A lesson in humility: the added values of PET-MRI over PET-CT in detecting malignant hepatic lesions.

PURPOSE: The recent introduction of integrated PET-MRI systems into practice seems promising in oncologic imaging, and efforts are made to specify their added values. The current study evaluates the added values of PET-MRI over PET-CT in detecting active malignant hepatic lesions. METHODS: As part of an ongoing prospective study in our institution that assesses the added values of PET-MRI, subjects undergo PET-CT and subsequent PET-MRI after single radiotracer injection. The current study included 97 pairs of whole-body PET-CT and liver PET-MRI scans, of 61 patients (19/61 had ≥ 2 paired scans), all performed with [18F]FDG and interpreted as showing active malignant hepatic involvement. Primary malignancies were of colorectal/biliary/pancreatic/breast/other origins in 19/9/9/7/17 patients. Monitoring response to therapy was the indication in 86/97 cases. When PET-MRI detected additional malignant lesions over PET-CT, lesions size, their characteristics on PET-MRI, and the influence on the final report were recorded. RESULTS: In 37/97 (38.1%) cases, a total of 78 malignant lesions were identified on PET-MRI but not on PET-CT: 19 lesions (11 cases) were identified on PET of PET-MRI but not on PET of PET-CT; 37 lesions (14 cases) were small (≤ 0.8 cm) and identified on MRI only; 22 lesions (12 cases) were > 0.8 cm, had low/no [18F]FDG uptake, but were categorized as viable based on MRI. These 78 lesions caused major effect on final reports in 11/97 (11.3%) cases, changing reported response assessment category (10/86 cases) or defining malignant hepatic disease on staging/restaging scans (1/11 cases). CONCLUSION: PET-MRI offers several advantages over PET-CT in assessing the extent and response to therapy of malignant hepatic involvement. Additional malignant lesions detected on PET-MRI are attributed to superior PET performance (compared with PET of PET-CT), greater spatial resolution provided by MRI, and improved multi-parametric viability assessment. In around one-tenth of cases, findings identified on PET-MRI but not on PET-CT significantly change the final report's conclusion.

PET radiotracers for whole-body in vivo molecular imaging of prostatic neuroendocrine malignancies.

Prostatic neuroendocrine malignancies represent a spectrum of diseases. Treatment-induced neuroendocrine differentiation (tiNED) in hormonally treated adenocarcinoma has been the subject of a large amount of recent research. However, the identification of neuroendocrine features in treatment-naïve prostatic tumor raises a differential diagnosis between prostatic adenocarcinoma with de novo neuroendocrine differentiation (dNED) versus one of the primary prostatic neuroendocrine tumors (P-NETs) and carcinomas (P-NECs). While [18F]FDG is being used as the main PET radiotracer in oncologic imaging and reflects cellular glucose metabolism, other molecules labeled with positron-emitting isotopes, mainly somatostatin-analogues labeled with 68Ga and prostate-specific membrane antigen (PSMA)-ligands labeled with either 18F or 68Ga, are now routinely used in departments of nuclear medicine and molecular imaging, and may be advantageous in imaging prostatic neuroendocrine malignancies. Still, the selection of the preferred PET radiotracer in such cases might be challenging. In the current review, we summarize and discuss published data on these different entities from clinical, biological, and molecular imaging standpoints. Specifically, we review the roles that [18F]FDG, radiolabeled somatostatin-analogues, and radiolabeled PSMA-ligands play in these entities in order to provide the reader with practical recommendations regarding the preferred PET radiotracers for imaging each entity. In cases of tiNED, we conclude that PSMA expression may be low and that [18F]FDG or radiolabeled somatostatin-analogues should be preferred for imaging. In cases of prostatic adenocarcinoma with dNED, we present data that support the superiority of radiolabeled PSMA-ligands. In cases of primary neuroendocrine malignancies, the use of [18F]FDG for imaging high-grade P-NECs and radiolabeled somatostatin-analogues for imaging well-differentiated P-NETs is recommended. KEY POINTS: • The preferred PET radiotracer for imaging prostatic neuroendocrine malignancies depends on the specific clinical scenario and pathologic data. • When neuroendocrine features result from hormonal therapy for prostate cancer, PET-CT should be performed with [18F]FDG or radiolabeled somatostatin-analogue rather than with radiolabeled PSMA-ligand. • When neuroendocrine features are evident in newly diagnosed prostate cancer, differentiating adenocarcinoma from primary neuroendocrine malignancy is challenging but crucial for selection of PET radiotracer and for clinical management.

