Fluorine-18-Labeled Fluoroestradiol PET/CT: Current Status, Gaps in Knowledge, and Controversies-AJR Expert Panel Narrative Review.

PET/CT using 16α-[18F]-fluoro-17ß-estradiol (FES) noninvasively images tissues expressing estrogen receptors (ERs). FES has undergone extensive clinicopathologic validation for ER+ breast cancer and received FDA approval in 2020 for clinical use as an adjunct to biopsy in patients with recurrent or metastatic ER+ breast cancer. Clinical use of FES PET/CT is increasing, but is not widespread in the United States. This AJR Expert Panel Narrative Review explores the present status and future directions of FES PET/CT, including image interpretation, existing and emerging uses, knowledge gaps, and current controversies. Specific controversies discussed include whether both FES PET/CT and FDG PET/CT are warranted in certain scenarios, whether further workup is required after negative FES PET/CT results, whether FES PET/CT findings should inform endocrine therapy selection, and whether immunohistochemistry should remain the standalone reference standard for determining ER status for all breast cancers. Consensus opinions from the panel include agreement with the appropriate clinical uses of FES PET/CT published by a multidisciplinary expert workgroup in 2023; anticipated expanded clinical use of FES PET/CT for staging ER-positive invasive lobular carcinomas and low-grade invasive ductal carcinomas pending ongoing clinical trial results; and the need for further research regarding use of FES PET/CT for ER-expressing nonbreast malignancies.

FDG PET/CT-based Response Assessment in Malignancies.

Response is the logical outcome measure of a treatment in a clinical or research setting. Objective response assessment involves the use of a test to segregate patients who are likely to experience improved survival from those who are not. Early and accurate response assessment is critical for determining therapy effectiveness in clinical settings, for effective trial designs comparing two or more therapies, and for modulating treatment on the basis of response (ie, response-adapted therapy). 2-[fluorine 18]fluoro-2-deoxy-d-glucose (FDG) PET/CT can provide both functional and structural information about a disease process. It has been used at several stages of patient management, including imaging-based tumor response assessment, for various malignancies. FDG PET/CT can be used to differentiate patients with lymphoma who have a residual mass but no residual disease after treatment (ie, complete responders) from those who have a residual mass and residual disease after treatment. Similarly, in solid malignancies, the functional changes in glucose uptake and metabolism precede the structural changes (commonly seen as tumor shrinkage) and necrosis. Response assessment criteria have been developed on the basis of findings on FDG PET/CT images and are continuously being revised to ensure standardization and improve their predictive performance. Published under a CC BY 4.0 license. Quiz questions for this article are available through the Online Learning Center.

Post COVID-19 syndrome with impairment of flow-mediated epicardial vasodilation and flow reserve.

AIMS: The aim of this study is to evaluate whether post-acute sequelae of COVID-19 cardiovascular syndrome (PASC-CVS) is associated with alterations in coronary circulatory function. MATERIALS AND METHODS: In individuals with PASC-CVS but without known cardiovascular risk factors (n = 23) and in healthy controls (CON, n = 23), myocardial blood flow (MBF) was assessed with 13 N-ammonia and PET/CT in mL/g/min during regadenoson-stimulated hyperemia, at rest, and the global myocardial flow reserve (MFR) was calculated. MBF was also measured in the mid and mid-distal myocardium of the left ventricle (LV). The Δ longitudinal MBF gradient (hyperemia minus rest) as a reflection of an impairment of flow-mediated epicardial vasodilation, was calculated. RESULTS: Resting MBF was significantly higher in PASC-CVS than in CON (1.29 ± 0.27 vs. 1.08 ± 0.20 ml/g/min, p ≤ .024), while hyperemic MBFs did not differ significantly among groups (2.46 ± 0.53 and 2.40 ± 0.34 ml/g/min, p = .621). The MFR was significantly less in PASC-CVS than in CON (1.97 ± 0.54 vs. 2.27 ± 0.43, p ≤ .031). In addition, there was a Δ longitudinal MBF gradient in PASC-CVS, not observed in CON (-0.17 ± 0.18 vs. 0.04 ± 0.11 ml/g/min, p < .0001). CONCLUSIONS: Post-acute sequelae of COVID-19 cardiovascular syndrome may be associated with an impairment of flow-mediated epicardial vasodilation, while reductions in coronary vasodilator capacity appear predominantly related to increases in resting flow in women deserving further investigations.

