Unenhanced CT KUB for urinary colic : It's not just about the stones

Transcription

1 Unenhanced CT KUB for urinary colic : It's not just about the stones Poster No.: C-0762 Congress: ECR 2016 Type: Educational Exhibit Authors: P. Jagmohan, S. Dhanda, B. ang, S. T. Quek; SINGAPORE/SG Keywords: Acute, Diagnostic procedure, CT, Abdomen DOI: /ecr2016/C-0762 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 54

2 Learning objectives 1. To recognize the mimics of urinary colic on imaging. 2. To illustrate unrelated but significant incidental findings 3. To highlight review areas and blind spots and establish a systematic approach to improve detection of alternate diagnosis and unsuspected additional findings Background Unenhanced CT KUB is increasingly becoming the imaging mainstay for diagnosis of suspected urinary colic. It is a rapid and accurate test that does not require contrast or bowel preparation. CT KUB has a high sensitivity (>95%) and specificity (>96%) for the detection of urinary calculi and is superior to intravenous urography and ultrasound [1-3].Another advantage of CT KUB is its ability to detect alternate diagnosis for flank pain. Symptoms of numerous diseases can mimic renal colic because receptors of many visceral organs and body wall can transmit the sensation through shared pain fibres. Upto half to one third of studies performed for suspected urinary calculi are negative with alternate conditions mimicking urinary colic seen in 10-29% cases [1,4-6]. Early recognition of these alternate diseases is key to institution of correct therapy. Apart from calculi and mimics of urinary colic, often incidental significant findings affecting a wide range of organs and warranting further work up can be seen even on an unenhanced CT KUB. While detection of urinary calculi or other causes of acute flank pain is the focus of these studies it is also important to detect these incidental but significant findings many of which are clinically unsuspected. Important incidental findings requiring further follow up were seen in upto 12.7 % of CT studies done for suspected renal colic and were more prevalent in older patients in one study [7]. Another study evaluating non contrast CT studies for renal stones in the emergency department found incidental findings in 45% of scans, half of which were deemed to be of moderate to serious concern. Additionally only 21% of the incidental findings were documented [8]. Page 2 of 54

3 Findings and procedure details We reviewed the non-calculi related imaging findings in patients who underwent unenhanced CT KUB at our hospital. Of these a significant number of patients had alternate diagnoses for acute flank pain with gastrointestinal and gynecologic conditions being the most common clinical mimics. Additionally a gamut of incidental lesions of varying clinical significance were seen covering a range from pathologies from the lung bases to the pelvis. We present a system wise review of the alternate diagnosis and significant incidentals in CT KUB studies done at our institution and highlight the blind spots and review areas in an effort to develop a systematic approach towards reporting these studies. NON CALCULI RELATED URINARY CONDITIONS : A range of urinary disorders especially those causing hydronephrosis can mimic urinary colic. Pyelonephritis is an important alternate cause for acute flank pain. Moderate - severe pyelonephritis can manifest as asymmetric nephromegaly and perirenal stranding ( fig 1), findings that can be indistinguishable from a recently passed calculus. The diagnosis can be confirmed by urinalysis and a contrast enhanced CT which demonstrates typical features such as a striated appearance and wedge shaped hypodensities. More complex forms such as emphysematous pyelonephritis ( fig2 ) and complications such as renal/perirenal abscesses can also be seen. Page 3 of 54

4 Fig. 1: 59 year old female with left flank pain. CT KUB (axial and coronal) showed an enlarged left kidney with adjacent stranding, fascial thickening and minimal fluid in keeping with pyelonephritis. Urinalysis confirmed findings of urinary tract infection. Page 4 of 54

5 Fig. 2: A middle aged patient with acute left flank pain. CT KUB ( axial and coronal) shows features of emphysematous pyelonephritis. Other alternate causes seen on CT KUB include congenital retrocaval ureter (fig 3), megaloureter and ureteral strictures. Sometimes urinary neoplasms may present with hematuria and flank pain mimicking a calculus disease ( fig 4). Fig. 3: A 47 year old female with right loin pain. CT KUB shows tiny right calyceal calculi and right hydroureteronephrosis (A,B) with medial deviation and abrupt tapering of the right ureter (indicated by arrows) at L4 (B, C). IVU confirmed diagnosis of retrocaval ureter (arrow) (D). Page 5 of 54

