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PEER REVIEW
CT Evaluation of Flank Pain And Suspected Urolithiasis AHMED K ALSHAMAKHI, BSc LUKE C BARCLAY, PhD GEORGIA HALKETT, PhD GIRISH KUKADE, MD DILIP MUNDHADA, MD RAVI R UPPOOR, DMRD PRADNYA GAWAI, MD Background Acute renal colic is the most common clinical indication among patients seen in emergency departments. Studies have
shown that 2% to 3% of people will experience an episode of acute renal colic during their lifetime. Objective The objective of this study was to create and pilot test a single efficient medical imaging examination that can assess the
entire urinary system and the surrounding organs’ parenchyma for flank pain, suspected urolithiasis or both. Methods Participants were scanned using a single-slice computed tomography unit (Philips Secura, Philips Healthcare, Boston, Massachusetts). A total of 57 patients who were suffering from flank pain, suspected of having urinary stones or both participated in the study. Results and Conclusion The results indicate that nonenhanced CT scans facilitate more accurate assessments in the diagnosis of acute flank pain and urolithiasis than other medical imaging evaluations such as KUB radiographs (kidneys, ureters and bladder ), intravenous urography and ultrasonography. In addition, the current study showed that patients did not experience any complications following the use of water as an oral contrast media.
A
pproximately 2% to 3% of people will experience an episode of acute renal colic during their lifetime. It is the most common clinical indication that is seen in accident and emergency (A/E) departments on a daily basis.1,2 In the A/E department at the Armed Forces Hospital (AFH) in the Sultanate of Oman, approximately 50 patients present per month with this condition. This condition is not gender or age specific. Numerous investigators have studied the impact of computed tomography (CT) scans in medicine and particularly in uroradiology.1-14 Nonenhanced computed tomography (NECT) has been widely accepted as the standard technique for evaluating flank pain and suspected urolithiasis since it first was reported in 1994.8,15 Currently, in the AFH, patients with flank pain and patients with suspected urolithiasis are investigated using the following imaging series: conventional kidneys, ureter and bladder (KUB) radiographs, intravenous urography
(IVU), ultrasonography and, in some cases, CT scans for further evaluation. The main objective of this study was to create a single, efficient medical imaging exam that can completely assess the entire urinary system and the surrounding organs’ parenchyma. Ultimately, the use of this technique will improve the medical management of patients and reduce departmental costs. The second objective of this study was to test the use of water as a natural oral contrast media to diagnose flank pain or suspected urolithiasis. To readily differentiate the gastrointestinal (GI) tract from adjacent structures, an oral contrast agent is required for CT examination of the abdomen and pelvis.16 In this study, water was chosen because it can be resorbed by the body, differentiate the GI tract clearly and provides an outline of the stomach, intestines and urinary bladder. Also, water is relatively cheap, safe and better tolerated by patients than other contrast agents (eg, water-soluble media such as diatrizoate meglumine
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and diatrizoate sodium and contrast agents containing barium sulphate).
Literature Review Patients with flank pain and suspected urolithiasis routinely are examined with conventional KUB radiography before they are examined by any advanced medical imaging tests. KUB radiography is an effective baseline examination because it is less costly than other imaging exams and enables radiologists to detect calcifications, locate any stones and assess bowel gas and fecal debris.8 For decades, IVU and ultrasound have been the traditional methods for evaluating patients with acute urinary tract colic.14 IVU allows estimation of renal function and the degree of ureteral obstruction, localization of a calculus and detection of anatomical abnormalities in the urinary system. 8 However, the use of IVU in the diagnostic approach of acute flank pain has been challenged by several limitations. Heidenreich et al, 8 Memarsadeghi et al,17 Raby18 and many others have reported that the IVU examination suffers from inherent limitations, such as a considerably lower sensitivity than CT for small stones and ureteral stones (52%), difficult visualization of radiolucent stones and differentiation of them from other filling defects such as tumor, and IV contrast media-induced nephrotoxicity. Also, the presence of bowel gas and fecal materials obscure the target anatomy. Previous studies8,19,20 claimed that ultrasound had a sensitivity of 96.3% for diagnosing ureteral obstruction. However, it was found to be less sensitive than CT in direct visualization of ureteral stones, recording a sensitivity of 19%. More importantly, in the absence of renal calculi or hydronephrosis, sonography has a limited role in diagnosing alternate pathology. Because of its poor sensitivity, dependence on the sonographer’s skill and experience, and the limited ability to adjust the quality of images, ultrasound should be reserved for pediatric and pregnant patients.19,20 CT scanning has undergone many changes and developments since its introduction in the early 1970s by Godfrey N Hounsfield, and CT technology and techniques continue to evolve. One example is CT urography,21 which developed out of the desire to create a single efficient medical imaging test that can completely assess the entire urinary system and the surrounding organs’ parenchyma.5 Since it was first reported by Smith et al in 1994 at the annual meeting of the Radiological Society of North America, NECT has become a standard and widely accepted technique for evaluating flank pain and
