FDG-PET/CT and MRI for Evaluation of Pathologic Response to Neoadjuvant Chemotherapy in Patients With Breast Cancer: A Meta-Analysis of Diagnostic Accuracy Studies.

INTRODUCTION: This study compared the diagnostic test accuracy of magnetic resonance imaging (MRI) with that of (18)F-fluoro-2-glucose-positron emission tomography/computed tomography (FDG-PET/CT) imaging in assessment of response to neoadjuvant chemotherapy (NAC) in breast cancer. METHODS: A systematic search was performed in PubMed and EMBASE (last updated in June 2015). Studies investigating the performance of MRI and FDG-PET or FDG-PET/CT imaging during or after completion of NAC in patients with histologically proven breast cancer were eligible for inclusion. We considered only studies reporting a direct comparison between these imaging modalities to establish precise summary estimates in the same setting of patients. Pathologic response was considered as the reference standard. Two authors independently screened and selected studies that met the inclusion criteria and extracted the data. RESULTS: A total of 10 studies were included. The pooled estimates of sensitivity and specificity across all included studies were 0.71 and 0.77 for FDG-PET/CT (n = 535) and 0.88 and 0.55 for MRI (n = 492), respectively. Studies were subgrouped according to the time of therapy assessment. In the intra-NAC setting, FDG-PET/CT imaging outperformed MRI with fairly similar pooled sensitivity (0.91 vs. 0.89) and higher specificity (0.69 vs. 0.42). However, MRI appeared to have higher diagnostic accuracy than FDG-PET/CT imaging when performed after the completion of NAC, with significantly higher sensitivity (0.88 vs. 0.57). CONCLUSION: Analysis of the available studies of patients with breast cancer indicates that the timing of imaging for NAC-response assessment exerts a major influence on the estimates of diagnostic accuracy. FDG-PET/CT imaging outperformed MRI in intra-NAC assessment, whereas the overall performance of MRI was higher after completion of NAC, before surgery. IMPLICATIONS FOR PRACTICE: The timing of therapy assessment imaging exerts a major influence on overall estimates of diagnostic accuracy. (18)F-fluoro-2-glucose-positron emission tomography (FDG-PET)/computed tomography (CT) imaging outperformed magnetic resonance imaging (MRI) in intra-neoadjuvant chemotherapy assessment with fairly similar pooled sensitivity and higher specificity. However, MRI appeared to be more accurate than FDG-PET/CT in predicting pathologic response when used in the post-therapy setting.

FDG Avidity and Tumor Burden: Survival Outcomes for Patients With Recurrent Breast Cancer.

OBJECTIVE: The objective of this study was to assess the value of quantitative PET parameters in the prediction of survival for patients with recurrent breast cancer. MATERIALS AND METHODS: We conducted a retrospective study of 78 women who had recurrent breast cancer identified by biopsy or follow-up examinations from 2000 to 2012. The maximum and peak standardized uptake values (SUVmax and SUVpeak, respectively), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured for each recurrent lesion at primary, nodal, and distant metastatic sites, with the use of the gradient segmentation method. The optimum cutoff point (i.e., the value with the maximum Youden index, defined as sensitivity plus specificity minus 1) was calculated using the ROC curve. The median follow-up duration was 28.5 months (range, 0-94 months). The primary outcome measure was overall survival (OS). Kaplan-Meier survival plots and Cox regression analyses were performed. RESULTS: The mean (± SD) values noted for the study population were as follows: an SUVmax of 6.70 ± 4.1, an SUVpeak of 5.12 ± 3.4, total lesion glycolysis of all recurrent lesions (TLGtotal) of 359.73 ± 1114.4 g, and metabolic tumor volume of all recurrent lesions (MTVtotal) of 68.04 ± 144.9 mL. The mean OS for patients who died was 25.5 months, whereas for patients who survived, it was 36.7 months (p = 0.04). Univariate analysis showed that age (p = 0.02), optimum SUVmax (p = 0.006), SUVpeak (p = 0.006), and TLGtotal (p = 0.034) were associated with OS; however, none of the factors remained statistically significant in multivariate analysis. Kaplan-Meier survival analysis was performed, and the SUVmax (threshold, 2.9; hazard ratio [HR], 5.2 [95% CI, 1.6-16.7]; p = 0.002), SUVpeak (threshold, 2.34; HR, 4.3 [95% CI, 1.5-12]; p = 0.002), and TLG (threshold, 11.85 g; HR, 2.8 [95% CI, 1.0-7.1]; p = 0.025) were statistically significant predictors of death during follow-up. An integrated risk stratification model with FDG avidity (SUVmax) and MTVtotal divided into three subgroups of patients predicted patient survival outcomes (HR, 2.48 [95% CI, 1.38-4.46]; p = 0.005, by log-rank test). CONCLUSION: FDG PET-determined SUVmax, SUVpeak, and TLG values and an integrated risk stratification scheme using FDG avidity and total tumor burden appear to provide prognostic survival information for patients with recurrent breast cancer.