Prognostic significance of delayed complete metabolic response on PET/CT after primary chemoradiation treatment of cervical cancer.

OBJECTIVE: To investigate the prognostic significance of near-complete metabolic response on initial follow-up PET/CT after primary chemoradiation treatment of cervical cancer. METHODS: Survival data were retrospectively compared between patients who had complete metabolic response on first follow-up PET/CT, 3 months after chemoradiation (group 1) with those who had near-complete metabolic response on first PET/CT and later showed complete metabolic response at subsequent PET/CT, 6 months or more after treatment (group 2). RESULTS: Of the 108 patients included in the final analysis, 74 (68.5%) showed complete metabolic response on initial PET/CT, 3 months after treatment, and 34 patients (31.5%) showed complete metabolic response on subsequent PET/CT, 6 months after treatment. Tumor characteristics were comparable between groups. Group 1 had higher percent of stage 1 (12% vs 0%) and lower percent of stage 4 disease (3% vs 14%) than those of group 2. Group 2 patients had significantly fewer cases of recurrences and deaths than group 1 patients (6% vs 26%, p=0.018; 0% vs 20%, p=0.003, respectively), with comparable 3-year survival rates (group 1, 90% vs group 2, 100%, p=0.31). Twelve patients had progressive disease on first follow-up PET/CT; these patients had significantly worse overall survival compared with all other patients (log-rank test, p<0.001). Younger age and delayed complete metabolic response were associated with lower chance of recurrence and death on univariate analysis. On multivariate analysis, delayed complete metabolic response remained significantly associated with no recurrence HR=0.14 (95% CI 0.25 to 0.84), p=0.031. CONCLUSIONS: Survival outcome of patients with cervical cancer who show residual 18F-fluorodeoxyglucose uptake on initial PET/CT after treatment, but reach complete metabolic response on follow-up PET/CT, is not inferior compared with survival of patients who show complete metabolic response on initial PET/CT 3 months after treatment. Watchful waiting with follow-up PET/CT seems a safe option for these patients.

Beyond Visual Assessment of Basal Ganglia Uptake: Can Automated Method and Pineal Body Uptake Assessment Improve Identification of Nigrostriatal Dysfunction on 18F-DOPA PET/CT?

The interpretation of 18F-DOPA PET/CT performed for assessing nigrostriatal dysfunction (NSD) is usually based on visual assessment of the uptake in the basal ganglia (VA-BG). In the present study, we evaluate the diagnostic performance of an automated method that assesses BG uptake (AM-BG) and of methods that assess pineal body uptake, and examine whether these methods can enhance the diagnostic performance of VA-BG alone. We retrospectively included 112 scans performed in patients with clinically suspected NSD who also had a subsequent final clinical diagnosis provided by a movement disorder specialist (69 NSD and 43 non-NSD patients). All scans were categorized as positive or negative based on (1) VA-BG, (2) AM-BG, and (3) qualitative and semiquantitative assessment of pineal body uptake. VA-BG, AM-BG, assessment of pineal body 18F-DOPA uptake by VA (uptake > background), by SUVmax (≥0.72), and by pineal to occipital ratio (POR ≥ 1.57) could all significantly differentiate NSD from non-NSD patients (Pv < 0.01 for all five methods). Of these methods, VA-BG provided the highest sensitivity (88.4%) and accuracy (90.2%). Combining VA-BG with AM-BG did not improve diagnostic accuracy. An interpretation algorithm that combines VA-BG with pineal body uptake assessment by POR calculation increased sensitivity to 98.5%, at the expense of decreased specificity. In conclusion, an automated method that assesses 18F-DOPA uptake in the BG and assessment of pineal body 18F-DOPA uptake can significantly separate NSD from non-NSD patients, with apparent inferior diagnostic performance when applied alone compared with VA-BG. When VA-BG categorizes a scan as negative or equivocal, assessment of the 18F-DOPA uptake in the pineal body has the potential to minimize the rate of false negative reports. Further research is essential to validate this approach and to study the pathophysiologic relationship between 18F-DOPA uptake in the pineal body and nigrostriatal dysfunction.

