Performance of low-dose, digital X-ray scanning (LODOX) compared to conventional radiography (CR) in the diagnostics of ureteral stones

Transcription

1 Performance of low-dose, digital X-ray scanning (LODOX) compared to conventional radiography (CR) in the diagnostics of ureteral stones Poster No.: C-0193 Congress: ECR 2015 Type: Authors: Keywords: DOI: Scientific Exhibit A. Christe, S. Hnilicka, V. Obmann, B. Roth; Bern/CH Abdomen, Kidney, Emergency, Conventional radiography, Experimental, Radiation safety, Calcifications / Calculi, Dosimetric comparison /ecr2015/C-0193 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 11

2 Aims and objectives LODOX Statscan is a whole-body, low-dose X-ray scanner with digital enhancement and enlargement capabilities which was originally developed in the 1980#s in order to prevent smuggling of diamonds by mineworkers in South Africa. Ten years ago it was introduced as a screening device for the examination of trauma patients requiring only about one third of the radiation used for CR [1, 2]. The use in polytrauma screening in cases of falls or violent trauma (motor vehicle accidents) has been documented by several groups [3-8]. However, innovative clinicians have uncovered more varied uses for the technology that have proven useful in nontraumatic emergency medicine; for instance, the visualization of ventriculoperitoneal shunts or foreign bodies (gun-shot wounds, body packers) an even emergency room arteriography was performed [9]. The Lodox Statscan images have been proved to have equal or better image quality as conventional X-ray, despite the speed and low radiation of imaging [4, 5, 7, 10], finding a sensitivity of 62% and specificity of 99% for various diseases [7]. With decreasing voltage of the x-ray-tube the contrast between bones and soft tissue or between contrast and arterial clots increase [11]. A phenomenon well known and used in dual-energy CT for CT-spectroscopy. A phantom study could show a superiority for the detection of urinary stones compared to CR [12]. We thus prospectively evaluated LODOX as primary diagnostic imaging for ureteral stones. Methods and materials 28 emergency patients (median age: 50 years; range: 25-77; median BMI 27.6; range: ) presenting with acute renal colic due to a unilateral ureteral stone were included. All 28 patients underwent LODOX, CR and CT imaging: During LODOX scanning (Lodox Systems (Pty) Ltd, South Africa), the C-arm moves from the head to the foot of the patient at up to 138 mm/s, emitting a thin, pencil beam of X-rays which are detected by the narrow detector. This configuration (known as LSSR) eliminates most of the scatter associated with conventional fan-beam radiography and accounts for the very low radiation dose required for the machine to form X-ray images [1]. CR plain abdominal radiography was conducted in a prone position (flat panel detector: Fuji XU-D1, Fujifilm Medical; source: Siemens, Forchheim, Germany) and CT imaging was performed with a 128-row multi- detector CT unit (Somatom Definition Flash, Siemens, Forchheim, Germany). Spiral CT scan was acquired at 120 kvp, 100 mas and a reconstruction slice thickness of 1 mm. Page 2 of 11

3 The CR and LODOX images were read by 2 blinded readers (one expert with 12 years' experience in stone detection and surveillance on plain film and one first year resident) who were only aware of the side of the colic. Stone location (if detectable) was marked on a diagram. All stone locations within a variation of 3 cm were classified as correct. The readings were compared to the CT-images, which is the gold standard (Fig. 1 and 2). CT imaging reaches a sensitivity and specificity of % [13, 14] and delivers even information on the composition of the renal calculi [15]. Statistical comparisons of stone detection rate were performed with the McNemar test and Body mass index comparison was calculated using the Mann-Whitney test. MedCalc Version (Belgium) was used and the level of significance was set to p<0.05. Images for this section: Page 3 of 11

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5 Fig. 1: Gold standard CT imaging reveals nephrolithiasis on this coronal reconstruction Page 5 of 11

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7 Fig. 2: Ureterolithiasis on coronal reconstructions Page 7 of 11