Coronary circulatory function with increasing obesity: A complex U-turn.

AIMS: The aim of this investigation was to explore and characterize alterations in coronary circulatory function in function of increasing body weight with medically controlled cardiovascular risk factors and, thus, "metabolically" unhealthy obesity. MATERIALS AND METHODS: We prospectively enrolled 106 patients with suspected CAD but with normal stress-rest myocardial perfusion on 13 N-ammonia PET/CT and with medically controlled or no cardiovascular risk factors. 13 N-ammonia PET/CT concurrently determined myocardial blood flow (MBF) during pharmacologically induced hyperaemia and at rest. Based on body mass index (BMI), patients were grouped into normal weight (BMI: 20.0-24.9 kg/m2 , n = 22), overweight (BMI: 25.0-29.9 kg/m2 , n = 27), obese (BMI: 30.0-39.9 kg/m2 , n = 31), and morbidly obese (BMI ≥ 40kg/m2 , n = 26). RESULTS: Resting MBF was comparable among groups (1.09 ± 0.18 vs. 1.00 ± 0.15 vs. 0.96 ± 0.18 vs.. 1.06 ± 0.31 ml/g/min; p = .279 by ANOVA). Compared to normal weight individuals, the hyperaemic MBF progressively decreased in in overweight and obese groups, respectively (2.54 ± 0.48 vs. 2.02 ± 0.27 and 1.75 ± 0.39 ml/g/min; p < .0001), while it increased again in the group of morbidly obese individuals comparable to normal weight (2.44 ± 0.41 vs. 2.54 ± 0.48 ml/g/min, p = .192). The BMI of the study population correlated with the hyperaemic MBF in a quadratic or U-turn fashion (r = .34, SEE = 0.46; p ≤ .002). CONCLUSIONS: The U-turn of hyperaemic MBF from obesity to morbid obesity is likely to reflect contrasting effects of abdominal versus subcutaneous adipose tissue on coronary circulatory function indicative of two different disease entities, but needing further investigations.

Co-clinical FDG-PET radiomic signature in predicting response to neoadjuvant chemotherapy in triple-negative breast cancer.

PURPOSE: We sought to exploit the heterogeneity afforded by patient-derived tumor xenografts (PDX) to first, optimize and identify robust radiomic features to predict response to therapy in subtype-matched triple negative breast cancer (TNBC) PDX, and second, to implement PDX-optimized image features in a TNBC co-clinical study to predict response to therapy using machine learning (ML) algorithms. METHODS: TNBC patients and subtype-matched PDX were recruited into a co-clinical FDG-PET imaging trial to predict response to therapy. One hundred thirty-one imaging features were extracted from PDX and human-segmented tumors. Robust image features were identified based on reproducibility, cross-correlation, and volume independence. A rank importance of predictors using ReliefF was used to identify predictive radiomic features in the preclinical PDX trial in conjunction with ML algorithms: classification and regression tree (CART), Naïve Bayes (NB), and support vector machines (SVM). The top four PDX-optimized image features, defined as radiomic signatures (RadSig), from each task were then used to predict or assess response to therapy. Performance of RadSig in predicting/assessing response was compared to SUVmean, SUVmax, and lean body mass-normalized SULpeak measures. RESULTS: Sixty-four out of 131 preclinical imaging features were identified as robust. NB-RadSig performed highest in predicting and assessing response to therapy in the preclinical PDX trial. In the clinical study, the performance of SVM-RadSig and NB-RadSig to predict and assess response was practically identical and superior to SUVmean, SUVmax, and SULpeak measures. CONCLUSIONS: We optimized robust FDG-PET radiomic signatures (RadSig) to predict and assess response to therapy in the context of a co-clinical imaging trial.

FIGO 2018 staging criteria for cervical cancer: Impact on stage migration and survival.