A sigh of relief: vaccine-associated hypermetabolic lymphadenopathy following the third COVID-19 vaccine dose is short in duration and uncommonly interferes with the interpretation of [18F]FDG PET-CT studies performed in oncologic patients.

PURPOSE: The incidence of COVID-19 vaccine-associated hypermetabolic lymphadenopathy (VAHL) is high following the administration of the first and second BNT162b2 vaccine doses. The impact of this finding on [18F]FDG PET-CT interpretation and its correlation with the induced humoral immunity have been reported. Assuming the amnestic immune response is different following the third vaccine dose, we aimed to explore the incidence of VAHL over time after the third BNT162b2 dose administration, and its relevance to [18F]FDG PET-CT interpretation in oncologic patients. METHODS: A total of 179 consecutive oncologic patients that underwent [18F]FDG PET-CT after a third BNT162b2 vaccine dose were included. The presence of VAHL was assessed. On VAHL-positive scans, the SUVmax, number, location, and size of the "hot" nodes were recorded. The median time interval between vaccination and imaging was 8 (IQR, 5-14) days. RESULTS: The incidences of all-grade VAHL and grade 3-4 VAHL were 47.5% and 8.9%, respectively. VAHL was identified on 82.5% of studies performed within the first 5 days from vaccination. Grade 3-4 VAHL was observed on 28.1% of studies performed within the first 5 days from vaccination, but was not detected on studies performed more than 5 days from vaccination. Separation between VAHL and malignant lymphadenopathy was not possible in only 2 of the 179 study patients. On a multivariable logistic regression, independent predictors of grade 3-4 VAHL were short time interval between vaccination and imaging (Pv < 0.01), younger age (Pv < 0.01), and lower BMI (Pv = 0.03). CONCLUSION: VAHL is commonly identified on [18F]FDG PET-CT performed within the first 5 days from the third BNT162b2 vaccine dose administration. High-grade VAHL is unlikely to be observed on a scan performed 6 days or longer from vaccination, and is even less likely in older and obese patients.

Head-to-head comparison of [68Ga]Ga-FAPI-04 and [18F]-FDG PET/CT in evaluating the extent of disease in gastric adenocarcinoma.

BACKGROUND: [18F]-Fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) may sometimes be suboptimal for imaging gastric adenocarcinoma. The recently introduced [68Ga]Ga-FAPI-04 (FAPI) PET/CT targets tumor stroma and has shown considerable potential in evaluating the extent of disease in a variety of tumors. METHODS: We performed a head-to-head prospective comparison of FAPI and FDG PET/CT in the same group of 13 patients with gastric adenocarcinoma who presented for either initial staging (n = 10) or restaging (n = 3) of disease. Lesion detection and maximum standardized uptake value (SUVmax) were compared between the two types of radiotracers. RESULTS: All ten primary gastric tumors were FAPI-positive (100% detection rate), whereas only five were also FDG-positive (50%). SUVmax was not significantly different, but the tumor-to-background ratio was higher for FAPI (mean, median, and range of 4.5, 3.2, and 0.8-9.7 for FDG and 12.9, 11.9, and 2.2-23.9 for FAPI, P = 0.007). The level of detection of regional lymph node involvement was comparable. FAPI showed a superior detection rate for peritoneal carcinomatosis (100% vs. none). Two patients with widespread peritoneal carcinomatosis underwent a follow-up FAPI scan after chemotherapy: one showed partial remission and the other showed progressive disease. CONCLUSIONS: The findings of this pilot study suggest that FAPI PET/CT outperforms FDG PET/CT in detecting both primary gastric adenocarcinoma and peritoneal carcinomatosis from gastric cancer. FAPI PET/CT also shows promise for monitoring response to treatment in patients with peritoneal carcinomatosis from gastric cancer; however, larger trials are needed to validate these preliminary findings.

Staging 68 Ga-PSMA PET/CT in 963 consecutive patients with newly diagnosed prostate cancer: incidence and characterization of skeletal involvement.