8 Results Median stone size was 5 mm (range: 2-12), median stone density was 800 Hounsfield units (HU; range: ). The detection rates of LODOX vs. CR for the expert and the resident were 89% (25/28) vs. 68% (19/28; p = 0.02), and 71% (21/28) vs. 61% (17/28; p = 0.15), respectively. Taken the results of the expert and the resident together (n = 56 stone detections), 68% (15/22) and 77% (17/22) of proximal, 100% (8/8) and 38% (3/8) of mid, and 85% (22/26) and 62% (16/26) of distal ureteral stones were detected with LODOX and CR, respectively (Fig. 3). The three stones that were not detected with LODOX (and also not with CR) by the expert had low density (# 300 HU). Additionally, two of these stones had low size (< 3mm), and the third was a 100% uric acid stone in the mid-ureter. The 3 patients who had ureteral stones that could not be detected by the expert with LODOX were all obese (BMI # 33). The finding that LODOX detection of ureteral stones was more challenging in obese patients was confirmed by the junior resident's results; the BMI of patients with detected vs. undetected stones was 27.2 and 32.4, respectively (p = 0.044). Images for this section: Page 8 of 11

9 Fig. 3: Nephrolithiasis and Ureterolithias are better detectable on the LODOX images Page 9 of 11

10 Conclusion The detection rate for ureteral stones using LODOX was as high as 89% in experienced hands. LODOX was significantly better for primary stone detection than CR. Due to its low radiation and its high sensitivity LODOX seems to be a promising imaging tool for patients presenting with acute renal colic. However, it has its weakness e.g. in obese patients. Personal information References 1. Beningfield SJ, Potgieter JH, Bautz P, et al. Evaluation of a new type of direct digital radiography machine. South African Medical Journal. 1999;89(11 I): UNSCEAR. UNSCEAR, 2000 Report to General Assembly. New York, NY, USA: UNSCEAR; United Nations scientific committee on the effects of atomic radiation. 3. Evangelopoulos DS, Deyle S, Zimmermann H, Exadaktylos AK. Personal experience with whole-body, low-dosage, digital X-ray scanning (LODOX-Statscan) in trauma. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. 2009;17:41 4. Beningfield S, Potgieter H, Nicol A, et al. Report on a new type of trauma full-body digital X-ray machine. Emergency Radiology. 2003;10(1): Boffard KD, Goosen J, Plani F, Degiannis E, Potgieter H. The use of low dosage X-ray (lodox/statscan) in major trauma: comparison between low dose X-ray and conventional X-ray techniques. Journal of Trauma-Injury, Infection and Critical Care. 2006;60(6): Mulligan ME, Flye CW. Initial experience with Lodox Statscan imaging system for detecting injuries of the pelvis and appendicular skeleton. Emergency Radiology. 2006;13(3): Deyle S, Wagner A, Benneker LM, et al. Could full-body digital X-ray (LODOX- Statscan) screening in trauma challenge conventional radiography? The Journal of Trauma. 2009;66(2): Page 10 of 11

11 8. Exadaktylos AK, Benneker LM, Jeger V, et al. Total-body digital X-ray in trauma. An experience report on the first operational full body scanner in Europe and its possible role in ATLS. Injury. 2008;39(5): Whiley SP, Mantokoudis G, Ott D, Zimmerman H, Exadaktylos AK. A Review of Full-Body Radiography in Nontraumatic Emergency Medicine. Emergency Medicine International 2012; 2012: Mervis SE, Matsumoto J, Shanmuganathan K, Shah P, Miller L. Use of a total body digital radiography (Statscan) for acute trauma imaging: preliminary experience in comparison with traditional computed Radiography. Proceedings of the American Society of Emergency Radiology Scientific Conference; 2005; Chicago, Ill, USA 11. Szucs-Farkas Z, Schaller C, Bensler S, Patak MA, Vock P, Schindera ST. Detection of pulmonary emboli with CT angiography at reduced radiation exposure and contrast material volume: comparison of 80 kvp and 120 kvp protocols in a matched cohort. Investigative Radiology 2009;44(12): Szucs-Farkas Z, Chakraborty DP, Thoeny HC, Loupatatzis C, Vock P, Bonel H. Detection of urinary stones at reduced radiation exposure: a phantom study comparing computed radiography and a low-dose digital radiography linear slit scanning system. American Journal of Roentgenology 2009; 192(6):W271-W Hamm M, Wawroschek F, Weckermann D, et al. Unenhanced helical computed tomography in the evaluation of acute flank pain. European Urology 2001; 39: Boulay I, Holtz P, Foley WD, White B, Begun FP. Ureteral calculi: Diagnostic efficacy of helical CT and implications for treatment of patients. American Journal of Roentgenology 1999; 172: Saw KC, McAlteer JA, Monga AG, et al. Helical CT of urinary calculi: effect of composition, stone size, and scan collimation: American Journal of Roentgenology 2000; 175: Page 11 of 11