonary nodules by use of features extracted from CT, 18F-FDG PET, and both CT and 18F-FDG PET. METHODS: We retrospectively collected 92 consecutive cases of pulmonary nodules (<3 cm) in patients who underwent both thoracic CT and whole-body PET/CT. Forty-two of the nodules were malignant and 50 benign, as confirmed by pathologic examination and clinical follow-up. The interval between CT and PET was less than 1 mo. Four clinical parameters, including patient age, sex, smoking status, and history of previous malignancy, were used for the CAD schemes. Sixteen CT features based on size, shape, margin, and internal structure of nodules were independently rated subjectively by 2 chest radiologists. Four PET features were viewed on a PET/CT workstation. CAD schemes based on clinical parameters together with CT features, PET features, and both CT and PET features were then used to differentiate benign from malignant nodules. Finally, the output from the CAD schemes was evaluated by use of receiver-operating-characteristic analysis. RESULTS: When we used clinical parameters and CT features as input units (CAD scheme 1), the area under the receiver-operating-characteristic curve (A(z) value) of the CAD scheme was 0.83. When we used clinical parameters and PET features as input units (CAD scheme 2), the A(z) value for the computer output was 0.91. However, when we used all data as input units (CAD scheme 3), the A(z) value for the computer output was 0.95. The performance of CAD scheme 3 was better than that of CAD scheme 1 or 2. A statistically significant difference existed between the A(z) values of CAD schemes 3 and 2 (P = 0.037) and between those of CAD schemes 3 and 1 (P = 0.015). CONCLUSION: Our CAD scheme based on both PET and CT was better able to differentiate benign from malignant pulmonary nodules than were the CAD schemes based on PET alone and CT alone.