JOURNAL CLUB: Value of Quantitative FDG PET/CT Volumetric Biomarkers in Recurrent Colorectal Cancer Patient Survival.

OBJECTIVE: The purpose of this study was to evaluate the impact of quantitative PET parameters in the overall survival of patients with recurrent colorectal cancer. MATERIALS AND METHODS: A total of 105 patients with a biopsy-proven recurrence of colorectal cancer who underwent PET/CT were included in the study. A gradient segmentation method was used to calculate maximum and peak standardized uptake values (SUVmax, SUVpeak), total lesion glycolysis (TLGtotal), and metabolic tumor volume (MTVtotal). These parameters were measured for each recurrent lesion at the primary, locoregional, and distant sites. The median follow-up time was 31.3 months. Overall survival (OS) was the primary outcome and was calculated using Kaplan-Meier survival plots and Cox regression analyses. RESULTS: The mean ± SD for SUVmax, SUVpeak, TLGtotal, and MTVtotal of the included patients was 7.3 ± 5.3, 5.3 ± 3.3, 280.8 ± 1181 g, and 79.8 ± 294 mL, respectively. The median OS for patients who were alive was 50 months in comparison with 23.4 months among patients who died. Age (p = 0.041), tumor grade (p = 0.010), median TLG (p = 0.031), and median MTV (p = 0.009) remained significantly associated with OS in the multivariate Cox regression analysis. Kaplan-Meier survival analysis performed on the basis of the median PET/CT parametric values showed that SUVmax (threshold, 5.63; hazard ratio [HR] = 1.7; 95% CI, 1-2.8; p = 0.02), MTVtotal (threshold, 13.85 mL; HR = 2.2; 95% CI, 1.3-3.9; p = 0.003), and TLGtotal (threshold, 36.14 g; HR = 1.9; 95% CI, 1.1-3.3; p = 0.01) were significant predictors of OS during follow-up. An integrated risk stratification model with SUVmax and MTVtotal into three subgroups predicted patient survival outcomes (HR = 1.8; 95% CI, 1.25-2.65; log-rank p = 0.003). CONCLUSION: SUVmax, MTVtotal, TLGtotal, and integrated score with FDG avidity and total tumor burden provide survival information for patients with biopsy-proven recurrent colorectal cancer.

FDG PET/CT in Patients With Head and Neck Squamous Cell Carcinoma After Primary Surgical Resection With or Without Chemoradiation Therapy.

OBJECTIVE: The purpose of this study was to assess the value of posttreatment FDG PET/CT in patients with squamous cell carcinoma of the head and neck (HNSCC) treated with primary surgical resection with or without adjuvant concurrent chemoradiotherapy. MATERIALS AND METHODS: A total of 98 HNSCC patients were treated with primary surgical resection and had undergone PET/CT within 6 months of treatment completion. The accuracy of the scans and the added value to clinical assessment and impact on management were established based on the clinical information before and after each scan. Overall survival of patients was estimated with Kaplan-Meier curves. RESULTS: Of the total 98 scans, 25 (25.5%) were interpreted as positive and 73 (74.5%) as negative. The sensitivity of posttreatment PET/CT was 80.0%; specificity, 89.5%; positive predictive value, 66.7%; negative predictive value, 94.4%; and accuracy, 87.5%. These scans were helpful in excluding tumor in 31.8% of patients with clinical suspicion of residual disease and identifying suspected residual disease in 13.2% of patients with no prior clinical suspicion. Multivariate regression analysis showed that tumor size, grade (p = 0.041), scan type (p = 0.002), and scan result (p = 0.005) were independent covariates associated with overall survival. Kaplan-Meier analysis showed a significant difference and association in overall survival between patients with a positive versus a negative posttherapy PET/CT scan result (hazard ratio, 5.65; 95% CI, 2.48-12.83; log rank Mantel-Cox p < 0.001). CONCLUSION: Posttreatment FDG PET/CT results had a high negative predictive value, added value to clinical assessment of 35% of patients, influenced subsequent management, and were associated with survival outcome of HNSCC patients treated with primary surgical resection.

