Precision and reliability of liver iodine quantification from spectral detector CT

TY - JOUR

T1 - Precision and reliability of liver iodine quantification from spectral detector CT

T2 - evidence from phantom and patient data

AU - Große Hokamp, Nils

AU - Abdullayev, Nuran

AU - Persigehl, Thorsten

AU - Schlaak, Max

AU - Wybranski, Christian

AU - Holz, Jasmin A

AU - Streichert, Thomas

AU - Alkadhi, Hatem

AU - Maintz, David

AU - Haneder, Stefan

PY - 2019/4

Y1 - 2019/4

N2 - OBJECTIVE: To comprehensively assess precision, reproducibility, and repeatability of iodine maps from spectral detector CT (SDCT) in a phantom and in patients with repetitive examination of the abdomen.METHODS: Seventy-seven patients who underwent examination two (n = 52) or three (n = 25) times according to clinical indications were included in this IRB-approved, retrospective study. The anthropomorphic liver phantom and all patients were scanned with a standardized protocol (SSDE in patients 15.8 mGy). In patients, i.v. contrast was administered and portal venous images were acquired using bolus-tracking technique. The phantom was scanned three times at three time points; in one acquisition, image reconstruction was repeated three times. Region of interest (ROI) were placed automatically (phantom) or manually (patients) in the liver parenchyma (mimic) and the portal vein; attenuation in conventional images (CI [HU]) and iodine map concentrations (IM [mg/ml]) were recorded. The coefficient of variation (CV [%]) was used to compare between repetitive acquisitions. If present, additional ROI were placed in cysts (n = 29) and hemangioma (n = 29).RESULTS: Differences throughout all phantom examinations were < 2%. In patients, differences between two examinations were higher (CV for CI/IM: portal vein, 2.5%/3.2%; liver parenchyma, -0.5%/-3.0% for CI/IM). In 80% of patients, these differences were within a ± 20% limit. Differences in benign liver lesions were even higher (68% and 38%, for CI and IM, respectively).CONCLUSIONS: Iodine maps from SDCT allow for reliable quantification of iodine content in phantoms; while in patients, rather large differences between repetitive examinations are likely due to differences in biological distribution. This underlines the need for careful clinical interpretation and further protocol optimization.KEY POINTS: • Spectral detector computed tomography allows for reliable quantification of iodine in phantoms. • In patients, the offset between repetitive examinations varies by 20%, likely due to differences in biological distribution. • Clinically, iodine maps should be interpreted with caution and should take the intra-individual variability of iodine distribution over time into account.

AB - OBJECTIVE: To comprehensively assess precision, reproducibility, and repeatability of iodine maps from spectral detector CT (SDCT) in a phantom and in patients with repetitive examination of the abdomen.METHODS: Seventy-seven patients who underwent examination two (n = 52) or three (n = 25) times according to clinical indications were included in this IRB-approved, retrospective study. The anthropomorphic liver phantom and all patients were scanned with a standardized protocol (SSDE in patients 15.8 mGy). In patients, i.v. contrast was administered and portal venous images were acquired using bolus-tracking technique. The phantom was scanned three times at three time points; in one acquisition, image reconstruction was repeated three times. Region of interest (ROI) were placed automatically (phantom) or manually (patients) in the liver parenchyma (mimic) and the portal vein; attenuation in conventional images (CI [HU]) and iodine map concentrations (IM [mg/ml]) were recorded. The coefficient of variation (CV [%]) was used to compare between repetitive acquisitions. If present, additional ROI were placed in cysts (n = 29) and hemangioma (n = 29).RESULTS: Differences throughout all phantom examinations were < 2%. In patients, differences between two examinations were higher (CV for CI/IM: portal vein, 2.5%/3.2%; liver parenchyma, -0.5%/-3.0% for CI/IM). In 80% of patients, these differences were within a ± 20% limit. Differences in benign liver lesions were even higher (68% and 38%, for CI and IM, respectively).CONCLUSIONS: Iodine maps from SDCT allow for reliable quantification of iodine content in phantoms; while in patients, rather large differences between repetitive examinations are likely due to differences in biological distribution. This underlines the need for careful clinical interpretation and further protocol optimization.KEY POINTS: • Spectral detector computed tomography allows for reliable quantification of iodine in phantoms. • In patients, the offset between repetitive examinations varies by 20%, likely due to differences in biological distribution. • Clinically, iodine maps should be interpreted with caution and should take the intra-individual variability of iodine distribution over time into account.

KW - Journal Article

U2 - 10.1007/s00330-018-5744-0

DO - 10.1007/s00330-018-5744-0

M3 - SCORING: Journal article

C2 - 30324387

VL - 29

SP - 2098

EP - 2106

JO - EUR RADIOL

JF - EUR RADIOL

SN - 0938-7994

IS - 4

ER -