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suspected urolithiasis.15 NECT enables the radiologist to conduct anatomical assessment, evaluate urolithiasis, detect acute hematoma, obtain baseline density measurement of renal masses and assess surrounding body parenchyma. Also, almost all urinary tract calculi appear radiopaque on NECT.15 It has been reported in both comparative and observational studies that NECT has a sensitivity of 94% to 100% and a specificity of 92% to 100% in evaluating urinary and nonurinary tract related pathologies.2,9 Also, Chowdhury et al stated that CT can depict other pathologies that may cause acute flank pain, such as appendicitis, diverticulitis, ectopic pregnancy, biliary colic, salpingitis, ruptured abdominal aortic aneurysm and many others.3 Memarsadeghi et al,17 Kenney 22 and many others claimed that NECT has the following additional advantages compared with other diagnostic imaging modalities: inherent high soft-tissue contrast resolution, accurate stone measurement, fast data acquisition and the ability to diagnose alternative abdominal diseases that mimic the symptoms of renal colic. Furthermore, IV iodinated contrast media are not required for NECT scanning. The current study aimed to create and pilot test a single efficient medical imaging test that can assess the entire urinary system and the surrounding organs’ parenchyma using an efficient and effective scanning protocol to evaluate patients with flank pain, suspected urolithiasis or both. Unlike previous studies, we investigated the value of extending the scan area from the dome of the diaphragm to the symphysis pubis. Also, the current study evaluated the advantages of the designed scanning protocol (5 mm slice thickness and table increment, 3 mm reconstruction index and a pitch of 1) in visualizing small pathologies (eg, tiny calculi).
Methods Participants This study was conducted in the Armed Forces Hospital in Oman from December 2007 to February 2008, after ethical approval was granted from relevant ethics committees. The study examined only patients presenting with a first episode of clinically suspected urolithiasis. The study participants were mentally competent adults who had normal renal function tests. The study excluded patients younger than 18 years, patients older than 65 years, pregnant women, patients with reduced mental capacity and patients with abnormal renal function tests.
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Apparatus and Scanning Protocol All participants were scanned using a single slice CT Philips Secura scanner. The scans extended from the dome of the diaphragm to the symphysis pubis with 5 mm slice thickness and table increment, 3 mm reconstruction index and pitch of 1. A standardized viewing window (see Figure 1) was set at a window width of 350 and a window level of 50 to ensure the radiologists were reviewing the images using the same setting and viewing parameters. The scanning protocol used for the current study differed from previous studies in the following ways: Thinner slice sections were used than the 7 to 10 mm slice thicknesses previously reported and the scans extended from the dome of the diaphragm to the symphysis pubis, rather than from the kidneys to the symphysis pubis. This enabled more abdominal parenchyma to be covered and clearly visualized. These modifications were found to be advantageous for assessing flank pain and suspected urolithiasis. Oral Administration of Contrast Agent To opacify the entire GI tract, patients were asked to drink 900 ml of water approximately 40 minutes prior to the scan. Patients were instructed to drink an additional 100 ml of water immediately before the scan to distend the stomach. To ensure that the bladder was relatively full, patients were asked whether they felt as if they needed to urinate before the scan was performed. Documentation All scans were interpreted by the department radiologists and the results were recorded on evaluation sheets designed for the study. The evaluation sheet included the following information: urinary and nonurinary tract related findings; location, size and Hounsfield unit (HU) density of calculi (if present); and the presence of ancillary or secondary signs of calculi. These signs include the soft-tissue rim sign and perinephric fat stranding, as well as dilatation of the collecting system and ureter above a suspected stone and normal ureteral diameter below it. These signs are indicative of a localized inflammatory reaction or irritation caused by the presence or passing of a ureteral stone or other acute urinary obstruction. Both the soft-tissue rim sign and perinephric fat stranding are well visualized on CT because of the modality’s superiority ability to detect small tissue differences, which conventional radiography lacks.3 The evaluation sheet also indicated whether any further medical imaging tests were advised and the radiologists’ perspectives on the overall benefit of using NECT.