OBJECTIVE: To compare FIGO 2009 and FIGO 2018 cervical cancer staging criteria with a focus on stage migration and treatment outcomes. METHODS: This study is based on a database cohort of 1282 patients newly diagnosed with cervical cancer from 1997 to 2019. All underwent standard clinical examination and whole-body FDG-PET. Tumor stage was recorded using the FIGO 2009 system, which excluded surgical pathologic, FDG-PET and other advanced imaging findings, and then re-classified to the FIGO 2018 system, including surgical pathologic and imaging findings. Patient management was based on clinical, surgical, and imaging findings. Stage migration and prognosis were evaluated. RESULTS: The distribution per the 2009 staging system was stage I in 593 (46%), stage II in 342 (27%), stage III in 263 (21%), and stage IV in 84 (7%) and the 2018 staging system was stage I in 354 (28%), stage II in 156 (12%), stage III in 601 (47%), and stage IV in 171 (13%). No patients were down-staged. Stage migration occurred in 53% (676/1282) and was attributable to detection of occult lymph node metastasis in 520 (41%), occult distant metastasis in 90 (7%), and tumor size and extent in 66 (5%). The 5-year progression-free survivals (PFS) by FIGO 2009 versus FIGO 2018 were as follows: stage I, 80% vs. 87% (p = 0.02); stage II, 59% vs. 71% (p = 0.002); stage III, 35% vs. 55% (p < 0.001), and stage IV, 20% vs. 16% (p = 0.41). CONCLUSION: Inclusion of surgical pathologic and imaging findings resulted in upward stage migration in the majority, mostly related to nodal and distant metastasis. While FIGO 2018 improves survival discriminatory ability for stages I and IV patients, survival remains heterogeneous among stage III substages.

Radiologic Assessment of Groin Lymph Nodes in Pelvic Malignancies.

INTRODUCTION: Metastatic involvement of groin nodes can alter radiation therapy planning for pelvic tumors. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) can identify nodal metastases; however, interpretation of PET/CT-positive nodes can be complicated by non-malignant processes. We evaluated quantitative metrics as methods to identify groin metastases in patients with pelvic tumors by comparison with standard subjective interpretive criteria, with pathology as the reference standard. METHODS: We retrospectively identified patients with vulvar, vaginal, or anal cancers who underwent 18F-FDG PET/CT before pathologic evaluation of groin nodes between 2007 and 2017. Because patho-radiologic correlation was not possible for every node, one index node identified on imaging was selected for each groin. For each index node, standardized uptake value measurements, total lesion glycolysis, metabolic tumor volume, CT-based volume, and short and long axes were measured. Multivariate logistic regression was used to identify metrics predictive for pathologically positive groins and generate a probabilistic model. Area under the receiver-operating characteristic curves (AUCs) for the model were compared with clinical interpretation from the diagnostic report via a Wald's χ2 test. RESULTS: Of 55 patients identified for analysis, 75 groins had pathologic evaluation resulting in 75 index groin nodes for analysis with 35 groins pathologically positive for malignancy. Logistic regression identified mean standardized-uptake-value (50% threshold) and short-axis length as the most predictive imaging metrics for metastatic nodal involvement. The probabilistic model performed better at predicting pathologic involvement compared with standard clinical interpretation on analysis (AUC 0.91, 95% CI 0.84 to 0.97 vs 0.80, 95% CI 0.71 to 0.89; p<0.01). DISCUSSION: Accuracy of 18F-FDG PET/CT for detecting groin nodal metastases in patients with pelvic tumors may be improved with the use of quantitative metrics. Improving prediction of nodal metastases can aid with appropriate selection of patients for pathologic node evaluation and guide radiation volumes and doses.

Detection of distant metastatic disease by positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) at initial staging of cervical carcinoma.