6 Fig. 4: 47 year old male with right loin pain and a lobulated soft tissue mass ( arrows) seen in relation to the anterosuperior surface of the urinary bladder on CT KUB ( A,B) ; also seen on subsequent CECT(C,D). Cystoscopy showed an extrinsic mass at the bladder dome with normal mucosa suggesting urachal carcinoma Incidental findings affecting the urinary system are commonly seen especially in older patients with the commonest being cysts. Congenital anomalies such as horseshoe kidney and duplication anomalies may be seen as an incidental finding ( fig 5,6). Page 6 of 54

7 Fig. 5: 67 year old female with right loin pain. CT KUB showed a horseshoe kidney ( arrow indicating site of fusion) with no urinary calculi or hydroureteronephrosis Page 7 of 54

8 Fig. 6: 57 year old male with right loin pain. CT KUB showed a duplex kidney on the right (arrows indicate the two pelves and ureters). No urinary calculi or hydroureteronephrosis was seen Of note are the incidentally detected renal masses which may be seen as focal renal contour deformities, focal areas of differential attenuation and complex cystic lesions. Indeterminate features within an incidentally detected renal masses such as attenuation between HU ( fig 7) or those containing thickened walls/septations/ calcifications and mural nodules would warrant further imaging workup. Page 8 of 54

9 Fig. 7: A 47 year old male with an incidental soft tissue attenuation ( 48HU) mass in the mid pole of left kidney (A), shown on US (B,C) to be a heterogenous vascular mass. CECT (D) showed a heterogeneously enhancing solid mass that was resected and was a renal cell carcinoma Masses containing fat and attenuation less than 20 HU or greater than 70 HU are usually benign ( fig 8, 9) [9, 10] Page 9 of 54

10 Fig. 8: 67 year old female with right flank pain and an incidental well defined low density ovoid lesion (11HU) in the lower pole of the left kidney ( arrow), confirmed by ultrasound to be a simple cyst Page 10 of 54

11 Fig. 9: 76 year old male with prior left nephrectomy and an incidental 1.6 cm fat density mass in the mid pole right kidney (arrow) in keeping with an angiomyolipoma ACR recommendations for incidentally detected renal masses on low dose unenhanced CT [10] are : 1) Incidentally detected masses with homogenous low attenuation ( 0-20HU) and no septa/wall thickening/ thick calcification/nodularity should be interpreted as simple cysts 2) A small renal mass ( <3cm), homogenous and >70 HU can be diagnosed as a benign hyperattenuating cyst ( Bosniak category II) GYNECOLOGICAL CONDITIONS : Page 11 of 54

12 Gynecological conditions are one of the most commonly seen lesions on CT KUB, both as mimics of urinary colic or as incidental findings. These include adnexal masses such as ovarian cysts, ovarian torsion, endometriomas, dermoids and ovarian neoplasms ( fig 10). High density contents within ovarian cystic lesions suggest the diagnosis of hemorrhagic cysts and endometriomas while the presence of fat, calcification, teeth, or fat-fluid levels confirm the diagnosis of dermoid. Further characterization of complex adnexal masses requires ultrasound or MRI. Fig. 10: A 45 year old female with right flank pain and large pelvic mass on CT KUB ( arrow) (A), this was confirmed to be a right adnexal solid mass on US (B) abutting the uterus. MRI showed a predominantly T2 hypointense (C) heterogeneously enhancing right adnexal mass ( arrows) abutting the uterus ; surgery confirmed diagnosis of fibrothecoma Pelvic inflammatory disease often presents as flank and lower abdominal pain and is seen on the non-contrast study as complex cystic masses associated with pelvic inflammatory changes such as fascial thickening, fat stranding and pelvic fluid/ collections. Fibroids are the commonest uterocervical masses ( fig 11); most of these are seen as incidental findings with degenerating or torsed fibroids presenting as acute abdomen and Page 12 of 54