Diagnostic Accuracy of Follow-Up FDG PET or PET/CT in Patients With Head and Neck Cancer After Definitive Treatment: A Systematic Review and Meta-Analysis.

OBJECTIVE: The purpose of this study was to assess the diagnostic performance of FDG PET or PET/CT for detection of local, regional, and distant recurrences in the follow-up of patients with head and neck cancer who underwent definitive treatment. MATERIALS AND METHODS: A systematic search was performed in MEDLINE and Cochrane Library (updated September 2014) to identify relevant published studies. Studies investigating the accuracy of FDG PET/CT that were performed at least 4 months after therapy were included. Two authors independently screened all retrieved articles, selected studies that met the inclusion criteria, and extracted the data. Histopathologic confirmation or clinical follow-up of at least 6 month (or both) was considered as the reference standard. RESULTS: Twenty-three studies constituting a total of 2247 FDG PET/CT examinations met our inclusion criteria. The pooled sensitivity and specificity of follow-up PET/CT for detection of recurrence were 0.92 (95% CI, 0.90-0.94), and 0.87 (95% CI, 0.82-0.91), respectively. The pooled sensitivity and specificity of scans performed 4-12 months after treatment were 0.95 (95% CI, 0.91-0.97) and 0.78 (95% CI, 0.70-0.84), respectively. Similar estimates for scans performed at or more than 12 months after treatment were 0.92 (95% CI, 0.85-0.96) and 0.91 (95% CI, 0.78-0.96), respectively. The overall accuracy of FDG PET/CT in detecting recurrence is higher in patients without suspicion of recurrence before the scan compared with the patients with suspected recurrence. CONCLUSION: The high diagnostic performance of FDG PET/CT in detecting recurrence in curatively treated patients with head and neck cancer supports its use in clinical practice for patient follow-up. Further studies are needed to evaluate the prognostic utility of PET/CT in the follow-up of head and neck cancer.

Multiparametric ultrasound for upper extremity dialysis access evaluation.

The evolution of ultrasound (US) techniques has greatly improved the evaluation of many parameters in dialysis vascular access, which is typically achieved through an arteriovenous fistula (AVF) or graft (AVG). These techniques include grayscale B-mode, color Doppler, power Doppler, spectral Doppler, non-Doppler US flow imaging techniques, contrast-enhanced US, and elastography. In conjunction with a patient's medical history and physical examination, US provides crucial information about the native vascular bed prior to the surgical creation of an arteriovenous anastomosis. It also tracks the maturation progress of the newly created AVF or AVG and aids in diagnosing potential complications of the vascular access. These complications include thrombosis, steal syndrome, aneurysms, pseudoaneurysms, hematomas, infection, ischemic neuropathy, exacerbation of preexisting congestive heart failure, and stenosis.

Utilizing dual energy CT to distinguish blood from contrast leakage following middle meningeal artery embolization for chronic subdural hematomas.

BACKGROUND: Recently, middle meningeal artery (MMA) embolization has emerged as a potential alternative treatment option for chronic subdural hematomas (SDH). Imaging following MMA embolization often shows high density material in the subdural space, usually representing contrast leakage through the dura or, less commonly, hemorrhage. These cannot be reliably differentiated on conventional CT. Dual energy CT (DECT) provides the ability to differentiate materials that otherwise appear similar on conventional CT such as blood and iodine. METHODS: A retrospective review was conducted to evaluate patients who underwent MMA embolization for SDH between May 2019 and April 2020. Post-procedural head CT performed on an IQon Elite Spectral CT detector-based DECT scanner enabled two-material decomposition to separate iodine from blood. The dual energy reconstructions used included the virtual non-contrast and iodine no-water images. RESULTS: Four representative illustrative cases were selected to highlight the ability of DECT to characterize new hyperdensity on head CT following MMA embolization as blood, contrast or a combination. CONCLUSIONS: DECT allows objective differentiation of contrast leakage from blood following MMA embolization. This technology can obviate the need for additional follow-up scanning and prolonged patient observation, which in turn can result in reduced costs and radiation exposure to patients.

Superior hypogastric nerve block (SHNB) for pain control after uterine fibroid embolization (UFE): technique and troubleshooting.