OBJECTIVE: The detection of distant metastatic disease in cervical cancer patients at diagnosis is critical in accurate prognostication and directing treatment strategies. This study describes the frequency and sites of distant metastatic disease at diagnosis in patients with cervical cancer as detected by positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET). METHODS: Patients with newly diagnosed cervical cancer underwent pre-treatment whole-body FDG-PET starting in 1997 at an academic institution. Patients with evidence of distant FDG-avid disease, defined as disease outside of typical sites of lymphatic spread, were included for analyses. Patients were not surgically staged, but biopsy to confirm metastatic disease was attempted at the discretion of the treating physicians. Overall survival was calculated using Kaplan-Meier analysis. RESULTS: From 1997 to 2017, 72 (6.2%) of 1158 consecutively evaluated cervical cancer patients exhibited FDG-avid distant disease at diagnosis; 27 (38%) of these had biopsy confirmation of distant disease. Only 35 (49%) of FDG-detected metastases were clinically apparent. The sites of distant disease were lung (35%), multiple sites (25%), omentum (16.5%), bone (16.5%), and liver (7%). There were 12 (17%) patients with distant disease who did not display FDG-avid lymph nodes. Median overall survival among patients with distant FDG-avid disease was 7.0 months (95% CI 4.3 to 9.7). Patients with multiple sites of distant disease demonstrated the worst overall survival. CONCLUSIONS: Distant metastatic disease detected by FDG-PET is found in 6.2% of patients with cervical cancer at the time of initial diagnosis and the most common site of disease is the lung. Further prospective investigation is warranted to delineate best treatment practices for cervical cancer patients presenting with distant metastases.

Impact of tumor histology on detection of pelvic and para-aortic nodal metastasis with 18F-fluorodeoxyglucose-positron emission tomography in stage IB cervical cancer.

OBJECTIVE: 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) detection of metastatic nodal disease is useful for guiding cervical cancer treatment but the impact of tumor histology is unknown. This study reports the detection of FDG avid pelvic and para-aortic lymph nodes in patients with early stage cervical cancer with squamous carcinoma and adenocarcinoma tumor histology. METHODS: Patients with International Federation of Gynecology and Obstetrics (FIGO) 2009 stage IB1-2 cervical cancer who underwent pre-surgical FDG-PET between March 1999 and February 2018 were identified in a tertiary academic center database. All patients had radical hysterectomy with pelvic and para-aortic lymph node dissection. Detection of pelvic and para-aortic lymph nodes by FDG-PET versus surgical dissection was compared. FDG-PET sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were determined and stratified by tumor histology. RESULTS: We identified 212 patients with early stage cervical cancer (84% FIGO IB1, 16% IB2) who underwent pre-surgical FDG-PET; 137 (65%) patients had squamous carcinoma and 75 (35%) patients had adenocarcinoma. PET/computed tomography was performed in 189 (89%) patients and 23 (11%) had PET only. Surgical dissection revealed positive pelvic and para-aortic lymph nodes in 25% and 3.3% of patients, respectively. For squamous carcinoma, sensitivity, specificity, PPV, and NPV of FDG-PET for pelvic nodal metastasis were 44%, 99%, 95%, and 78%, respectively. For adenocarcinoma, the corresponding results for pelvic nodal metastasis were 25%, 99%, 67%, and 92%, respectively. The overall values for sensitivity, specificity, PPV, and NPV of FDG-PET for para-aortic nodal metastasis were 29%, 99%, 67%, and 98%, respectively. DISCUSSION: Pelvic nodal metastasis was less likely to be detected by FDG-PET in patients with early stage adenocarcinoma than with squamous carcinoma.

Pazopanib plus cetuximab in recurrent or metastatic head and neck squamous cell carcinoma: an open-label, phase 1b and expansion study.