PURPOSE: The aim of the study was to elaborate the incidence and type of skeletal involvement in a large cohort of patients with newly diagnosed prostate cancer (PCa) referred for Ga-68 PSMA-11 PET/CT staging in a single center. METHODS: Study cohort included 963 consecutive patients with newly diagnosed PCa referred for Ga-68 PSMA-11 PET/CT study for staging. The incidence of bone involvement, type of bone metastases, and extent of disease were determined and correlated with the ISUP Grade Group (GG) criteria and PSA levels. RESULTS: Bone metastases were found in 188 (19.5%) of 963 patients. Bone metastases were found in 10.7% of patients with PSA < 10 ng/dL and in 27.4% of patients with PSA > 10 ng/dL and in 6.1% of patients with GG ≤ 2/3 and in 8.9% of patients with GG 4/5. In 7.6% of the patients, skeletal involvement was extensive, while 11.9% of patients had oligometastatic disease. Osteoblastic type metastases were the most common type of bone metastases presented in 133 of the patients with malignant bone involvement (70.7%). More than half of them had only osteoblastic lesions (72 patients (38.3%)), while the other (61 patients (32.5%)) had also intramedullary and/or osteolytic type lesions. Intramedullary metastases were found in 97 patients (51.6%), while 41 (21.8%) of them were only intramedullary lesions. Osteolytic metastases were detected in 36 patients (19.2%), of which 8 were only osteolytic lesions. CONCLUSION: Although traditionally bone metastases of PCa are considered osteoblastic, osteolytic and intramedullary metastases are common, as identified on PET with labeled PSMA. Skeletal spread may be present also in patients with GG ≤ 2/3 and PSA < 10 ng/dL.

[18F]FDG PET-CT in patients with DLBCL treated with CAR-T cell therapy: a practical approach of reporting pre- and post-treatment studies.

PURPOSE: The introduction of CD19-specific chimeric antigen receptor T-cell therapy (CAR-T) for treatment of relapsed/refractory diffuse large B cell lymphoma (R/R DLBCL) gives hope to patients with otherwise dismal prognosis. Therapy outcomes, however, depend upon selection of patients and accurate early identification of non-responders. Patients treated with CAR-T usually undergo [18F]FDG PET-CT at time of decision (TD), time of CAR-T transfusion (TT), 1 month (M1), and 3 months (M3) post-therapy. The purpose of the current study was to identify the specific parameters that should be addressed when reporting PET-CT studies in the clinical setting of CAR-T therapy. METHODS: A total of 138 PET-CT scans (30 TD, 42 TT, 44 M1, 22 M3) of 48 patients treated with CAR-T were included. SUVmax, TMTV, and TLG were calculated in all scans. Response was assessed using the Deauville scale and ΔSUVmax method. Overall survival (OS) was the primary endpoint. Median follow-up was 12.8 (IQR 6.4-16.0) months from CAR-T infusion. RESULTS: In a univariate analysis, TD-SUVmax > 17.1 and TT-SUVmax > 12.1 were associated with shorter OS (Pv < 0.05). In a multivariate analysis, three factors were significantly associated with shorter OS: TD-SUVmax > 17.1 (HR 10.3; Pv < 0.01), LDH > 450 U/l (HR 7.7; Pv < 0.01), and ECOG score > 1 (HR 5.5; Pv = 0.04). Data from TD and TT PET-CT scans were not predictive of toxicity. On M1-PET-CT, patients with a Deauville score > 3 had significantly shorter OS (median 7.9 months, versus not reached, Pv < 0.01). ΔSUVmax ≤ 66% on M1-PET-CT predicted shorter OS when M1-SUVmax was compared to TD-SUVmax (Pv = 0.02) but not to TT-SUVmax (Pv = 0.38). CONCLUSION: Pre-treatment SUVmax may guide patient selection for CAR-T therapy. On M1-PET-CT, Deauville score and ΔSUVmax from TD may identify early therapy failure. These parameters are easy to obtain and should be included in the PET-CT report.

Hypermetabolic lymphadenopathy following administration of BNT162b2 mRNA Covid-19 vaccine: incidence assessed by [18F]FDG PET-CT and relevance to study interpretation.

