Ashkan A. Malayeri

Abdominal Imaging with Contrast-enhanced Photon-counting CT: First Human Experience

PURPOSEnTo evaluate the performance of a prototype photon-counting detector (PCD) computed tomography (CT) system for abdominal CT in humans and to compare the results with a conventional energy-integrating detector (EID).nnnMATERIALS AND METHODSnThe study was HIPAA-compliant and institutional review board-approved with informed consent. Fifteen asymptomatic volunteers (seven men; mean age, 58.2 years ± 9.8 [standard deviation]) were prospectively enrolled between September 2 and November 13, 2015. Radiation dose-matched delayed contrast agent-enhanced spiral and axial abdominal EID and PCD scans were acquired. Spiral images were scored for image quality (Wilcoxon signed-rank test) in five regions of interest by three radiologists blinded to the detector system, and the axial scans were used to assess Hounsfield unit accuracy in seven regions of interest (paired t test). Intraclass correlation coefficient (ICC) was used to assess reproducibility. PCD images were also used to calculate iodine concentration maps. Spatial resolution, noise-power spectrum, and Hounsfield unit accuracy of the systems were estimated by using a CT phantom.nnnRESULTSnIn both systems, scores were similar for image quality (median score, 4; P = .19), noise (median score, 3; P = .30), and artifact (median score, 1; P = .17), with good interrater agreement (image quality, noise, and artifact ICC: 0.84, 0.88, and 0.74, respectively). Hounsfield unit values, spatial resolution, and noise-power spectrum were also similar with the exception of mean Hounsfield unit value in the spinal canal, which was lower in the PCD than the EID images because of beam hardening (20 HU vs 36.5 HU; P < .001). Contrast-to-noise ratio of enhanced kidney tissue was improved with PCD iodine mapping compared with EID (5.2 ± 1.3 vs 4.0 ± 1.3; P < .001).nnnCONCLUSIONnThe performance of PCD showed no statistically significant difference compared with EID when the abdomen was evaluated in a conventional scan mode. PCD provides spectral information, which may be used for material decomposition.

Catheter-directed gastric artery chemical embolization suppresses systemic ghrelin levels in porcine model

PURPOSEnTo prospectively test, in a porcine model, the hypothesis that catheter-directed gastric artery chemical embolization (GACE) can result in suppression of systemic ghrelin levels and affect weight gain.nnnMATERIALS AND METHODSnThis study, which had Animal Care and Use Committee approval, was performed in healthy, growing swine (weight range, 40-45 kg; n = 10). GACE was performed in five swine with the infusion of sodium morrhuate (125 mug) selectively into the gastric arteries that supply the fundus. Five control animals underwent a sham procedure with 5 mL of saline. Weight and fasting plasma ghrelin levels were obtained in animals at baseline and in weeks 1-4. Statistical testing for substantial differences in ghrelin blood levels over time and between treated and untreated animals was performed by using a cross-sectional time-series linear model with feasibility generalized least squares.nnnRESULTSnThe pattern of the change in ghrelin levels over time was significantly different between control and treated animals (P < .004). In treated animals, ghrelin levels were significantly reduced at week 1 (mean, 664.1 pg/mL +/- 103.1 [standard error of the mean], P < .02), week 2 (mean, 618.1 pg/mL +/- 180.4, P < .001), week 3 (mean, 578.4 pg/mL +/- 214.9, P < .001), and week 4 (mean, 876.6 pg/mL +/- 228.6, P < .03) relative to baseline (mean, 1006.3 pg/mL +/- 190.1). The percentage change in serum ghrelin values in swine treated with GACE decreased from baseline to -34%, -38.6%, -42.5%, and -12.9% during weeks 1-4, respectively. In control swine, percentage change in serum ghrelin was -1.7%, -9.7%, +2.6%, and +18.2% during weeks 1-4, respectively. At the end of 4 weeks, control swine continued to gain weight, with a 15.1% increase from their original weight, while the weight in swine treated with GACE plateaued at an increase of 7.8% from the original weight.nnnCONCLUSIONnCatheter-directed GACE can suppress the appetite hormone ghrelin and affect weight gain.