BACKGROUND: Angiogenesis is a hallmark of head and neck squamous cell carcinoma (HNSCC), and a mechanism of resistance to EGFR inhibition. We investigated the safety and potential activity of pazopanib, an angiogenesis inhibitor, plus cetuximab, an EGFR inhibitor, in patients with recurrent or metastatic HNSCC. METHODS: We did an open-label, single-centre, dose-escalation phase 1b trial using a standard 3 + 3 design, followed by an expansion cohort phase. Eligible participants were patients with histologically or cytologically confirmed recurrent or metastatic HNSCC, aged at least 18 years, had measurable disease as per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, and an Eastern Cooperative Oncology Group performance status of 0-1. During dose escalation, pazopanib oral suspension was administered daily in 8-week cycles at doses of 200 mg/day, 400 mg/day, 600 mg/day, or 800 mg/day, with cetuximab given intravenously once per week (400 mg/m2 first dose and 250 mg/m2 in consecutive cycles). The primary endpoint was to determine the maximum tolerated dose or recommended phase 2 dose of pazopanib in combination with cetuximab. Analyses were done per protocol. This trial is registered with ClinicalTrials.gov, number NCT01716416, and it is ongoing but closed to accrual. FINDINGS: Between June 5, 2013, and April 4, 2017, we enrolled 22 patients into the phase 1b, dose-escalation phase of the trial. A maximum tolerated dose of pazopanib in combination with cetuximab was not reached. Single dose-limiting toxic events (all grade 3) during dose escalation occurred with pazopanib 400 mg/day (neutropenia with infection), 600 mg/day (proteinuria), and 800 mg/day (fatigue). The established recommended phase 2 dose for the combination was 800 mg/day of pazopanib during cycles of 8 weeks each, plus cetuximab 400 mg/m2 on day 1 of cycle 1, then cetuximab 250 mg/m2 weekly. A further nine patients were enrolled into the expansion cohort and treated with the established recommended phase 2 dose. The most common (grade 3-4) adverse events for all patients were hypertension (ten [32%] of 31), lymphocyte count decrease (seven [23%]), and dysphagia (seven [23%]). There were no treatment-related deaths. 11 (35%; 95% CI 19·2-54·6) of 31 patients achieved an overall response, as assessed by the investigator; two (6%) had a complete response and nine (29%) a partial response. Tumour responses were also observed in six (55%) of 11 patients with platinum-naive and cetuximab-naive disease, three (25%) of 12 patients with cetuximab-resistant disease, and five (28%) of 18 patients with platinum-resistant disease. INTERPRETATION: Pazopanib oral suspension at a dose of 800 mg/day was feasible to administer in combination with standard weekly cetuximab for patients with recurrent or metastatic HNSCC. Encouraging preliminary antitumour activity was observed with this combination therapy and warrants further validation in randomised trials. FUNDING: GlaxoSmithKline and Novartis.

Serum squamous cell carcinoma antigen as an early indicator of response during therapy of cervical cancer.

BACKGROUND: Pretreatment serum squamous cell carcinoma antigen (SCCA) is a prognostic biomarker in women with cervical cancer. SCCA has not been evaluated as an early indicator of response to chemoradiation therapy (CRT). The molecular role of the two SCCA isoforms, SCCA1 (SERPINB3) and SCCA2 (SERPINB4), in cervical cancer is unknown. We hypothesised that changes in serum SCCA during definitive CRT predicts treatment response, and that SCCA1 mediates radiation resistance. METHODS: Patients treated with definitive CRT for cervical squamous carcinoma with serum SCCA measured were included. SCCA immunohistochemistry was performed on tumour biopsies. Post-treatment FDG-PET/CT, recurrence, and overall survival were recorded. Radiation response of cervical tumour cell lines after SCCA1 expression or CRISPR/Cas9 knockout was evaluated by clonogenic survival assay. RESULTS: Persistently elevated serum SCCA during definitive CRT was an independent predictor of positive post-therapy FDG-PET/CT (P=0.043), recurrence (P=0.0046) and death (P=0.015). An SCCA1-expressing vector increased radioresistance, while SCCA knock out increased radiosensitivity of cervical tumour cell lines in vitro. CONCLUSIONS: Early response assessment with serum SCCA is a powerful prognostic tool. These findings suggest that escalation of therapy in patients with elevated or sustained serum SCCA and molecular targeting of SCCA1 should be considered.

Evaluation of [89Zr]trastuzumab-PET/CT in differentiating HER2-positive from HER2-negative breast cancer.