PURPOSE: Nationwide mass vaccination against Covid-19 started in Israel in late 2020. Soon we identified on [18F]FDG PET-CT studies vaccine-associated hypermetabolic lymphadenopathy (VAHL) in axillary or supraclavicular lymph nodes (ASLN) ipsilateral to the vaccination site. Sometimes, differentiation between the malignant and benign nature of the hypermetabolic lymphadenopathy (HLN) could not be made, and equivocal HLN (EqHL) was reported. The purpose of the study was to determine the overall incidence of VAHL after BNT162b2 vaccination and also its relevance to PET-CT interpretation in oncologic patients. METHODS: A total of 951 consecutive patients that underwent [18F]FDG PET-CT studies in our department were interviewed regarding the sites and dates of the vaccine doses. A total of 728 vaccinated patients (All-Vac group) were included: 346 received the first dose only (Vac-1 group) and 382 received the booster dose as well (Vac-2 group). Studies were categorized as no HLN, malignant-HLN (MHL), VAHL, or EqHL. In studies with VAHL, location, [18F]FDG-intensity uptake and nodes size were recorded. RESULTS: The incidences of HLN were 45.6%, 36.4%, and 53.9% in All-Vac, Vac-1, and Vac-2 groups, respectively. VAHL was reported in 80.1% of vaccinated patients with HLN. Lower incidences of VAHL were found during the first 5 days or in the third week after the first vaccine and beyond 20 days after the booster dose. In 49 of 332 (14.8%) vaccinated patients, we could not determine whether HLN was MHL or VAHL. Breast cancer and lymphoma were the leading diseases with EqHL. CONCLUSION: VAHL is frequently observed after BNT162b2 administration, more commonly and with higher intensity following the booster dose. To minimize false and equivocal reports in oncological patients, timing of [18F]FDG PET-CT should be based on the time intervals found to have a lower incidence of VAHL, and choice of vaccine injection site should be advised, mainly in patients where ASLN are a relevant site of tumor involvement.

Correlation between BNT162b2 mRNA Covid-19 vaccine-associated hypermetabolic lymphadenopathy and humoral immunity in patients with hematologic malignancy.

PURPOSE: Vaccine-associated hypermetabolic lymphadenopathy (VAHL) is frequently observed on [18F]FDG PET-CT following BNT162b2 administration. Recent data suggest a prominent B cell germinal-center (GC) response elicited by mRNA vaccines in draining lymph nodes. Thus, in this study we aimed to explore the correlation between VAHL and humoral immunity as reflected by post-vaccination serologic testing and by comparing the incidence of VAHL between lymphoma patients treated recently with B cell depleting therapy and those that were not. METHODS: A total of 137 patients with hematologic malignancy that had post-vaccination [18F]FDG PET-CT were included (All-PET group), 86 received both vaccine doses before imaging (PET-2 group). Their VAHL status and grade on imaging were recorded. Among 102 lymphoma patients, 34 (33.3%) were treated during the year prior vaccination with anti-CD20 antibody containing therapy. A subgroup of 54 patients also underwent serologic testing 2-3 weeks after the booster dose, and their anti-spike titers were recorded and graded as well. RESULTS: The overall incidence of VAHL in patients with hematologic malignancy was 31.4%. The 34 lymphoma patients treated during the year prior vaccination with anti-CD20 antibody containing therapy had significantly lower rates of VAHL comparted with all other lymphoma patients (8.8 versus 41.2% in all-PET patients, Pv < 0.01). VAHL rates were 10% in patients with negative serology, 31.3% in patients with low anti-spike titers, and 72.2% in patients with high anti-spike titers. The positive predictive values of VAHL were 90 and 93.3% in all-PET and PET-2 patients, respectively. A positive statistically significant correlation was found between VAHL and serology ranks in All-PET patients (rs = 0.530, Pv < 0.001), and stronger correlation was found in PET-2 patients (rs = 0.642, Pv < 0.001). CONCLUSION: VAHL on [18F]FDG PET-CT of patients with hematologic malignancy may reflect GC B cell proliferation and an effective humoral response elicited by BNT162b2 vaccine.

[METABOLIC AND DOPAMINERGIC BRAIN FUNCTIONAL IMAGING IN DEMENTIA WITH LEWY BODIES].

