Abdominal Radiology

, Volume 44, Issue 10, pp 3350–3358 | Cite as

Reducing radiation dose for multi-phase contrast-enhanced dual energy renal CT: pilot study evaluating prior iterative reconstruction

  • Patrick J. Navin
  • Bohyun Kim
  • Michael L. Wells
  • Ashish Khandelwal
  • Ahmed F. Halaweish
  • Taylor R. Moen
  • Matthew P. Johnson
  • Shannon McCollough
  • Yong Suk Lee
  • Shuai Leng
  • Cynthia H. McCollough
  • Joel G. FletcherEmail author



Prior iterative reconstruction (PIR) uses spatial information from one phase of enhancement to reduce image noise in other phases. We sought to determine if PIR could reduce radiation dose while preserving observer performance and CT number at multi-phase dual energy (DE) renal CT.


CT projection data from multi-phase DE renal CT examinations were collected. Images corresponding to 40% radiation dose were reconstructed using validated noise insertion and PIR. Three genitourinary radiologists examined routine and 40% dose PIR images. Probability of malignancy was assessed [from 0 to 100] with malignancy assumed at probability ≥ 75. Observer performance was compared on a per patient and per lesion level. CT number accuracy was measured.


Twenty-three patients had 49 renal lesions (11 solid renal neoplasms). CT number was nearly identical between techniques (mean CT number difference: unenhanced 2 ± 2 HU; enhanced 4 ± 4 HU). AUC for malignancy was similar between multi-phase routine dose DE and lower dose PIR images [per patient: 0.950 vs. 0.916 (p = 0.356); per lesion: 0.931 vs. 0.884 (p = 0.304)]. Per patient sensitivity was also similar (78% routine dose vs. 82% lower dose [p ≥ 0.99]), as was specificity (91% routine dose vs. 93% lower dose PIR [p > 0.99]), with similar findings on a per lesion level. Subjective image quality was also similar (p = 0.34).


Prior iterative reconstruction is a new reconstruction method for multi-phase CT examinations that promises to facilitate radiation dose reduction by over 50% for multi-phase DE renal CT exams without compromising CT number or observer performance.


Iterative reconstruction Renal neoplasms Radiation dosage Computed tomography, x-ray 



Authors wish to express appreciation to Kris Nunez for her assistance in preparation of the manuscript.


This work was funded in part by a research grant to the author’s institution from Siemens Healthineers.

Compliance with ethical standards

Conflict of interest

Dr. Halaweish is an employee of Siemens Healthineers. Drs. McCollough and Fletcher receive grant support to their institution from Siemens Healthineers, which provided the offline computer workstation and prior iterative reconstruction software examined in this work.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of RadiologyMayo ClinicRochesterUSA
  2. 2.Siemens HealthineersMalvernUSA
  3. 3.Department of Health Sciences ResearchMayo ClinicRochesterUSA

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