PURPOSE: To evaluate whether tumor uptake of [89Zr]trastuzumab can distinguish HER2-positive from HER2-negative breast cancer. METHODS: Women with HER2-positive (n = 34) and HER2-negative (n = 16) breast cancer underwent PET/CT 5 ± 2 days following [89Zr]trastuzumab administration. HER2 status was determined based on immunohistochemistry and/or fluorescence in situ hybridization of primary or metastatic/recurrent tumor. Tumor [89Zr]trastuzumab uptake was assessed qualitatively and semiquantitatively as maximum standardized uptake value (SUVmax), and correlated with HER2 status. Additionally, intrapatient heterogeneity of [89Zr]trastuzumab uptake was evaluated. RESULTS: On a per-patient basis, [89Zr]trastuzumab-PET/CT was positive in 30/34 (88.2%) HER2-positive and negative in 15/16 (93.7%) HER2-negative patients. Considering all lesions, the SUVmax was not significantly different in patients with HER2-positive versus HER2-negative disease (p = 0.06). The same was true of when only hepatic lesions were evaluated (p = 0.42). However, after excluding hepatic lesions, tumor SUVmax was significantly higher in HER2-positive compared to HER2-negative patients (p = 0.003). A cutoff SUVmax of 3.2, determined by ROC analysis, demonstrated positive-predictive value of 83.3% (95% CI 65.3%, 94.4%), sensitivity of 75.8% (57.7%, 88.9%), negative-predictive value of 50% (24.7%, 75.3%), and specificity of 61.5% (95% 31.6%, 86.1%) for differentiating HER2-positive from HER2-negative lesions. There was intrapatient heterogeneity of [89Zr]trastuzumab uptake in 20% of patients with multiple lesions. CONCLUSIONS: [89Zr]trastuzumab has the potential to characterize the HER2 status of the complete tumor burden in patients with breast cancer, thus obviating repeat or multiple tissue sampling to assess intrapatient heterogeneity of HER2 status.

First-in-Man Evaluation of 124I-PGN650: A PET Tracer for Detecting Phosphatidylserine as a Biomarker of the Solid Tumor Microenvironment.

PURPOSE: PGN650 is a F(ab')2 antibody fragment that targets phosphatidylserine (PS), a marker normally absent that becomes exposed on tumor cells and tumor vasculature in response to oxidative stress and increases in response to therapy. PGN650 was labeled with 124I to create a positron emission tomography (PET) agent as an in vivo biomarker for tumor microenvironment and response to therapy. In this phase 0 study, we evaluated the pharmacokinetics, safety, radiation dosimetry, and tumor targeting of this tracer in a cohort of patients with cancer. METHODS: Eleven patients with known solid tumors received approximately 140 MBq (3.8 mCi) 124I-PGN650 intravenously and underwent positron emission tomography-computed tomography (PET/CT) approximately 1 hour, 3 hours, and either 24 hours or 48 hours later to establish tracer kinetics for the purpose of calculating radiation dosimetry (from integration of the organ time-activity curves and OLINDA/EXM using the adult male and female models). RESULTS: Known tumor foci demonstrated mildly increased uptake, with the highest activity at the latest imaging time. There were no unexpected adverse events. The liver was the organ receiving the highest radiation dose (0.77 mGy/MBq); the effective dose was 0.41 mSv/MBq. CONCLUSION: Although 124I-PGN650 is safe for human PET imaging, the tumor targeting with this agent in patients was less than previously observed in animal studies.

Utility of PET/CT to Evaluate Retroperitoneal Lymph Node Metastasis in High-Risk Endometrial Cancer: Results of ACRIN 6671/GOG 0233 Trial.

Purpose To assess the diagnostic accuracy of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with diagnostic contrast material-enhanced computed tomography (CT) in detecting lymph node (LN) metastasis in high-risk endometrial cancer. Materials and Methods This prospective multicenter HIPAA-compliant study had institutional review board approval, and all participants gave written informed consent. Data were accrued between January 2010 and June 2013. Patients underwent PET/CT and pelvic and abdominal lymphadenectomy. Two hundred seven of 215 enrolled patients had PET/CT and pathologic examination results for the abdomen and pelvis. Mean patient age was 62.7 years ± 9.6 (standard deviation). Data in all 23 patients with a positive abdominal examination and in 26 randomly selected patients with a negative abdominal examination were used for this central reader study. Seven independent blinded readers reviewed diagnostic CT and PET/CT results in different sessions 1 month apart. Accuracy was calculated at the participant level, correlating abdominal (right and left para-aortic and common iliac) and pelvic (right and left external iliac and obturator) LN regions with pathologic results, respecting laterality. Reader-average sensitivities, specificities, and areas under the receiver operating characteristic curve (AUCs) of PET/CT and diagnostic CT were compared. Power calculation was for sensitivity and specificity in the abdomen. Results Sensitivities of PET/CT versus diagnostic CT for the detection of LN metastasis were 0.65 (95% confidence interval [CI]: 0.57, 0.72) versus 0.50 (95% CI: 0.43, 0.58) (P = .01) in the abdomen and 0.65 (95% CI: 0.57, 0.72) versus 0.48 (95% CI: 0.41, 0.56) (P = .004) in the pelvis. Corresponding specificities were 0.88 (95% CI: 0.83, 0.92) versus 0.93 (95% CI: 0.89, 0.96) (P = .11) and 0.93 (95% CI: 0.86, 0.96) versus 0.89 (95% CI: 0.82, 0.94) (P = .27), and AUCs were 0.78 (95% CI: 0.66, 0.89) versus 0.74 (95% CI: 0.63, 0.86) (P = .39) and 0.82 (95% CI: 0.71, 0.92) versus 0.73 (95% CI: 0.63, 0.84) (P = .02). Conclusion FDG PET/CT has satisfactory diagnostic accuracy in the detection of abdominal LN metastasis in high-risk endometrial cancer. Compared with diagnostic CT alone, addition of PET to diagnostic CT significantly increased sensitivity in both the abdomen and pelvis while maintaining high specificity. © RSNA, 2017 Online supplemental material is available for this article.