Figure 1. Standardized viewing window parameters used to
visualize stones (window width 350, window level 50).
Data Analysis All data were entered into SPSS Version 16 (SPSS Inc., Chicago, Illinois) and analyzed using descriptive statistics. Patients’ results were compared to determine the effectiveness of NECT and water enhancement in diagnosing flank pain and suspected urolithiasis.
Results Demographics Fifty-seven adult patients presenting consecutively with flank pain, suspected urolithiasis or both were examined with NECT in the AFH hospital. Nine patients were excluded from the study because of incomplete evaluation sheets and ineligibility due to their age (> 65 years). The evaluated group consisted of 30 men and 18 women, aged 19 to 58 years old (mean age 36.29, SD 9.67). Pathological Findings The NECT tests revealed 11 patients had negative findings and 37 patients had positive findings, including 26 findings related only to the urinary tract, 3 nonurinary tract related findings, and 8 patients with both urinary and nonurinary tract related findings (see Table 1). Stone Disease The NECT tests revealed stones of different sizes and HU densities in various parts of the urinary tract system. The smallest stone that was reported measured 1 mm and the largest was 13 mm. Many tiny stones
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Table 1 Urinary and Nonurinary Tract Related Findings Urinary tract related Urinary tract related calculi
(n)
Nonurinary Tract Related
(n)
34
Phleboliths
6 2
Renal scarring
2
Liver fatty infiltration
Renal parenchyma calcification
2
Calcified splenic artery
1
Hydronephrosis
1
Umbilical hernia
1
Urine extravasation
1
Hepatic lesion
Focal cortical thinning
1
detection. However, this technique only detected stones in 4 of the 6 cases. In the majority of cases, the CT scan protocol enabled calculi visualization without further postprocessing of images.
The Overall NECT Impression Ovarian pathology 1 The NECT scan outSpondylolysis 1 comes showed that the procedure was highly Bilateral paraspinal muscular informative and reliable Fatty infiltration and splenic cleft 1 in evaluating all participants’ findings. In 33 cases, NECT was informative and no further medical imaging evaluation was indicated. However, NECT scans were found to provide insufficient diagnostic information for 15 patients. These patients required additional tests to confirm their diagnosis (see Table 2). Although additional imaging was deemed necessary for 15 patients, these additional imaging tests were clinically insignificant and did not change the medical management for 5 (33%) of these patients. All 5 of these patients were found to have phleboliths, a common finding without any clinical significance and no required treatment. 1
Discussion The results of this study are consistent with previous research on the ability of Figure 2. Number of stones that were reported in each category of HU density. NECT in evaluating urinary and nonurinary tract related pathologies in patients with flank pain, suspected urolithiasis or were detected, but not measured and recorded because both.3,17,23 Furthermore, this study builds on previous of their immeasurable size. Figure 2 illustrates the studies in the following ways: First, the current study number of stones that were reported in each HU denscanning protocol enabled the visualization of stones sity category. smaller than 1 mm. Second, the scan extent used in this A total of 7 cases showed the rim sign, perinephric fat study covered more abdominal parenchyma than previstranding or both: 3 cases demonstrated both signs, 3 ous studies. These scans revealed pathologies that would cases demonstrated only the rim sign and 1 case showed have been missed if the scan were limited to CT KUB. minimal perinephric fat stranding. The Impact of the Study in Assessing Patients’ Pathologies The Use of Multiplanar Reformats Tamm et al2 and Gottlieb et al9 claimed that both comMultiplanar reformats from thinner postprocessed parative and observational studies have reported that CT axial slices were used in 6 cases for further calculi has become the reference standard in evaluating urinary
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support for Lee et al, who reported that the size of the stone and Further Imaging Test (n) Indication the patient’s symptoms significantly influence KUB 5 Phlebolith assessment outcome, patient manEnhanced CT/IVU 3 Upper calix dilatation or cyst agement or both.24 Most Location of renal upper pole calcification importantly, Sheafor et al claimed that on Urine extravasation many occasions imaging Enhanced CT 2 To confirm ureteric stone position tests help in treatment Hypodense hepatic lesion planning and enable clinicians to determine IVU 1 Dilated renal pelvis and ureter whether surgery is necUltrasound 4 UVJ stone essary.25 For example, Lower ureteric stone when a stone measures less than 2 mm, analgeUpper calix calculi sics and hydration are Ovarian pathology advised, whereas when a stone measures more KUB = Kidney, ureter, bladder; CT = computed tomography; IVU = intravenous urography; UVJ = ureterovesical junction than 5 mm, surgery might be required. In addition, the current study revealed that the and nonurinary tract related pathologies, with high senmajority of the detected stones (37 calculi) had an HU sitivity of 94% to 