BACKGROUND: Superior Hypogastric nerve Block (SHNB) has been shown to be an effective pain management technique after Uterine Fibroid Embolization (UFE), reducing the need for opiates and allowing same-day discharge after UFE. In this technical note we discuss relevant anatomy and technical details in performing SHNB. MAIN BODY: The Superior hypogastric plexus (SHP) is the part of the abdominopelvic sympathetic nervous system that provides a targeted intervention to sympathetic-mediated pain pathways of pelvic organs and a target for an anterior approach Superior Hypogastric nerve Block after embolization. Vascular structures are in close relation to the intended site of target of the SHP at the L5 vertebral body include aortic bifurcation and IVC confluence, hence a detailed knowledge of this is essential. A step by step technical approach to SHNB includes patient positioning for the block, image guidance and needle positioning, choice and technique of anesthetic injection. Traversing a large fibroid uterus, inadvertent vascular opacification and Local anesthetic systemic toxicity present challenges to performing the block and are addressed. CONCLUSION: Superior Hypogastric nerve Block (SHNB) can be a useful tool in the Interventional armamentarium to make UFE a better experience for patients with fibroids, allowing for better pain control as well as facilitating same day discharge. Performing SHNB appear to be can be performed with technical ease for an interventional radiologist.

Investigating the role of DCE-MRI, over T2 and DWI, in accurate PI-RADS v2 assessment of clinically significant peripheral zone prostate lesions as defined at radical prostatectomy.

PURPOSE: PI-RADS v2 dictates that dynamic contrast-enhanced (DCE) imaging be used to further classify peripheral zone (PZ) cases that receive a diffusion-weighted imaging equivocal score of three (DWI3), a positive DCE resulting in an increase in overall assessment score to a four, indicative of clinically significant prostate cancer (csPCa). However, the accuracy of DCE in predicting csPCa in DWI3 PZ cases is unknown. This study sought to determine the frequency with which DCE changes the PI-RADS v2 DWI3 assessment category, and to determine the overall accuracy of DCE-MRI in equivocal PZ DWI3 lesions. MATERIALS AND METHODS: This is a retrospective study of patients with pathologically proven PCa who underwent prostate mpMRI at 3T and subsequent radical prostatectomy. PI-RADS v2 assessment categories were determined by a radiologist, aware of a diagnosis of PCa, but blinded to final pathology. csPCa was defined as a Gleason score ≥ 7 or extra prostatic extension at pathology review. Performance characteristics and diagnostic accuracy of DCE in assigning a csPCa assessment in PZ lesions were calculated. RESULTS: A total of 271 men with mean age of 59 ± 6 years mean PSA 6.7 ng/mL were included. csPCa was found in 212/271 (78.2%) cases at pathology, 209 of which were localized in the PZ. DCE was necessary to further classify (45/209) of patients who received a score of DWI3. DCE was positive in 29/45 cases, increasing the final PI-RADS v2 assessment category to a category 4, with 16/45 having a negative DCE. When compared with final pathology, DCE was correct in increasing the assessment category in 68.9% ± 7% (31/45) of DWI3 cases. CONCLUSION: DCE increases the accuracy of detection of csPCa in the majority of PZ lesions that receive an equivocal PI-RADS v2 assessment category using DWI.

Predictive role of PI-RADSv2 and ADC parameters in differentiating Gleason pattern 3 + 4 and 4 + 3 prostate cancer.

PURPOSE: To compare the predictive roles of qualitative (PI-RADSv2) and quantitative assessment (ADC metrics), in differentiating Gleason pattern (GP) 3 + 4 from the more aggressive GP 4 + 3 prostate cancer (PCa) using radical prostatectomy (RP) specimen as the reference standard. METHODS: We retrospectively identified treatment-naïve peripheral (PZ) and transitional zone (TZ) Gleason Score 7 PCa patients who underwent multiparametric 3T prostate MRI (DWI with b value of 0,1400 and where unavailable, 0,500) and subsequent RP from 2011 to 2015. For each lesion identified on MRI, a PI-RADSv2 score was assigned by a radiologist blinded to pathology data. A PI-RADSv2 score ≤ 3 was defined as "low risk," a PI-RADSv2 score ≥ 4 as "high risk" for clinically significant PCa. Mean tumor ADC (ADCT), ADC of adjacent normal tissue (ADCN), and ADCratio (ADCT/ADCN) were calculated. Stepwise regression analysis using tumor location, ADCT and ADCratio, b value, low vs. high PI-RADSv2 score was performed to differentiate GP 3 + 4 from 4 + 3. RESULTS: 119 out of 645 cases initially identified met eligibility requirements. 76 lesions were GP 3 + 4, 43 were 4 + 3. ADCratio was significantly different between the two GP groups (p = 0.001). PI-RADSv2 score ("low" vs. "high") was not significantly different between the two GP groups (p = 0.17). Regression analysis selected ADCT (p = 0.03) and ADCratio (p = 0.0007) as best predictors to differentiate GP 4 + 3 from 3 + 4. Estimated sensitivity, specificity, and accuracy of the predictive model in differentiating GP 4 + 3 from 3 + 4 were 37, 82, and 66%, respectively. CONCLUSIONS: ADC metrics could differentiate GP 3 + 4 from 4 + 3 PCa with high specificity and moderate accuracy while PI-RADSv2, did not differentiate between these patterns.