Clinical application of PET/MRI in oncology.

Hybrid imaging with integrated positron emission tomography (PET) and magnetic resonance imaging (MRI) combines the advantages of the high-resolution anatomic data from MRI and functional imaging data from PET, and has the potential to improve the diagnostic evaluation of various types of cancers. The clinical oncologic applications of this newest hybrid imaging technology are evolving and substantial efforts are underway to define the role of PET/MRI in routine clinical use. The current published literature suggests that PET/MRI may play an important role in the evaluation of patients with certain types of malignancies, involving anatomic locations such as the pelvis and the liver. The purpose of this article is to review the current published PET/MRI literature in specific body oncologic applications. In addition, PET/MRI protocols and some of the technical issues of this hybrid imaging will be briefly discussed. J. Magn. Reson. Imaging 2016;44:265-276.

Utility of PET-CT to evaluate retroperitoneal lymph node metastasis in advanced cervical cancer: Results of ACRIN6671/GOG0233 trial.

OBJECTIVE: To assess if FDG PET combined with diagnostic CT improves diagnostic CT accuracy to detect lymph node (LN) metastasis in advanced cervical cancer. METHODS: A prospective HIPAA compliant ACRIN/GOG multicenter trial was conducted. Patients underwent concurrent diagnostic contrast-enhanced CT (DCT) and PET and pelvic/abdominal lymphadenectomy. Seven independent blinded readers reviewed PET-DCT and DCT one-month apart. Reference standard was surgically removed LN pathology. Accuracy values were calculated at participant level, correlating abdominal (right and left para-aortic/common iliac) and pelvic (right and left external iliac/obturator) LN regions with pathology, respecting laterality. Reader average sensitivities/specificities of PET-DCT vs. DCT were compared with generalized linear mixed models, and AUCs with Obuchowski's method. RESULTS: One hundred fifty-three patients had PET-DCT and pathology. Forty-three of 153 patients had metastasis to abdominal LNs. Sample size calculation required review of the first 40 abdominal positive and 40 randomly selected abdominal negative studies. Patients were 24 to 74years (48.9±10.6) old. Mean sensitivities of PET-DCT/DCT for detection of LN metastasis in abdomen were 0.50 (CI: 0.44, 0.56) and 0.42 (CI: 0.36, 0.48) (p=0.052) and in pelvis 0.83 (CI: 0.78, 0.87) and 0.79 (CI: 0.73, 0.83) (p=0.15). Corresponding specificities were 0.85 (CI: 0.80, 0.89) and 0.89 (CI: 0.84, 0.92) (p=0.21) and 0.63 (CI: 0.54, 0.70) and 0.62 (CI: 0.53, 0.69) (p=0.83). Mean AUC values were 0.70 (CI: 0.61, 0.79) and 0.68 (CI: 0.59, 0.77) (p=0.43) and 0.80 (CI: 0.71, 0.88) and 0.76 (CI: 0.67, 0.85) (p=0.21) respectively. CONCLUSION: Addition of PET to DCT resulted in statistically borderline increase in sensitivity to detect LN metastasis in abdomen in advanced cervical cancer.