13 incidental findings. Additionally large adnexal and uterocervical masses also cause mass effect on the urinary tract and mimic urinary symptoms. Fig. 11: A 45 year old female with left lower abdominal pain. CT KUB showed a homogenous soft tissue attenuation mass along the left lateral aspect of the uterus (arrow) confirmed as a subserosal fibroid on ultrasound. Also note the calcific fibroid on the right. GASTROINTESTINAL CONDITIONS: Gastrointestinal conditions are a common cause of acute flank pain. Acute appendicitis and diverticulitis of the colon are frequently seen in studies performed for suspected urinary colic. While gastrointestinal conditions are best evaluated on contrast enhanced studies, unenhanced CT can also provide diagnostic information. CT diagnosis of acute appendicitis is based on the presence of a dilated, thick-walled, blind-ending, tubular structure with a diameter exceeding 6 mm with or without an appendicolith with periappendiceal inflammation ( fig 12). Paucity of abdominal fat may make identification of a mildly thickened appendix on a non-contrast study difficult ; Page 13 of 54

14 however the presence of inflammatory changes in the right iliac fossa especially in a study negative for urinary calculi should alert the radiologist to this possibility; indeed given how often appendicitis is seen in studies performed for urinary calculi the appendix should be actively searched for in every CT KUB. Fig. 12: 43 year old male with right loin pain. CT KUB showed acute appendicitis with a thickened appendix (arrows) and periappendiceal inflammatory changes; confirmed on surgery Diverticulitis is another common cause of flank pain especially in elderly patients. It typically manifests as left-sided lower abdominal pain, as the left and sigmoid colon are predominantly affected. Less often, the right colon and cecum may be involved. CT findings of acute diverticulitis consist of asymmetric or circumferential colonic wall thickening associated with focal pericolic fat stranding seen against a background of diverticulosis (fig 13). Page 14 of 54

15 Fig. 13: An 80 year old female with previous history of urolithiasis presenting with right flank pain. CT KUB axial (right) and coronal ( left) images shows right colonic diverticulitis with mild right colonic thickening and prominent pericolonic stranding ( arrows) against a background of diverticulosis Other gastrointestinal causes mimicking urinary colic include bowel perforation (fig 14), enterocolitis and intussusception. Page 15 of 54

16 Fig. 14: 56 year old male with previous history of urolithiasis and right central abdominal pain. CT KUB showed pneumoperitoneum with locules adjacent to gastric antrum with associated perigastric fat stranding at the distal stomach ( arrow) suggesting possible gastric perforation (confirmed on surgery). Gallstones and left renal calculi were also seen on CT ( not shown) Commonly seen incidental bowel findings such as colonic and duodenal diverticulae and hiatus hernia are usually of little significance in asymptomatic patients. A clinically significant and sometimes missed finding is the incidentally detected bowel mass which may be benign or malignant. The bowel is a potential blind spot on CT KUB and as such small masses may sometimes be difficult to detect on these studies, given the absence of contrast and bowel preparation and often suboptimal bowel distension. Presence of fat within the mass can help characterize it on a non contrast study ( fig 15) ; most other masses would require further workup Page 16 of 54

17 Fig. 15: A 56 year old male patient with an incidentally detected duodenal lipoma on CT KUB ( arrow). Also note the fatty liver. CONDITIONS AFFECTING APPENDAGES : THE MESENTERY, OMENTUM AND EPIPLOIC Epiploic appendagitis, mesenteric lymphadenitis, omental infarction and mesenteric panniculitis are some conditions presenting with acute flank pain. Epiploic appendagitis is caused by torsion or venous thrombosis of the epiploic appendages and is more common in middle-aged men. The typical CT appearance is that of an ovoid pericolic lesion of fat attenuation with a hyperdense rim, sometimes with a central dot representing the thrombosed vessel ( fig 16). Page 17 of 54

18 Fig. 16: 38 year old male with left loin pain. CT KUB showed no urinary calculi. Focal fat stranding surrounded by a thin ring in the left hemipelvis (arrows) seen adjacent to the sigmoid colon in keeping with epiploic appendagitis Mesenteric lymphadenitis usually affects young patients and is seen on CT as a cluster of mildly enlarged ileocolic nodes often associated with wall thickening of the terminal ileum and cecum. Omental infarction is an uncommon condition, more common in obese patients and is seen on CT as a heterogeneous fat containing omental mass usually in the right lower quadrant with associated stranding and free fluid. Mesenteric panniculitis is often seen as an incidental finding but may sometimes present with acute abdomen. CT shows a misty mesentery appearance usually at the mesenteric root with a thin pseudocapsule, mildly enlarged nodes and a halo of fat surrounding the nodes and vessels ( fig 17). Page 18 of 54