100% and specificity of 92% to 100%. density of ≤ 300. The HU density was 301 to 700 for 23 Analysis of the current study data revealed that NECT was calculi and >701 for 3 calculi. It is presumed that the perceived to be highly effective in determining urinary majority of these stones, if small in size, require only tract related findings (see Table 1 and Figure 3). conservative management with no invasive surgical interAlthough the participants in this study were referred vention because of their low HU densities. Providing this for assessment of urinary tract related problems, the data to referring physicians helps determine the most study also provided information about nonurinary appropriate management based on size, HU density and tract related pathologies that may cause or mimic acute stone location. flank pain. This result supports previous studies by Chowdhury et al,3 Memarsadeghi et al17 and Sebastian Ancillary Signs in NECT and Tait,23 who claimed that CT can depict other nonLee et al reported that although numerous indepenurinary tract related pathologies (see Table 1 and Figure dent investigators argued that IVU or other tests were 4). Based on the NECT results, radiologists in this study necessary to look for evidence of the degree of obstrucwere able to conclusively diagnose or rule out renal caltion, this argument has fallen out of favor.24 The detecculi and other causes of flank pain. tion of direct and indirect signs on NECT allows identifiThe Study’s Effect on Assessing Urinary Calculi cation not only of the calculus, but also secondary signs, Data revealed that NECT enabled depiction of uriwhich can help guide patient management and evaluate nary calculi of various sizes and HU densities. The prognosis. Many of the secondary or ancillary signs on smallest stone that was reported was 1 mm and the largCT are in fact a result of the physiology of obstruction.7 est was 13 mm. As mentioned above, there were many In the current study, our attention was focused primarily tiny stones detected but not measured and recorded on the ability of NECT to detect such signs, which canbecause of their very small size. NECT has high sensitivnot be appreciated using traditional imaging modalities. ity and specificity in stone depiction and size evaluation Seven cases were detected by the supervising radiolocompared with conventional KUB radiography, which gists as illustrating the presence of secondary or ancilsignificantly overestimates the size of stones.8 lary signs, including the rim sign and perinephric fat stranding (see Figure 5). The findings of the current study provide empirical
Table 2 Further Medical Imaging Evaluations and Their Indications
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for phlebolith assessment would most likely not affect the patient’s medical management because there is no need to treat phleboliths. It can be argued that with the presence of previous KUB radiographs, the need for further examinations would be eliminated. The current study finding is consistent with Heidenreich et al in that CT is limited in its ability to provide information for a reliable phlebolith assessment, in which D C case KUB radiography is the imaging technique of choice. 8 It appeared that the majority of these additional examinations were for contrast-enhanced CT, and a few for IVU. This could be justified because contrastenhanced CT scans have inherent high soft-tissue contrast resolution and higher detection values and allow visualization of alternate patholoFigure 3. A. Right renal calculi and bilateral renal hydronephrosis. B. Focal cortical thinning in upper gies. This is consispole of left kidney (arrow). C. Urine extravasation in retroperitoneium space (arrow), D: Bilateral medultent with studies by lary calcification. Kenney,7Memarsadeghi et al15 and many others. Four patients were referred for ultrasound to assess Radiologists’ Impressions of NECT and upper calix calculi, lower ureteric and ureterovesical Indications for Further Imaging junction (UVJ) stones and ovarian pathology. This The study data have shown that the test was highly provides empirical support for findings by Heidenreich informative and reliable in evaluating participants’ et al who claimed that ultrasound enables the identifindings. In 33 cases NECT scans were informative and fication of stones located in the renal pelvis, calices, no further medical imaging evaluation was indicated. pyeloureteral junction, and UVJ area.8 However, 14 cases were found to have some limitations and 1 was noninformative. The Effect of Study Design Some patients (31.25%) needed to undergo confirBased on the study results and previous studies, matory imaging studies such as enhanced CT, KUB, there is no doubt that NECT is the modality of choice IVU and ultrasound (see Table 2). Of these further for evaluating flank pain and suspected urolithiasis recommended imaging studies, the KUB examination A
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B
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A
B
D
G
E
C
F
Figure 4. A. Splenic artery calcification (arrow). B. Hypodense hepatic lesion
(arrow). C. Liver fatty infiltration. D. Umbilical hernia. E. Fallopian tube calcification (arrow). F. Spondylolysis of L5 (arrow) G. Gross bilateral paraspinal muscles fatty infiltration (short arrows) and splenic artery cleft (long arrow).