INTRODUCTION: Dementia with Lewy bodies (DLB) is the second most common neurodegenerative dementia of the elderly. Its early diagnosis is a clinical challenge due to overlapping symptoms of various neurodegenerative diseases. Early diagnosis is essential for patient management avoiding neuroleptic medications that harbor the risk of causing further deterioration. Functional imaging allows accurate diagnosis and improves the degree of confidence in the diagnosis. Its advantage is based on the ability to identify biochemical changes that precede structural changes, thereby providing valuable information at early stages of the disease. Another advantage is its ability to provide a non-invasive neurobiological evaluation as well as an objective follow-up algorithm. We present a patient with cognitive and motor decline, in which anatomical imaging (MRI) failed to recognize a specific morphological abnormality. Combined data of two PET-CT brain scans using two different radiotracers raised the diagnosis of DLB. Cortical metabolism was obtained by PET with labeled glucose (FDG) and the dopaminergic activity by labeled precursor (F-DOPA) of the neurotransmitter Dopamine. In times to come, with the development of novel specific tracers, diagnostic confidence is expected to improve, along with development of new approaches of therapy.

[THE ROLE OF PSMA PET/CT IN IMAGING PROSTATE CANCER].

INTRODUCTION: Accurate evaluation of the extent of disease in patients with prostate cancer is of great importance in guiding suitable treatment at all disease stages. Conventional imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), which rely on morphological criteria, are limited in assessing the real extent of prostate cancer. In recent years, molecular imaging via PET/CT using small molecules targeting the prostate-specific membrane antigen (PSMA) protein on prostate cancer cells linked to positron emitting isotopes has emerged as a promising diagnostic tool. PSMA PET/CT, with its high sensitivity and specificity, has revolutionized the field of prostate cancer imaging. The main indications for PSMA PET/CT imaging are staging of high-risk patients and evaluation of biochemical failure. In addition, PSMA-targeting particle-emitting radioligands allow targeted therapy in patients with advanced disease, with promising results.

[STAGING CERVICAL CANCER USING PET-CT AND PET-MRI].

INTRODUCTION: Whole-body Positron Emission Tomography-Computerized Tomography (PET-CT) and pelvic Magnetic Resonance (MR) imaging are included in developed countries in the imaging algorithm of newly diagnosed cervical cancer (CC). In recent years, the novel technology of PET-MR has been introduced in the clinical practice of tumor imaging. We present a patient with newly-diagnosed CC, who was evaluated using whole-body PET-CT and pelvic PET-MR in a single visit in our department. The role of the latter technologies in defining the anatomical, metabolic and functional data for optimal staging of CC is illustrated. We review the advantages and limitations of each of the modalities in staging the primary, nodal and distant disease, discuss the importance of accurate staging for guiding clinical management, and highlight the unique benefit of PET-MR in imaging of CC.

[18F] FDOPA PET may confirm the clinical diagnosis of Parkinson's disease by imaging the nigro-striatal pathway and the sympathetic cardiac innervation: Proof-of-concept study.

Autonomic involvement, including cardiac denervation, may precede the motor symptoms of Parkinson's disease by several years. L-3,4-dihydroxy-6-[18F] fluoro-phenylalanine is a positron emitter and a true analog of L-dopa, used in clinical practice to assess striatal dopaminergic integrity. The present study aimed to assess the feasibility of evaluating cardiac sympathetic denervation in Parkinson's disease patients using L-3,4-dihydroxy-6-[18F] fluoro-phenylalanine positron emission tomography/computed tomography. Patients referred for an L-3,4-dihydroxy-6-[18F] fluoro-phenylalanine positron emission tomography/computed-tomography between July 2015 and May 2017 to evaluate striatal presynaptic dopaminergic integrity underwent a heart positron emission tomography scan following a brain positron emission tomography scan. L-3,4-dihydroxy-6-[18F] fluoro-phenylalanine uptake in the left ventricle was quantified using CarimasT⁢M software and compared between patients with and without Parkinson's disease. The area under the receiver operating characteristic curve was used to evaluate the ability of the left ventricular mean standardized uptake value to discriminate between patients with Parkinson's disease and those with other extrapyramidal syndromes. Seventy-six patients were included, of whom 52 were diagnosed with Parkinson's disease. The mean L-3,4-dihydroxy-6-[18F] fluoro-phenylalanine left ventricular mean standardized uptake value was lower in the Parkinson's disease patients compared to the non- Parkinson's disease patients (1.08 ± 0.21 vs. 1.24 ± 0.32, P = 0.015). The left ventricular mean standardized uptake value was able to discriminate between Parkinson's disease and non- Parkinson's disease patients (the area under the receiver operating characteristic curve = 0.641, P = 0.049). In conclusion, quantification of cardiac L-3,4-dihydroxy-6-[18F] fluoro-phenylalanine uptake may be able to differentiate between patients with and without Parkinson's disease. Validation of this finding in more substantial, prospective trials are warranted.