Post-treatment 18F-FDG-PET/CT versus contrast-enhanced CT in patients with oropharyngeal squamous cell carcinoma: comparative effectiveness study.

OBJECTIVE: To compare the accuracy of same-day therapy-assessment PET/computed tomography (PET/CT) and conventional contrast-enhanced computed tomography (CECT) in patients with oropharyngeal squamous cell carcinoma (OPSCC). METHODS: A total of 110 (95 men and 15 women; mean age 59 years) patients with biopsy-proven OPSCC were evaluated with same-day PET/CT and CECT pair scans as part of follow-up therapy assessment. Scans were performed within 6 months after the completion of primary treatment (median time: 3.1 months; range: 0.5-6 months). PET/CT and CECT scans were reviewed retrospectively for residual primary site disease, and right and left cervical lymph node involvement. Histopathology or 6 month clinical/imaging follow-up were used as the gold standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated for the primary site and cervical nodal disease. RESULTS: Of 110 OPSCC patients, 90.9% were human papilloma virus positive, 80.8% were stage 4, and 76.4% received chemoradiation as the primary treatment. The sensitivity, specificity, PPV, NPV, and accuracy of PET/CT and CECT were similar in the evaluation of the primary cancer site (PET/CT: 75.0, 91.5, 25.0, 99.0, and 90.9, respectively, versus CECT: 75.0, 90.6, 23.1, 99.0, and 90.0, respectively). In evaluating cervical lymph node involvement, PET/CT appeared to have higher accuracy (96.8 vs. 81.7%), specificity (97.7 vs. 81.7%), and PPV (45.8 vs. 16.5%), comparable NPV (99.4% for both), and lower sensitivity (65 vs. 75%) compared with same-day CECT. CONCLUSION: Same-day PET/CT and CECT scans had comparable accuracy in the evaluation of primary tumor sites after completion of therapy in patients with OPSCC. PET/CT showed higher accuracy in the evaluation of cervical lymph node involvement.

Value of Intratumoral Metabolic Heterogeneity and Quantitative 18F-FDG PET/CT Parameters to Predict Prognosis in Patients With HPV-Positive Primary Oropharyngeal Squamous Cell Carcinoma.

OBJECTIVE: The aim of this study was to evaluate the impact of intratumoral metabolic heterogeneity and quantitative FDG PET/CT imaging parameters for predicting patient outcomes in primary oropharyngeal squamous cell cancer (OPSCC). PATIENTS AND METHODS: We retrospectively investigated 105 patients with HPV-positive OPSCC. SUVmax and metabolic tumor volume (MTV) were measured for the primary tumors and when available for the metastatic sites. Primary tumor intratumoral metabolic heterogeneity was calculated as the area under a cumulative SUV volume histograms curve (AUC-CSH). The median follow-up time was 35.4 months (range, 3-92 months). Outcome end point was event-free survival (EFS). Kaplan-Meier survival plots and Cox regression analyses were performed. RESULTS: Of the 105 patients included, 19 patients relapsed and 11 deceased during the study period. AUC-CSH indexes were associated with EFS using PET gradient-based (P = 0.034) and 50% threshold (P = 0.02) segmentation methods, on multivariate analysis. Kaplan-Meier survival analysis using optimum cutoff of 16.7 SUVmax and 12.7 mL total MTV were significant predictors of EFS. Combining SUVmax and AUC-CSH index in 3 subgroups, patients with higher intratumoral heterogeneity and higher SUVmax were associated with worse outcome (log-rank, P = 0.026). Similarly, patients with higher intratumoral heterogeneity tumors and higher MTV had worse prognosis (log-rank, P = 0.022). CONCLUSIONS: Intratumoral metabolic heterogeneity using FDG PET was a prognostic factor for EFS in patients with primary HPV (+) OPSCC. The combined predictive effect of FDG avidity, metabolic tumor burden, and intratumoral heterogeneity provided prognostic survival information in these patients.