because of the more complete assessments and greater information that can be obtained. However, the current study data found that there was no significant effect in giving patients an oral contrast media to assess flank pain and suspected urolithiasis. In addition, it was found that although patients had relatively full urinary bladders when they were scanned, some patients still needed
to be referred for KUB radiography to differentiate between phleboliths and urinary bladder calculi. The nonsignificant effect of using oral contrast media may, however, be attributable to none of the scanned participants having inflammatory bowel conditions such as appendicitis or gastric pathologies such as lesions. Despite the insignificant findings regarding the impact of using
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The scanning protocol used in this study was found to be successful because none of the participants required thinner sections to be imaged after their initial scans were performed. Rather, this study protocol enabled the depiction of 1 mm stones as well as other immeasurable tiny calculi. Furthermore, the scan extent used in this study (from the dome of diaphragm to the symphysis pubis) also was found to be advantageous. This scanning extent subsequently revealed pathologies such as fatty infiltration of the liver and hypodense hepatic lesions (see Table 1). Certainly, these pathologies would have been missed if the scan had been limited to the kidneys, ureters and bladder. It must be acknowledged that the increase in scan extent increases patients’ radiation dose. This was discussed by Denton et al, who reported that the increase in radiation dose is partly offset by the amount of information gained, which may alter subsequent patient management.26 Therefore, despite increased dose rates, it is necessary to consider the bigger picture when evaluating overall patient benefits. However, this does not eliminate or exclude the need to keep the radiation dose as low as reasonably achievable (ALARA) by using an appropriate CT scanning protocol that provides diagnostic images with less radiation dose.
Figure 5. A: NECT image showed ureteral stone with soft-tissue rim sign, B: NECT image revealed moderate perinephric fat stranding.
an oral contrast media (water) in NECT scanning, no harm or disadvantages were experienced by the participants. That is, water provided better demonstration of the gastrointestinal tract, stomach, intestines and urinary bladder, and enabled better visualization of pathological findings. Also, water is relatively cheap, safe and better tolerated by patients than contrast agents containing sodium (eg, gastrografin) or barium sulphate. Further research needs to be conducted with a larger sample to reliably assess the effect of oral contrast media in evaluating patients with flank pain or suspected urolithiasis.