19 Fig. 17: 42 year old male with left flank pain. CT KUB shows mesenteric panniculitis with a "misty appearance" of the mesentery and halo of spared fat around the nodes (arrows). Significant incidental findings include mesenteric lymphadenopathy, mesenteric and omental masses. HEPATOBILIARY AND PANCREATIC CONDITIONS : Inflammatory conditions affecting the liver, biliary system and pancreas such as hepatic abscesses, cholecystitis and pancreatitis may mimic urinary colic. While these are better evaluated on a contrast enhanced study, a non-contrast study may provide diagnostic information such as distended gallbladder, wall thickening, calculi, pericholecystic stranding and fluid collections in acute cholecystitis ( fig 18). Biliary dilatation and choledocholithiasis could provide a clue to cholangitis. Cholelithiasis and choledocholithiasis, especially the former are also often seen as incidental findings ( fig 19). Page 19 of 54

20 Fig. 18: 60 year old female with right flank pain. CT KUB ( axial and coronal) showed marked inflammatory changes ( arrows) around the gall bladder in keeping with acute cholecystitis. This was confirmed on surgery Page 20 of 54

21 Fig. 19: 54 year old male who underwent CT KUB for renal colic which showed renal calculi. Incidental subcentimeter calculus was seen in the distal CBD (arrow). Subsequently the patient underwent ECRP, stone extraction and sphincterectomy A hepatic abscess may be seen as non-specific rounded hypodensity ( fig 20) however clustered septated hypodensity in the appropriate clinical context or presence of air are useful signs. Page 21 of 54

22 Fig. 20: 64 year old male with type II diabetes and previous history of urolithiasis and hepatic abscess, now presenting with right central abdominal pain. CT KUB showed a subcentimeter right distal ureteric calculus ( not shown) and few hepatic soft tissue attenuation hypodensities measuring upto 2 cm (arrow), seen on ultrasound as small hypoechoic lesions. The patient was treated for hepatic abscesses and follow up contrast enhanced CT showed interval resolution ( not shown) Non contrast findings of acute pancreatitis include pancreatic enlargement, peripancreatic fat stranding, pararenal fascial thickening, pancreatic and peripancreatic collections ( fig 21). Page 22 of 54

23 Fig. 21: 61 year old female with right loin and lower quadrant pain. CT KUB showed bulky pancreatic body and tail with surrounding fat stranding. Lab tests confirmed acute pancreatitis Biliary calculi, fatty liver Fig. 15 on page 41 and focal hepatic lesions are amongst the most frequent incidental findings seen on non- contrast studies. Other incidental findings include biliary dilatation, gall bladder and pancreatic masses/ cysts. While lack of contrast limits detection of small masses ; a deformity of the contour of the pancreas and focal areas of differential attenuation are useful signs for pancreatic masses ( fig 22). Page 23 of 54

24 Fig. 22: 60 year old man with incidentally detected mass in the body of the pancreas ( arrow) with multiple hypodensities and enlarged peripancreatic and retroperitoneal nodes on CT KUB ( right) in keeping with a pancreatic primary with hepatic metastases, subsequently evaluated on contrast enhanced CT ( left) CA19-9 was elevated and liver nodule biopsy was done for confirmation. Similarly soft tissue density within the gall bladder, irregularity of the gall bladder outline and hypodense changes in the adjacent liver provide clues to a gall bladder mass which are often seen in the setting of calculus disease ( fig 23). Page 24 of 54

25 Fig. 23: 58 year old male with suspected urolithiasis. CT KUB showed a grossly distended gallbladder with soft tissue density contents and small hypodensities in the adjacent liver ( arrow) ( A,B). US showed nodular slightly hyperechoic lesion with sparse vascularity filling most of the gallbladder (C) and hypoechoic changes in the liver at the gall bladder fossa (D). CECT ( E) and post contrast axial MRI (F) showed a gallbladder mass in keeping with a primary gall bladder malignancy with adjacent hepatic involvement ( arrows). Majority of the incidental hepatic and pancreatic lesions are benign. According to the ACR Incidental Findings Committee recommendations [10,11]: 1. In low-risk and average-risk patients, sharply marginated, low-attenuation (< 20 HU) solitary or multiple hepatic masses may typically not need further evaluation. 2. Small, solitary hepatic masses 1.5 cm that are not cystic and are discovered on unenhanced or standard-dose or low-dose scans in low-risk and average-risk patients may typically not need further evaluation. 3. For pancreatic cystic masses 1-2 cm follow up preferably with MRI can be done in 1 year. Stability over 1 year is highly suggestive of a benign lesion and may eliminate the Page 25 of 54