Comparative effectiveness: 18F-FDG-PET/CT versus CT for post-treatment follow-up of patients with lung cancer.

PURPOSE: This study aimed to evaluate the comparative effectiveness of follow-up fluorine-18-fluorodeoxyglucose (F-FDG)-PET/CT and chest CT in the detection of local, regional, and distant metastatic diseases in lung cancer. PATIENTS AND METHODS: Follow-up F-FDG-PET/CT and chest-CT pairs of biopsy-proven lung cancer patients were reviewed retrospectively (May 2004-June 2013). Histopathological, clinical, or imaging follow-up data of at least 6 months was considered the reference standard. The κ statistics, the percentage agreement between the two techniques, and per-scan basis diagnostic performances were reported. RESULTS: A total of 270 patients with a total of 423 paired F-FDG-PET/CT and chest-CT scans were included (median time interval between two scans=2 days). The two imaging modalities showed concordance of 82.7% (κ=0.71) for local disease, 82% (κ=0.65) for regional disease, and 77.3% (κ=0.55) for distant metastasis. Overall, F-FDG-PET/CT identified more lesions compared with chest CT both in the regional lymph nodes (308 vs. 204 regional zone involvement) and in cases of distant metastasis (253 vs. 182 metastatic sites). In the evaluation of local disease, F-FDG-PET/CT appeared to have fairly similar sensitivity (96 vs. 95.4%) and specificity (82.1 vs. 83%) compared with chest CT. In the evaluation of regional lymph nodes and distant metastases, F-FDG-PET/CT showed higher sensitivity (regional nodes: 96 vs. 89.8%; distant metastases: 91.9 vs. 70.7%) and comparable specificity (regional nodes: 87.1 vs. 88.9%; distant metastases: 87.1 vs.88.1%). CONCLUSION: The sensitivity of F-FDG-PET/CT is superior to that of chest CT in the detection of regional and distant metastasis, while having comparable specificity.

Molecular Imaging and Precision Medicine: PET/Computed Tomography and Therapy Response Assessment in Oncology.

A variety of methods have been developed to assess tumor response to therapy. Standardized qualitative criteria based on 18F-fluoro-deoxyglucose PET/computed tomography have been proposed to evaluate the treatment effectiveness in specific cancers and these allow more accurate therapy response assessment and survival prognostication. Multiple studies have addressed the utility of the volumetric PET biomarkers as prognostic indicators but there is no consensus about the preferred segmentation methodology for these metrics. Heterogeneous intratumoral uptake was proposed as a novel PET metric for therapy response assessment. PET imaging techniques will be used to study the biological behavior of cancers during therapy.

Clinical Indications and Impact on Management: Fourth and Subsequent Posttherapy Follow-up 18F-FDG PET/CT Scans in Oncology Patients.

The Centers for Medicare and Medicaid Services coverage includes 3 posttherapy 18F-FDG PET/CT scans per patient and per tumor type. Any additional follow-up 18F-FDG PET/CT scans will be reimbursed at the discretion of a local Medicare administrator, if deemed medically necessary. This study aimed to investigate common clinical indications for performing a fourth or additional follow-up 18F-FDG PET/CT scans that could affect the management of patients. Methods: This was a retrospective institutional review of 433 oncology patients (203 men; mean age, 55 y), including a total of 1,659 fourth or subsequent follow-up PET/CT scans after completion of primary treatment. Twelve indications for performing a fourth or subsequent follow-up PET/CT scan were determined, and the impact of each of the 12 indications on patients' management was evaluated. Results: The primary tumors were breast cancer (92 patients, 426 scans), non-Hodgkin lymphoma (77 patients, 208 scans), Hodgkin disease (41 patients, 182 scans), colorectal cancer (70 patients, 286 scans), melanoma (69 patients, 271 scans), and lung cancer (84 patients, 286 scans). The indications were categorized in 4 groups: PET/CT for diagnosis of tumor recurrence (303/1,659, 18.3%), PET/CT before starting therapy for tumor recurrence (64/1,659, 3.9%), PET/CT to assess therapy response for tumor recurrence (507/1,659, 30.6%), and follow-up PET/CT after completion of treatment for tumor recurrence (785/1,659, 47.3%). Overall, fourth and subsequent follow-up 18F-FDG PET/CT scans resulted in change in management in 31.6% of the scans (356 of 1,128) when the scans were obtained for medical necessities (indications 1-11), and in 5.6% of the scans (30/531) when the scans were obtained without any medical necessity (indication 12). Conclusion: The fourth and subsequent PET/CT scans obtained after completion of primary treatment led to a change in management in 31.6% of the scans when acquired for appropriate clinical reasons. Performing follow-up PET/CT without appropriate medical reason had a low impact on patients' management and should be avoided.