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Radiation Dose Used for NECT Scans Extensive literature has been published in regard to the radiation dose resulting from NECT compared with that patients receive from IVU exams. The increase in radiation dose from CT scanning compared with an IVU procedure is partly offset by the risks associated with IV contrast media used for an IVU and the amount of information gained from CT that would not be obtained from IVU and may alter subsequent patient management.26 Therefore, although the dose rate used is important, it is necessary to look at the bigger picture when comparing these techniques. The current study did not attempt to compare the radiation dose between CT and IVU. Rather, the intent was to design a scanning protocol for this patient group, ensuring the dose delivered to the patient was no more than the dose used during routine abdominal CT scans. This was achieved by designing an appropriate scanning protocol with the radiologists’ assistance, standardizing the scanning protocol throughout the study, using careful scanning technique and manipulating scanning parameters (kV and mAs) appropriately to ensure that the radiation dose was as low as reasonably achievable. Radiation dose
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from CT varies greatly depending on the scanning protocol and scanner geometry. In this study, the average estimated radiation dose to the patient was 11.89 mGy. This is comparable to a previous study reported by Heidenreich et al in which the radiation dose varied between 1 and 4 rad (10 to 40 mGy) for body scans.8 However, additional studies are required on radiation burden and the most appropriate scanning protocol to reduce exposure. Implications for Radiology Practice The findings of the current study have great clinical significance. NECT enables the assessment of the urinary and nonurinary causes of flank pain. In addition, NECT offers the following advantages, which have been confirmed by the current study and numerous independent investigators: ■ Elimination of risks associated with IV contrast agents. ■ High sensitivity in depicting calculi, regardless of the stones’ composition. ■ Ability to assess the location, size, ancillary signs and density of stones. Furthermore, NECT provides faster data acquisition and is relatively cheap. However, it is not clear whether the introduction of oral contrast increases study sensitivity. Yet, as mentioned earlier, the use of water as an oral contrast medium with NECT is strongly recommended by the radiologists who participated in the current study. Further Research This study showed that NECT scans facilitate more accurate assessments in the diagnosis of acute flank pain and urolithiasis. However, further research would be beneficial to: ■ Determine optimum CT windowing levels to accurately assess the size of stones through comparison with actual stone measurements. ■ Identify the most effective HU for assessing stone composition and type. ■ Further investigate the advantages of an extended scan protocol (eg, evaluate the clinical advantages of assessing fatty infiltration of the liver using HU for all referred patients. ■ Test the use of water as an oral contrast agent with a large sample of participants. These initiatives will help radiologists provide referring physicians with detailed reports, including an accurate overview of stone size and composition, as well as an assessment of the liver. Further knowledge in these areas will ensure that patients receive an
accurate diagnosis and appropriate medical management and follow-up. Limitations of the Study The following limitations of the study need to be acknowledged. First, because of a shortage of radiologists and time limitations, each case was reported once, which may increase the possibility of bias. Second, the study was carried out using a single-slice CT scanner that may have lower spatial resolution than multislice CT and affect depiction of tiny pathology. Despite these minor limitations, the study produced useful data and enabled the researchers to make recommendations about further research.
Conclusion The current study results are consistent with previous research on the usefulness of NECT in evaluating urinary and nonurinary tract related pathologies in patients with flank pain, suspected urolithiasis or both. However, this study builds on previous studies in a number of ways. First, the current study scanning protocol enabled the depiction of 1 mm stones and other, immeasurably tiny stones. In addition, the scan extent used in this study enabled more abdominal parenchyma to be covered, which subsequently revealed pathologies that would have been missed if the scan were limited to the kidneys, ureters and bladder. Therefore, the current study showed that NECT scanning is the modality of choice in evaluating flank pain and suspected urolithiasis because of the greater information that can be obtained.
References 1. Nachmann M, Harkaway RC, Summerton SL, et al. Helical CT scanning: the primary imaging modality for acute flank pain. Am J Emerg Med. 2000;18(6):649-652. 2. Tamm E, Silverman PM, Shuman WP. Evaluation of the patient with flank pain and possible ureteral calculus. Radiology. 2003;228(2):319-329. 3. Chowdhury F, Kotwal S, Raghunathan G, Wah TM, Joyce A, Irving HC. Unenhanced multidetector CT (CT KUB) in the initial imaging of suspected acute renal colic: evaluating a new service. Clin Radiol. 2007;62(10):970-977. 4. Rafique MZ, Usman MU, Bari V, Haider Z. Non contrast helical CT scan for acute flank pain: non calculus urinary and extra urinary causes. Pak J Med Sci Q. 2006;22(4):457-460. 5. Noroozian M, Cohan RH, Caoili EM, Cowan NC, Ellis JH. Multislice CT urography: state of the art. Br J Radiol. 2004;77:S74-S86. 6. Ha M, MacDonald RD. Impact of CT scan in patients with first episode of suspected nephrolithiasis. J Emerg Med. 2004;27(3):225-231.