26 need for follow-up imaging. For larger lesions management is based on size and imaging features on studies preferably MRI/MRCP 4. No additional work up is recommended for gallstones with no associated ductal dilation, mass, or clinical symptoms ADRENAL LESIONS : An incidental adrenal mass or an adrenal incidentaloma is a common finding on crosssectional imaging examination. Incidental adrenal masses are seen in approximately 3% to 7% of the adult population with the most frequent pathology being a nonhyperfunctioning adenoma (fig 24). Indeed in a patient with no known malignancy the vast majority of adrenal incidentalomas are benign. Even in a patient with cancer an incidentally discovered adrenal mass is more likely benign. Other unsuspected adrenal lesions include primary adrenal cancers, adrenal hyperplasia (fig 25) and metastases. Page 26 of 54

27 Fig. 24: 51 year old male with left renal calculi ( not shown) and incidental 1.5 cm well defined hypodense ( -6 HU) nodule along the medial limb of the left adrenal gland in keeping with a lipid-rich adenoma. Page 27 of 54

28 Fig. 25: 56 year old male with incidental detection of bilateral enlarged adrenals on CT KUB (arrows), incidental renal cysts were also seen. CT adrenals (not shown) confirmed bulky nodular appearance of both adrenals with no dominant nodule. Patient underwent further workup including venous sampling and intravenous saline suppression test and diagnosis of primary hyperaldosteronism was made Imaging characterisation of incidental adrenal lesions is done with CT or MRI adrenal studies with the goal of differentiating between the benign "leave- alone" mass from a mass needing treatment. An unenhanced CT may still provide useful information about adrenal incidentalomas, in particular identifying benign lesions and those needing further work up. The ACR Incidental Findings Committee incidentalomas on unenhanced CT [10] are : recommendations for adrenal 1. If the mean attenuation of an adrenal mass is less than 10 HU on a low-dose CT examination, it is likely to be a benign adenoma. 2. If a lesion is > 10 HU and 1 to 4 cm in an asymptomatic patient without cancer, 1-year follow-up CT or MRI may be considered, if no prior studies for comparison are available. Prior examinations that show stability for 1 year can eliminate the need for further workup Page 28 of 54

29 3. For adrenal masses more than 4 cm, dedicated adrenal MRI or CT should be considered MISCELLANEOUS CONDITIONS : Vascular conditions may be difficult to diagnose on an unenhanced CT; however these can be potentially life threatening or warranting further work up. Acute aortic conditions for eg. ruptured abdominal aortic aneurysm and aortic dissection ; and spontaneous intraperitoneal or retroperitoneal hemorrhage can mimic acute flank pain. Aortic aneurysms can also be seen as incidental findings ( fig 26) and these should be reported so that appropriate follow up or management, usually based on size can be done [12]. Fig. 26: 69 year old male with an incidental saccular soft tissue mass along the left border of the thoracic aorta on CT KUB ( axial A,coronal B) ( arrows). CT angiogram ( axial C, coronal D) showed a focal saccular outpouching along the left side of the descending aorta with eccentric mural thrombus suspicious for a mycotic aneurysm Musculoskeletal conditions can both mimic urinary colic or represent incidental findings. These include spinal fractures which may be seen in the elderly population Page 29 of 54

30 without a history of significant trauma, spondylolisthesis, psoas hematoma /abscess, metastases and avascular necrosis of the femoral head. A careful analysis of the bone window should always be done especially in the older age group. THORACIC CONDITIONS : The lower sections of the thorax and lung bases are usually included in a CT KUB and is one of the potential blind spots. Incidental significant findings that were worked up further included lung masses/nodules ( fig 27), breast mass ( fig 28) and interstitial lung disease. Given the potential clinical significance of pulmonary nodules these should always be searched for. Fig. 27: 57 year old male patient with right renal colic and an incidentally detected soft tissue density mass right lung base on CT KUB (A, arrow). Contrast enhanced CT thorax showed a suspicious right posterobasal 2.6 cm mass abutting posterior pleural surface (B,C). This was a non-small cell carcinoma and patient underwent right lower lobectomy Page 30 of 54