18F-FDG PET/CT Metabolic Tumor Volume and Intratumoral Heterogeneity in Pancreatic Adenocarcinomas: Impact of Dual-Time Point and Segmentation Methods.

OBJECTIVES: We aimed to determine the consistency of quantitative PET measurements of metabolic tumor volume (MTV) and intratumoral heterogeneity index for primary untreated pancreatic adenocarcinomas, when using dual-time point F-FDG PET/CT imaging. METHODS: This is an institutional review board-approved, retrospective study including 71 patients with pancreatic adenocarcinoma, who underwent dual-time point F-FDG PET/CT imaging, at approximately 1 hour (early) and 2 hours (delayed), after injection. Automated gradient-based and 50% SUVmax-threshold segmentation methods were used to assess the primary tumor MTV and metabolic intratumoral heterogeneity index, calculated as the area under cumulative SUV-volume histograms (AUC-CSH), with lower AUC-CHS indexes corresponding to higher degrees of tumor heterogeneity. We defined that more than a ±10% change in MTV or AUC-CSH, compared with baseline, as clinically significant. RESULTS: Seventy-one FDG-avid pancreatic tumors were identified, with an average tumor diameter of 3.4 ± 0.9 cm (range, 1.5-6.4 cm). Metabolic tumor volume values remained consistent between early and delayed imaging when using the gradient PET segmentation method (P = 0.086), whereas statistically significant change was seen when using 50% SUVmax-threshold segmentation (P < 0.001). A decrease in more than 10% change in MTV (% ΔMTV) was observed in 70.4% (50/71) tumors, and 7.0% (5/71) of the tumors showed an increase more than 10 % ΔMTV, when using the 50% SUVmax-threshold segmentation. AUC-CSH indexes showed statistically significant differences between early and delayed time points (P < 0.001), when using the gradient segmentation. AUC-CSH index decreased by 10% or greater in 40.8% (29/71) of the tumors. AUC-CSH index remained stable between early and delayed when using the 50% SUVmax-threshold segmentation (P = 0.148) with percentage of change of less than 10% for all tumors. CONCLUSIONS: Metabolic tumor volume was relatively stable between early and delayed time points when PET gradient segmentation was used but changed greater than 10% in 77.4% of the tumors at delayed time point when threshold segmentation was used. The tumor heterogeneity index (AUC-CSH) changed greater than 10% in 40.8% of tumors at delayed imaging, when gradient segmentation was used but remained stable when threshold segmentation was used. It is important to standardize uptake time and segmentation methods to use FDG PET MTV and heterogeneity index as imaging biomarkers.

Classification of Clinical Significance of MRI Prostate Findings Using 3D Convolutional Neural Networks.

Prostate cancer (PCa) remains a leading cause of cancer mortality among American men. Multi-parametric magnetic resonance imaging (mpMRI) is widely used to assist with detection of PCa and characterization of its aggressiveness. Computer-aided diagnosis (CADx) of PCa in MRI can be used as clinical decision support system to aid radiologists in interpretation and reporting of mpMRI. We report on the development of a convolution neural network (CNN) model to support CADx in PCa based on the appearance of prostate tissue in mpMRI, conducted as part of the SPIE-AAPM-NCI PROSTATEx challenge. The performance of different combinations of mpMRI inputs to CNN was assessed and the best result was achieved using DWI and DCE-MRI modalities together with the zonal information of the finding. On the test set, the model achieved an area under the receiver operating characteristic curve of 0.80.

Follow-up FDG PET/CT in Patients With Non-Hodgkin Lymphoma: Value to Clinical Assessment and Patient Management.