[(18)F]FHBG PET/CT Imaging of CD34-TK75 Transduced Donor T Cells in Relapsed Allogeneic Stem Cell Transplant Patients: Safety and Feasibility.

Described herein is a first-in-man attempt to both genetically modify T cells with an imagable suicide gene and track these transduced donor T cells in allogeneic stem cell transplantation recipients using noninvasive positron emission tomography/computerized tomography (PET/CT) imaging. A suicide gene encoding a human CD34-Herpes Simplex Virus-1-thymidine kinase (CD34-TK75) fusion enabled enrichment of retrovirally transduced T cells (TdT), control of graft-versus-host disease and imaging of TdT migration and expansion in vivo in mice and man. Analysis confirmed that CD34-TK75-enriched TdT contained no replication competent γ-retrovirus, were sensitive to ganciclovir, and displayed characteristic retroviral insertion sites (by targeted sequencing). Affinity-purified CD34-TK75(+)-selected donor T cells (1.0-13 × 10(5))/kg were infused into eight patients who relapsed after allogeneic stem cell transplantation. Six patients also were administered 9-[4-((18)F)fluoro-3-hydroxymethyl-butyl]guanine ([(18)F]FHBG) to specifically track the genetically modified donor T cells by PET/CT at several time points after infusion. All patients were assessed for graft-versus-host disease, response to ganciclovir, circulating TdT cells (using both quantitative polymerase chain reaction and [(18)F]FHBG PET/CT imaging), TdT cell clonal expansion, and immune response to the TdT. This phase 1 trial demonstrated that genetically modified T cells and [(18)F]FHBG can be safely infused in patients with relapsed hematologic malignancies after allogeneic stem cell transplantation.

PET/MRI for the body imager: abdominal and pelvic oncologic applications.

The purpose of this pictorial review is to describe emerging clinical applications of positron emission tomography (PET)/magnetic resonance imaging (MRI), the newest clinical hybrid imaging modality, with a specific focus on abdominal and pelvic malignancies. Important issues regarding the clinical implementation of PET/MRI systems, including workflow considerations and protocol development, are examined. The unique technical challenges of simultaneous PET/MRI acquisition and MRI-based attenuation correction are also briefly discussed. This article is intended to provide the body imager with an overview of the potential diagnostic advantages of PET/MRI, as compared to PET/CT or MRI alone.

Diffusion-weighted MRI for staging and evaluation of response in diffuse large B-cell lymphoma: a pilot study.

The aim of this study was to compare diffusion-weighted MRI (DW-MRI) with positron emission tomography/computed tomography (PET/CT) for the staging and evaluation of the treatment response in patients with diffuse large B-cell lymphoma (DLBCL). Institutional review board approval was obtained for this study; all subjects gave informed consent. Twelve patients were imaged before treatment and eight of these were also imaged after two cycles of chemotherapy using both DW-MRI and PET/CT. Up to six target lesions were selected at baseline for response assessment based on International Working Group criteria (nodes > 1.5 cm in diameter; extranodal lesions > 1 cm in diameter). For pretreatment staging, visual analysis of the numbers of nodal and extranodal lesions based on PET/CT was performed. For interim response assessment after cycle 2 of chemotherapy, residual tumor sites were assessed visually and the percentage changes in target lesion size, maximum standardized uptake value (SUVmax ) and apparent diffusion coefficient (ADC) from pretreatment values were calculated. In 12 patients studied pretreatment, there were 46 nodal and 16 extranodal sites of lymphomatous involvement. Agreement between DW-MRI and PET/CT for overall lesion detection was 97% (60/62 tumor sites; 44/46 nodal and 16/16 extranodal lesions) and, for Ann Arbor stage, it was 100%. In the eight patients who had interim assessment, five of their 49 tumor sites remained abnormal on visual analysis of both DW-MRI and PET/CT, and there was one false positive on DW-MRI. Of their 24 target lesions, the mean pretreatment ADC value, tumor size and SUVmax were 772 µm(2) /s, 21.3 cm(2) and 16.9 g/mL, respectively. At interim assessment of the same 24 target lesions, ADC values increased by 85%, tumor size decreased by 74% and SUVmax decreased by 83% (all p < 0.01 versus baseline). DW-MRI provides results comparable with those of PET/CT for staging and early response assessment in patients with DLBCL.