31 Fig. 28: 52 year old female with incidentally detected mass in the right inner breast mass ( A, arrow). This was confirmed on mammography (B, right craniocaudal view) and US (C) which showed a suspicious mass. US guided 14 G core needle biopsy was done and showed invasive carcinoma. Patient underwent right mastectomy and axillary clearance and final histology was invasive ductal carcinoma, NOS, in a background of encapsulated papillary carcinoma A systematic approach to alternate diagnosis and incidental findings on CT KUB: The clinical notes and laboratory tests should be reviewed. The initial radiological assessment focuses on the urinary tract firstly for identification of calculi and hydroureteronephrosis ; and then for other non calculi related urinary mimics. If the study is negative for these a careful search should be made for alternate diagnosis that can explain the patient's symptoms : most common amongst these are gastrointestinal and gynecological causes and key review areas include appendix and adnexa. Virtually any organ can mimic urinary colic and while most of the conditions mimicking colic are better evaluated on a contrast enhanced study, a non-contrast study can also provide diagnostic information. Regional inflammatory changes such as fat stranding, fascial thickening and fluid collections are useful localizing clues to the underlying organ involvement on a non- contrast study. Additionally acute conditions involving other organs systems and urinary calculi can co- exist. Page 31 of 54

32 Incidental findings are seen in a significant number of unenhanced abdominal CT studies done for urinary calculi, again affecting virtually all organs. Key blind areas that we encountered include bowel, thoracic bases and bones as well as subtle hypodense lesions involving the solid organs. Review of the coronal reformats and lung and bone windows should be performed and changing the window settings ( for eg reviewing the liver at a liver window setting) is useful. Recommendations by bodies such as ACR [10,11, 12] provide useful information on management of incidental findings on unenhanced CT. While majority of the incidental findings are benign, the significant findings warranting further work up or management should be brought to the clinician's notice. Images for this section: Fig. 1: 59 year old female with left flank pain. CT KUB (axial and coronal) showed an enlarged left kidney with adjacent stranding, fascial thickening and minimal fluid in keeping with pyelonephritis. Urinalysis confirmed findings of urinary tract infection. Page 32 of 54

33 Fig. 2: A middle aged patient with acute left flank pain. CT KUB ( axial and coronal) shows features of emphysematous pyelonephritis. Fig. 3: A 47 year old female with right loin pain. CT KUB shows tiny right calyceal calculi and right hydroureteronephrosis (A,B) with medial deviation and abrupt tapering of the Page 33 of 54

34 right ureter (indicated by arrows) at L4 (B, C). IVU confirmed diagnosis of retrocaval ureter (arrow) (D). Fig. 4: 47 year old male with right loin pain and a lobulated soft tissue mass ( arrows) seen in relation to the anterosuperior surface of the urinary bladder on CT KUB ( A,B) ; also seen on subsequent CECT(C,D). Cystoscopy showed an extrinsic mass at the bladder dome with normal mucosa suggesting urachal carcinoma Page 34 of 54

35 Fig. 5: 67 year old female with right loin pain. CT KUB showed a horseshoe kidney ( arrow indicating site of fusion) with no urinary calculi or hydroureteronephrosis Page 35 of 54

36 Fig. 6: 57 year old male with right loin pain. CT KUB showed a duplex kidney on the right (arrows indicate the two pelves and ureters). No urinary calculi or hydroureteronephrosis was seen Page 36 of 54

37 Fig. 7: A 47 year old male with an incidental soft tissue attenuation ( 48HU) mass in the mid pole of left kidney (A), shown on US (B,C) to be a heterogenous vascular mass. CECT (D) showed a heterogeneously enhancing solid mass that was resected and was a renal cell carcinoma Fig. 8: 67 year old female with right flank pain and an incidental well defined low density ovoid lesion (11HU) in the lower pole of the left kidney ( arrow), confirmed by ultrasound to be a simple cyst Page 37 of 54

38 Fig. 9: 76 year old male with prior left nephrectomy and an incidental 1.6 cm fat density mass in the mid pole right kidney (arrow) in keeping with an angiomyolipoma Page 38 of 54