Ga-PSMA PET/CT Staging of Newly Diagnosed Intermediate- and High-Risk Prostate Cancer.

BACKGROUND: Ga-prostate-specific membrane antigen positron emission tomography/computerized tomography (Ga-PSMA PET/CT) is part of the initial workup of patients with intermediate and high-risk prostate cancer provided by the Israeli national health services. OBJECTIVES: To assess the incidence of metastatic spread in consecutive patients with newly diagnosed cancer, and the potential added value of Ga-PSMA PET/CT to the staging imaging algorithm. METHODS: Patients with newly diagnosed intermediate- and high-risk prostate cancer were referred for initial staging by Ga-PSMA PET/CT between May 2016 and April 2017. Blood prostate-specific antigen (PSA) levels, clinical history, imaging reports and histopathological reports (including Gleason scores) were obtained. Maximal standardized uptake values (SUVmax) were determined for the primary lesions detected within the prostate. RESULTS: The study included 137 consecutive patients with intermediate- and high-risk disease who underwent Ga-PSMA PET/CT staging. Of these, 75 had Ga-PSMA uptake in both prostate lobes, 57 had unilateral uptake, and 5 patients had no uptake. SUVmax in the primary tumor correlated significantly with PSA levels. Thirty-five patients had increased uptake compatible with metastatic disease involving lymph nodes, bone, and viscera. Twenty-seven patients had available bone scintigraphy results: 18 (69%) of their 26 bone metastases detected by Ga-PSMA PET/CT were missed on bone scintigraphy. CONCLUSIONS: Ga-PSMA PET/CT shows promise as a sole whole-body imaging modality for assessing the presence of soft tissue and bone metastases in the setting of prostate cancer.

The Utility of 18F-fluorodeoxyglucose Positron-Emission Tomography/Computed Tomography in Cutaneous B-Cell Lymphoma.

BACKGROUND: Whole-body integrated positron emission tomography / contrast-enhanced computed tomography (PET/CT) scan is increasingly used in cutaneous lymphomas. However, the value of PET/CT in the detection of cutaneous lesions in primary cutaneous B-cell lymphoma (PCBCL) has barely been investigated. OBJECTIVES: To investigate the diagnostic accuracy of PET/CT in tracking cutaneous involvement in PCBCL. METHODS: A retrospective study was conducted on 35 consecutive patients diagnosed with cutaneous B-cell lymphoma according to the World Health Organization classification who were evaluated with PET/CT as the initial staging procedure before treatment. RESULTS: Thirty-five patients met the study criteria. In two patients extracutaneous disease was detected by PET/CT and CT and confirmed by biopsy. Of the 33 patients with PCBCL, 26 (79%) had small cell PCBCL (18 marginal-zone, 8 follicle-center lymphoma) and 7 (21%) had large cell PCBCL (3 follicle-center, 3 leg-type, 1 indeterminate). PET/CT detected skin lesions in 3 of 26 patients (12%) with small-cell PCBCL as compared to 6 of 7 patients with large-cell PCBLC (86%), a 7.4-fold detection risk (95% confidence interval, 2.4-22, P = 0.004). The PET-positive subgroup was characterized by larger lesion size (P < 0.001) and a higher Ki-67 proliferation index (P < 0.001). CONCLUSIONS: The sensitivity of PET/CT for detecting cutaneous involvement of lymphomas is low for small-cell PCBCL but high for large-cell types, and thus may facilitate therapeutic strategies.