OBJECTIVE: The aim of this study was to evaluate the value of each follow-up PET/CT in the clinical assessment of recurrence as well as determining its impact on management in patients with non-Hodgkin lymphoma (NHL). PATIENTS AND METHODS: All patients diagnosed with NHL who had at least 1 follow-up PET/CT study, 6 months after primary treatment completion, were included. There were 204 eligible NHL patients with 560 follow-up PET/CT scans. The change in management was recorded after each follow-up PET/CT scan in comparison to the management plan before the study. RESULTS: Among the 560 scans, 388 scans (69.3%) were done without clinical suspicion and 172 scans (30.7%) were done with prior clinical suspicion of recurrence. Follow-up scan results suggested disease in 12.4% of the scans performed without clinical suspicion and ruled out disease in 16.3% scans performed with prior clinical suspicion. The management of NHL patients was changed after 37.8% of follow-up scans with prior clinical suspicion of recurrence and after 8.3% of scans in patients without prior clinical suspicion of recurrence. The management of NHL patients was not changed after 50.6% scans with prior clinical suspicion of recurrence of which 23.3% had no treatment before and after the scan and 27.3% had the same treatment continued before and after the scan. CONCLUSIONS: Follow-up FDG PET/CT performed with prior clinical suspicion of recurrence added value to patients with NHL for clinical assessment in 16.3% of the scan times and influenced the management in 37.8% of scan times. The management change was only 8.3% in patients without prior clinical suspicion of recurrence, and hence, surveillance FDG PET/CT in NHL should be avoided.

Value of fourth and subsequent post-therapy follow-up 18F-FDG PET/CT scans in patients with breast cancer.

OBJECTIVE: To evaluate the accuracy and value of the fourth and subsequent post-therapy follow-up fluorine-18 fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) scans in the clinical assessment of breast cancer patients. MATERIALS AND METHODS: Ninety-two female patients, with a total of 426 fourth and subsequent follow-up PET/CT scans, were retrospectively included. Patients were followed for a median of 23.7 months (range, 0.7-124.4) from the fourth follow-up PET/CT. The diagnostic accuracy of PET/CT, its impact on clinical assessment, patients' management, and survival outcome were established. RESULT: Of the 426 follow-up PET/CT scans, 264 (62%) were interpreted as positive and 162 (38%) were interpreted as negative. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the fourth and subsequent follow-up PET/CT scans were 97.7, 98.1, 98.8, 96.3, and 97.9%, respectively. Fourth and subsequent follow-up PET/CT were useful in excluding a tumor in 13.4% (39/292) of patients with a clinical suspicion of recurrence and identifying suspected recurrence in 10.5% (14/134) of patients without previous clinical suspicion. A change in management was noted in 6.7% (9/134) of scan times when the scans were performed without previous clinical suspicion of recurrence or therapy response and was 27.7% (81/292) when the scans were performed with clinical suspicion. Overall survival differed significantly between patients with all negative follow-up scans (n=23) and those who had at least one positive follow-up scan (n=69) (hazard ratio of 4.65, P<0.001). CONCLUSION: The fourth and subsequent PET/CT scans performed after the completion of primary treatment led to a change in management in 27.7% of patients when the scans were performed with clinical suspicion and only in 6.7% of patients when performed without clinical suspicion or context.

18F-FDG PET/CT and Melanoma: Value of Fourth and Subsequent Posttherapy Follow-up Scans for Patient Management.

PURPOSE: We aimed to evaluate the added value of performing fourth and subsequent follow-up F-FDG-PET/CT scans to clinical assessment and impact on the patient's management in patients with melanoma. METHODS: This was a retrospective study of 232 biopsy-proven melanoma patients who underwent F-FDG-PET/CT scans. Of these, 71 patients had 4 or more follow-up F-FDG-PET/CT scans after completion of primary treatment, with a total of 246 fourth or subsequent follow-up PET/CT scans. The added value of each follow-up PET/CT scan to the patient's clinical assessment and treatment management was established. Kaplan-Meier plots with a Mantel-Cox log-rank test were used to establish the patient's overall survival. RESULTS: Of the 246 fourth and subsequent follow-up PET/CT scans, 61% (150/246) were negative for malignancy, and 39.0% (96/246) were positive for recurrence/metastases. FDG-PET/CT was helpful in identifying malignancy in 6.5% of the scans performed without prior clinical suspicion, which ruled out malignancy in 28.5% of the scans obtained with prior clinical signs suggestive of recurrence or for secondary therapy assessment. The PET/CT scan resulted in change of the patient's management in approximately 16.7% (41/246) of the scans. Change in management was significantly greater in patients whose scans were done with prior clinical signs suggestive of malignancy, or for therapy assessment than without prior clinical suspicion (29.3% vs 4.1%; P < 0.0001). Statistically significant difference was seen in the overall survival between patients with at least 1 positive and all negative fourth and subsequent follow-up PET/CT scans at patient level (P = 0.001). CONCLUSIONS: The fourth and subsequent F-FDG-PET/CT scans obtained after completion of primary treatment added value to clinical assessment in patients with melanoma. Patients with clinical signs suggestive of recurrence or metastases or being monitored for treatment response are more likely to benefit from the fourth or subsequent FDG PET/CT than those without prior clinical suspicion.