CT Examination Reveals Extremely Small Stone in the Kidney with SAFIRE*

SOMATOM Definition AS64

Hatem Alkadhi, MD, MPH, University Hospital Zurich, Switzerland;
Andreas Blaha, Siemens Healthcare, Forchheim, Germany

 |  2011-06-14


A 39-year-old, male patient showed up in the emergency room with severe, persisting abdominal pain while continuously seeking a more comfortable position to lay down. Immediate observations indicated most likely an acute renal colic. The patient did not report a family history of kidney stones. He was immediately hydrated intravenously and transferred to the radiology department.


Standard imaging methods for this group of patients is a conventional abdominal X-ray image, followed by a non-contrast CT examination. Utilizing SAFIRE** (Sinogram Affirmed Iterative Reconstruction) together with an especially adapted, low dose acquisition protocol developed by Siemens, 1.6 mSv was sufficient to get good image quality and diagnostic accuracy. No kidney cysts, no pyelectasis could be detected, but using the series reconstructed with SAFIRE, a small stone could be seen in the right kidney.


Safire allowed to reliably identify a small stone in the right kidney. The diameter of the calculi was measured to be 0.3 x 0.2 mm. Due to its small size the likelihood that the stone will pass without further treatment is very high. Although the dataset is acquired with a very low radiation dose of 1.6 mSv, it does not appear noisy.


Examination Protocol

Scanner SOMATOM Definition AS64
Scan area Abdomen
Scan length 435 mm
Scan direction Cranio-Caudal
Scan time 18 s
Tube voltage 120 KV
Tube current 30 eff. mAs
Dose modulation CARE Dose4D
CTDIvol 2.41 mGy
DLP 108 mGy*cm
Eff.dose 1.6 mSv
Rotation time 0.5 s
Pitch 0.6
Slice collimation 64 x 0.6 mm
Slice width 2 mm
Spatial resolution 0.33 mm
Reconstruction increment 1.4 mm
Reconstruction kernel B30 / I30
Postprocesssing syngo.via Oncology

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