[18F]fludeoxyglucose positron emission tomography and computed tomography as a prognostic tool before liver transplantation, resection, and loco-ablative therapies for hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third most common cause of cancer-related death worldwide. Orthotopic liver transplantation (OLT) and resection are curative treatment options for well-selected patients with HCC, whereas loco-ablative therapy has been shown to prolong survival. Organ and treatment allocations for these patients are currently based on the number and size of tumors, as defined by the Milan criteria, and on functional capacity, and they are incorporated into the Barcelona Clinic Liver Cancer staging system and treatment strategy. Even though these staging criteria have markedly improved the outcomes of patients with HCC, they still lack accuracy in predicting the risk of tumor recurrence because they do not incorporate markers of tumor biology and behavior. Positron emission tomography (PET) and computed tomography (CT) with [(18) F]fludeoxyglucose ([(18) F]FDG) constitute an imaging modality for detecting tumor tissue that is metabolically active. Uptake of [(18) F]FDG is highly associated with tumor aggressiveness. In this review, we present the accumulating data on the use of [(18) F]FDG PET-CT as an in vivo biomarker and its predictive value in identifying patients at risk for HCC recurrence after liver transplantation, resection, or ablation. These data suggest that the introduction of [(18) F]FDG PET-CT into the imaging algorithm of patients planned for liver transplantation, resection, or ablation may improve outcomes.

Staging Prostate Cancer with 68Ga-PSMA-11 PET/CT in the Elderly: Is Preimaging Biopsy Imperative?

Although prostate-specific membrane antigen (PSMA) PET/CT has been shown valuable for staging biopsy-proven [B(+)] high-risk prostate cancer, elderly patients are occasionally referred for PSMA PET/CT without a preimaging confirming biopsy [B(-)]. The current study evaluated the rate, clinical characteristics, and PET-based stage of elderly B(-) patients and explored whether biopsy status affects therapeutic approach. Methods: One hundred consecutive patients at least 80 y old who underwent staging 68Ga-PSMA-11 PET/CT were included. For each patient, we documented whether preimaging biopsy was performed, the clinical parameters, the PET-based staging parameters, and the primary therapy received. Results: Thirty-four (34%) of the elderly patients included in the study had no preimaging biopsy. Compared with B(+) patients, B(-) patients were older (median age, 87 vs. 82 y; P < 0.01), with worse performance status (P < 0.01) and higher prostate-specific antigen (PSA) levels (median, 57 vs. 15.4 ng/mL; P < 0.01). On 68Ga-PSMA-11 PET/CT, all B(-) patients had avid disease, with trends toward higher rates of bone metastases (47.1% vs. 28.8%) and overall advanced disease (50% vs. 33.3%) than in B(+) patients. Among patients with localized (n = 36) or locally advanced (n = 25) disease, B(-) patients were less commonly referred than B(+) patients for definitive therapies (P < 0.01). However, higher age, Eastern Cooperative Oncology Group performance status, and PSA were other probable factors determining their therapeutic approach. Among 39 patients with advanced disease, 38 received hormonal therapy irrespective of their biopsy status. Among B(-) patients with advanced disease who were referred for hormonal therapy, 12 of 13 with follow-up data showed a biochemical or imaging-based response. Conclusion: Real-life experience with 68Ga-PSMA-11 PET/CT indicates that around one third of elderly patients are referred for imaging without a preimaging confirming biopsy. These patients are likely to be older, with a worse clinical status and higher PSA levels. Advanced disease might be more likely to be identified on their 68Ga-PSMA-11 PET/CT images, and if it is, their biopsy status does not preclude them from receiving hormonal therapy.

Diagnostic efficacy of positron emission computerized tomography scans in suspicious laryngeal findings postorgan preservation treatment.

BACKGROUND: Larynx preservation protocols (LPP) for glottic primary squamous cell carcinoma has gained popularity worldwide. Direct laryngoscopy (DL) with biopsy is mandated when recurrence is suspected. The efficacy of 18Fluoro-deoxy-glucose positron emission computerized tomography (PET-CT) as alternative first-line diagnostic investigation in suspected recurrence was evaluated. METHODS: A retrospective study of patients with suspicious fiber-optic findings at more than 12 weeks after LPP. Sensitivity, specificity, and the negative predictive value (NPV) of DL and PET-CT were compared. RESULTS: Seventy-two patients presenting 105 cases of suspicious events were included in this study. Fifty-two events were initially investigated by DL and 53 events by PET-CT. The sensitivity of DL and PET-CT was 56.25% and 100%, respectively. The NPV was 84% for DL and 100% for PET-CT (p = 0.015). CONCLUSION: Negative PET scans after LPP are highly accurate in ruling out recurrent/persistent disease and may spare the patient from negative biopsies.