title: Abdominal Imaging with Contrast-enhanced Photon-counting CT: First Human Experience.
abstract: OBJECTIVE
  To 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).
  
  
  METHODS
  The 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.
  
  
  RESULTS
  In 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).
  
  
  CONCLUSIONS
  The 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.
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: Amir
authors: A
authors: Pourmorteza
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: Rolf
authors: R
authors: Symons
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: Veit
authors: V
authors: Sandfort
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: Marissa
authors: M
authors: Mallek
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: Matthew K
authors: MK
authors: Fuld
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: Gregory
authors: G
authors: Henderson
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: Elizabeth C
authors: EC
authors: Jones
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: Ashkan A
authors: AA
authors: Malayeri
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: Les R
authors: LR
authors: Folio
authors: From Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10, Bethesda, MD 20892 (A.P., R.S., V.S., M.M., G.H., E.C.J., A.A.M., L.R.F., D.A.B.); and Siemens Medical Solutions, Malvern, Pa (M.K.F.).
authors: David A
authors: DA
authors: Bluemke
mesh_terms: D000368:Aged; D003287:Contrast Media; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017785:Photons; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D011860:Radiography, Abdominal / Q000295:instrumentation*; D012666:Semiconductors; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*
chemical_list: D003287:Contrast Media