The clinical spectrum of Erdheim-Chester disease: an observational cohort study

Erdheim-Chester Disease (ECD) is a rare, potentially fatal, multi-organ myeloid neoplasm occurring mainly in adults. The diagnosis is established by clinical, radiologic, and histologic findings; ECD tumors contain foamy macrophages that are CD68+, CD163+, CD1a-, and frequently S100-. The purpose of this report is to describe the clinical and molecular variability of ECD. Sixty consecutive ECD patients (45 males, 15 females) were prospectively evaluated at the NIH Clinical Center between 2011 and 2015. Comprehensive imaging and laboratory studies were performed, and tissues were examined for BRAF V600E and MAPK pathway mutations. Mean age at first manifestations of ECD was 46 years; a diagnosis was established, on average, 4.2 years after initial presentation. Bone was the most common tissue affected, with osteosclerosis in 95% of patients. Other manifestations observed in one-third to two-thirds of patients include cardiac mass and periaortic involvement, diabetes insipidus, retro-orbital infiltration, retroperitoneal, lung, CNS, skin and xanthelasma, usually in combination. Methods of detection included imaging studies of various modalities. Mutation in BRAF V600E was detected in 51% of 57 biopsies. One patient had an ARAF D228V mutation, and one had an activating ALK fusion. Treatments included interferon alpha, imatinib, anakinra, cladribine, vemurafenib and dabrafenib with trametinib; eleven patients received no therapy. The diagnosis of ECD is elusive because of the rarity and varied presentations of the disorder. Identification of BRAF and other MAPK pathway mutations in biopsies improves ECD diagnosis, allows for development of targeted treatments, and demonstrates that ECD is a neoplastic disorder.

18F-Fluorodeoxyglucose–Positron Emission Tomography As an Imaging Biomarker in a Prospective, Longitudinal Cohort of Patients With Large Vessel Vasculitis

To assess the clinical value of 18F‐fluorodeoxyglucose (FDG) positron emission tomography (PET) in a prospective cohort of patients with large vessel vasculitis (LVV) and comparator subjects.

Evaluation of optimized breath-hold and free-breathing 3D ultrashort echo time contrast agent-free MRI of the human lung

To evaluate an optimized stack of radials ultrashort echo time (UTE) 3D magnetic resonance imaging (MRI) sequence for breath‐hold and free‐breathing imaging of the human lung.

Advances in medical imaging for the diagnosis and management of common genitourinary cancers

Medical imaging of the 3 most common genitourinary (GU) cancers-prostate adenocarcinoma, renal cell carcinoma, and urothelial carcinoma of the bladder-has evolved significantly during the last decades. The most commonly used imaging modalities for the diagnosis, staging, and follow-up of GU cancers are computed tomography, magnetic resonance imaging (MRI), and positron emission tomography (PET). Multiplanar multidetector computed tomography and multiparametric MRI with diffusion-weighted imaging are the main imaging modalities for renal cell carcinoma and urothelial carcinoma, and although multiparametric MRI is rapidly becoming the main imaging tool in the evaluation of prostate adenocarcinoma, biopsy is still required for diagnosis. Functional and molecular imaging using 18-fluorodeoxyglucose-PET and sodium fluoride-PET are essential for the diagnosis, and especially follow-up, of metastatic GU tumors. This review provides an overview of the latest advances in the imaging of these 3 major GU cancers.

Feasibility of Dose-reduced Chest CT with Photon-counting Detectors: Initial Results in Humans

Purpose To investigate whether photon-counting detector (PCD) technology can improve dose-reduced chest computed tomography (CT) image quality compared with that attained with conventional energy-integrating detector (EID) technology in vivo. Materials and Methods This was a HIPAA-compliant institutional review board-approved study, with informed consent from patients. Dose-reduced spiral unenhanced lung EID and PCD CT examinations were performed in 30 asymptomatic volunteers in accordance with manufacturer-recommended guidelines for CT lung cancer screening (120-kVp tube voltage, 20-mAs reference tube current-time product for both detectors). Quantitative analysis of images included measurement of mean attenuation, noise power spectrum (NPS), and lung nodule contrast-to-noise ratio (CNR). Images were qualitatively analyzed by three radiologists blinded to detector type. Reproducibility was assessed with the intraclass correlation coefficient (ICC). McNemar, paired t, and Wilcoxon signed-rank tests were used to compare image quality. Results Thirty study subjects were evaluated (mean age, 55.0 years ± 8.7 [standard deviation]; 14 men). Of these patients, 10 had a normal body mass index (BMI) (BMI range, 18.5-24.9 kg/m2; group 1), 10 were overweight (BMI range, 25.0-29.9 kg/m2; group 2), and 10 were obese (BMI ≥30.0 kg/m2, group 3). PCD diagnostic quality was higher than EID diagnostic quality (P = .016, P = .016, and P = .013 for readers 1, 2, and 3, respectively), with significantly better NPS and image quality scores for lung, soft tissue, and bone and with fewer beam-hardening artifacts (all P < .001). Image noise was significantly lower for PCD images in all BMI groups (P < .001 for groups 1 and 3, P < .01 for group 2), with higher CNR for lung nodule detection (12.1 ± 1.7 vs 10.0 ± 1.8, P < .001). Inter- and intrareader reproducibility were good (all ICC > 0.800). Conclusion Initial human experience with dose-reduced PCD chest CT demonstrated lower image noise compared with conventional EID CT, with better diagnostic quality and lung nodule CNR.