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7. Ege G, Akman H, Kuzucu K, Yildiz S. Acute ureterolithiasis: incidence of secondary signs on unenhanced helical CT and influence on patient management. Clin Radiol. 2003;58(12):990-994. 8. Heidenreich A, Desgrandschamps F, Terrier F. Modern approach of diagnosis and management of acute flank pain: review of all imaging modalities. Eur Urol. 2002;41(4): 351-362. 9. Gottlieb RH, La TC, Erturk EN, et al. CT in detecting urinary tract calculi: influence on patient imaging and clinical outcomes. Radiology. 2002;225(2):441-449. 10. Colistro R, Torreggiani WC, Lyburn ID, et al. Unenhanced helical CT in the investigation of acute flank pain. Clin Radiol. 2002;57(6):435-441. 11. Eshed I, Kornecki A, Rabin A, Elias S, Katz R. Unenhanced spiral CT for the assessment of renal colic. How does limiting the referral base affect the discovery of additional findings not related to urinary tract calculi? Eur J Radiol. 2002;41(1):60-64. 12. Lumerman J, Gershbaum MD, Hines J, Nardi P, Beuchert P, Katz DS. Unenhanced helical computed tomography for the evaluation of suspected renal colic in the adolescent population: a pilot study. Urology. 2001;57(2):342-346. 13. Meagher T, Sukumar VP, Collingwood J, et al. Low dose computed tomography in suspected acute renal colic. Clin Radiol. 2001;56(11):873-876. 14. Chen MY, Zagoria RJ. Can noncontrast helical computed tomography replace intravenous urography for evaluation of patients with acute urinary tract colic. J Emerg Med. 1999;17(2):299-303. 15. Kocakoc E, Bhatt S, Dogra VS. Renal multidetector row CT. Radiol Clin North Am. 2005;43(6):1021-1047. 16. Hofer M. CT Teaching Manual: A Systematic Approach to CT Reading. 3rd ed. New York, NY: Thieme Medical Publishers; 2007:18-20. 17. Memarsadeghi M, Heinz-Peer G, Helbich TH, et al. Unenhanced multi-detector row CT in patients suspected of having urinary stone disease: effect of section width on diagnosis. Radiology. 2005;235(2):530-536. 18. Raby N. The role of CT in acute abdominal pain. Imaging. 2001;13(2):112-123. 19. Thomas B, Hall J. Urolithiasis. Surgery. 2005;23(4):129-133. 20. Sandhu C, Anson KM, Patel U. Urinary tract stones - part I: role of radiological imaging in diagnosis and treatment planning. Clin Radiol. 2003;58(6):415-421. 21. Seeram E. Computed Tomography: Physical Principles, Clinical Applications, and Quality Control. 2nd ed. Sydney, Australia: WB Saunders Co; 2000. 22. Kenney P. CT evaluation of urinary lithiasis. Radiol Clin N Am. 2003;41(5):979-999. 23. Sebastian A, Tait P. Renal imaging. Medicine. 2007;35(7):377-382. 24. Lee JK, Sagel SST, Stanley RJ, Heiken JP. Computed Body Tomography with MRI Correlation. 4th ed. Sydney, Australia: Lippincott Williams & Wilkins; 2006:1242 – 1246.
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25. Sheafor D, Hertzberg BS, Freed KS, et al. Nonenhanced helical CT and US in the emergency evaluation of patients with renal colic: prospective comparison. Radiology. 2000;217(3):792-797. 26. Denton ER, Mackenzie A, Greenwell T, Popert R, Rankin SC. Unenhanced helical CT for renal colic — Is the radiation dose justifiable? Clin Radiol. 1999;54(7):444-447.
Ahmed K Alshamakhi, BSc, is a master’s degree student in medical imaging science at Curtin University of Technology in Perth, Australia. Luke C Barclay, PhD, is a medical imaging sutdent at Curtin University of Technology. Georgia Halkett, PhD, is a senior research fellow in the WA Centre for Cancer and Palliative Care at Curtin University of Technology. Girish Kukade, MD, is head of radiology at the Armed Forces Hospital in the Sultanate of Oman, Dilip Mundhada, MD, Ravi R Uppoor, DMRD and Pradnya Gawai, MD, are specialist radiologists at the AFH in Oman. Mr Alshamakhi would like to thank the government of Oman, represented by the Armed Forces Medical Services, for providing him with the opportunity to complete a master’s degree in Australia. Many thanks to all of the staff in the radiology department and Accident and Emergency and the urology physicians based at the AFH hospital. We are also grateful to Dr Zhongua Sun for his valuable advice. Reprint requests may be sent to the American Society of Radiologic Technologists, Communications Department, 15000 Central Ave SE, Albuquerque, NM 87123-3909, or e-mail
[email protected]. ©2009 by the American Society of Radiologic Technologists.
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