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Acta Radiol. 2014 Nov;55(9):1137-44. doi: 10.1177/0284185113513761. Epub 2013 Nov 20.

Quarter regular dose non-enhanced CT for urinary stone: added value of adaptive statistical iterative reconstruction.

Author information

1
Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea radiresi@gmail.com.
2
Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea.

Abstract

BACKGROUND:

As urinary stone diseases are common in young adults and have a high recurrence rate, repetitive computed tomography (CT) scans would increase the radiation hazard. Therefore, CT radiation dose reduction is needed in the diagnosis of urinary stones.

PURPOSE:

To prospectively evaluate the added value of adaptive statistical iterative reconstruction (ASIR) applied to half-dose (HDCT) and quarter regular dose non-enhanced CT (QDCT) for the detection of urinary stones.

MATERIAL AND METHODS:

One hundred and twelve consecutive patients who presented with acute flank pain and had clinically suspected urinary stones were initially eligible. All patients underwent non-enhanced CT that consisted of HDCT (120 kVp, 100 mAs) and QDCT (120 kVp, 40 mAs). The images were reconstructed separately with a 50% ASIR blending ratio. Two radiologists independently performed a 2-week interval reading to detect urinary stones on a per stone basis (size ≥1 mm) from the QDCT images to the ASIR applied images. Two weeks later, the HDCT images were analyzed in the same manner. The CT image noise was measured for each image set. The sensitivity for urinary stone detection for each set was compared using the McNemar test.

RESULTS:

A total of 114 urinary stones were found in 48 patients (37 men, 11 women; mean age, 46 years; range, 19-71 years). After applying ASIR to the QDCT images, the sensitivity increased from 70% to 80% for reader 1 and from 69% to 82% for reader 2 (P = 0.001, respectively). However, in the HDCT images, the sensitivity was unchanged for both readers (reader 1, 87%; reader 2, 89%). The measured noise significantly decreased from 40.2 to 27.7 after applying ASIR to the QDCT images and from 25.1 to 17.6 after applying ASIR to the HDCT images (P = 0.001 for both).

CONCLUSION:

Although ASIR showed no added diagnostic value for HDCT images, it improved the sensitivity for the detection of urinary stones based on QDCT images.

KEYWORDS:

Iterative reconstruction; computed tomography; image reconstruction; radiation dosage; urinary stone

PMID:
24259297
DOI:
10.1177/0284185113513761
[Indexed for MEDLINE]
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