Imaging muscle-invasive and metastatic urothelial carcinoma

Purpose of review Muscle-invasive bladder cancer (MIBC) comprises approximately one-third of bladder cancers and is associated with significant morbidity and mortality. Accurate staging of bladder cancer is essential because of significantly different treatment options and the consequences of inaccurate staging. The current recommended method for staging is transurethral resection of the bladder tumor followed by contrast-enhanced computed tomography (CT). In this review, we discuss cross-sectional imaging approaches used to assess local, nodal, and distant metastases in MIBC. Recent findings Determining the most accurate imaging method for staging MIBC is a contentious issue. CT with contrast is a practical approach; however, there is potential for understaging of small lymph nodes or foci of metastasis. Multiparametric MRI is emerging as the imaging modality of choice in tumor staging, with a reported accuracy of more than 90%. Locoregional lymph node metastasis can also be accurately evaluated using functional MRI and specific contrast agents with paramagnetic characteristics. PET/CT with conventional radiotracers is a common imaging modality for staging distant metastases. Summary Conventional imaging methods for evaluating MIBC are of limited use. However, recent advances in molecular imaging, targeted contrast agents, and functional MRI have shown promising results for the staging of bladder cancer.

Prevalence of Cancer at Baseline Screening in the National Cancer Institute Li-Fraumeni Syndrome Cohort

Importance Establishment of an optimal cancer surveillance program is important to reduce cancer-related morbidity and mortality in individuals with Li-Fraumeni syndrome, a rare, highly penetrant cancer predisposition syndrome. Objective To determine the feasibility and efficacy of a comprehensive cancer screening regimen in Li-Fraumeni syndrome, using multiple radiologic techniques, including rapid whole-body magnetic resonance imaging (MRI) and laboratory measurements. Design, Setting, and Participants Baseline evaluation of a prospective cancer screening study was conducted from June 1, 2012, to July 30, 2016, at the National Cancer Institute, National Institutes of Health (an academic research facility). Participants included 116 individuals with Li-Fraumeni syndrome with a germline TP53 pathogenic variant who were aged 3 years or older at the time of baseline screening and had not received active cancer therapy at least 6 months prior to screening. Main Outcomes and Measures Detection of prevalent cancer with multimodal screening techniques and the need for additional evaluation. Results Of the 116 study participants, 77 (66.4%) were female; median age was 37.6 years (range, 3-68 years). Baseline cancer screening led to the diagnosis of cancer in 8 (6.9%) individuals (2 lung adenocarcinomas, 1 osteosarcoma, 1 sarcoma, 1 astrocytoma, 1 low-grade glioma, and 2 preinvasive breast cancers [ductal carcinoma in situ]); all but 1 required only resection for definitive treatment. A total of 40 (34.5%) participants required additional studies to further investigate abnormalities identified on screening, with 32 having incidental, benign, or normal findings, resulting in a false-positive rate of 29.6%. Non-MRI techniques, including baseline blood tests, abdominal ultrasonography in children, mammography, and colonoscopy, did not lead to a diagnosis of prevalent cancer in our cohort. Conclusions and Relevance This study describes the establishment and feasibility of an intensive cancer surveillance protocol for individuals with Li-Fraumeni syndrome. Prevalent cancers were detected at an early stage with baseline whole-body, brain, and breast MRI. Prospective screening of the participants is under way.

Three-dimensional T1 and T2* mapping of human lung parenchyma using interleaved saturation recovery with dual echo ultrashort echo time imaging (ITSR-DUTE).

To develop and assess a new technique for three‐dimensional (3D) full lung T1 and T2* mapping using a single free breathing scan during a clinically feasible time.