39 Fig. 10: A 45 year old female with right flank pain and large pelvic mass on CT KUB ( arrow) (A), this was confirmed to be a right adnexal solid mass on US (B) abutting the uterus. MRI showed a predominantly T2 hypointense (C) heterogeneously enhancing right adnexal mass ( arrows) abutting the uterus ; surgery confirmed diagnosis of fibrothecoma Page 39 of 54

40 Fig. 11: A 45 year old female with left lower abdominal pain. CT KUB showed a homogenous soft tissue attenuation mass along the left lateral aspect of the uterus (arrow) confirmed as a subserosal fibroid on ultrasound. Also note the calcific fibroid on the right. Fig. 12: 43 year old male with right loin pain. CT KUB showed acute appendicitis with a thickened appendix (arrows) and periappendiceal inflammatory changes; confirmed on surgery Page 40 of 54

41 Fig. 14: 56 year old male with previous history of urolithiasis and right central abdominal pain. CT KUB showed pneumoperitoneum with locules adjacent to gastric antrum with associated perigastric fat stranding at the distal stomach ( arrow) suggesting possible gastric perforation (confirmed on surgery). Gallstones and left renal calculi were also seen on CT ( not shown) Page 41 of 54

42 Fig. 15: A 56 year old male patient with an incidentally detected duodenal lipoma on CT KUB ( arrow). Also note the fatty liver. Fig. 16: 38 year old male with left loin pain. CT KUB showed no urinary calculi. Focal fat stranding surrounded by a thin ring in the left hemipelvis (arrows) seen adjacent to the sigmoid colon in keeping with epiploic appendagitis Page 42 of 54

43 Fig. 17: 42 year old male with left flank pain. CT KUB shows mesenteric panniculitis with a "misty appearance" of the mesentery and halo of spared fat around the nodes (arrows). Page 43 of 54

44 Fig. 18: 60 year old female with right flank pain. CT KUB ( axial and coronal) showed marked inflammatory changes ( arrows) around the gall bladder in keeping with acute cholecystitis. This was confirmed on surgery Fig. 19: 54 year old male who underwent CT KUB for renal colic which showed renal calculi. Incidental subcentimeter calculus was seen in the distal CBD (arrow). Subsequently the patient underwent ECRP, stone extraction and sphincterectomy Page 44 of 54

45 Fig. 20: 64 year old male with type II diabetes and previous history of urolithiasis and hepatic abscess, now presenting with right central abdominal pain. CT KUB showed a subcentimeter right distal ureteric calculus ( not shown) and few hepatic soft tissue attenuation hypodensities measuring upto 2 cm (arrow), seen on ultrasound as small hypoechoic lesions. The patient was treated for hepatic abscesses and follow up contrast enhanced CT showed interval resolution ( not shown) Page 45 of 54

46 Fig. 21: 61 year old female with right loin and lower quadrant pain. CT KUB showed bulky pancreatic body and tail with surrounding fat stranding. Lab tests confirmed acute pancreatitis Page 46 of 54

47 Fig. 22: 60 year old man with incidentally detected mass in the body of the pancreas ( arrow) with multiple hypodensities and enlarged peripancreatic and retroperitoneal nodes on CT KUB ( right) in keeping with a pancreatic primary with hepatic metastases, subsequently evaluated on contrast enhanced CT ( left) CA19-9 was elevated and liver nodule biopsy was done for confirmation. Page 47 of 54

48 Fig. 23: 58 year old male with suspected urolithiasis. CT KUB showed a grossly distended gallbladder with soft tissue density contents and small hypodensities in the adjacent liver ( arrow) ( A,B). US showed nodular slightly hyperechoic lesion with sparse vascularity filling most of the gallbladder (C) and hypoechoic changes in the liver at the gall bladder fossa (D). CECT ( E) and post contrast axial MRI (F) showed a gallbladder mass in keeping with a primary gall bladder malignancy with adjacent hepatic involvement ( arrows). Fig. 24: 51 year old male with left renal calculi ( not shown) and incidental 1.5 cm well defined hypodense ( -6 HU) nodule along the medial limb of the left adrenal gland in keeping with a lipid-rich adenoma. Page 48 of 54

49 Fig. 25: 56 year old male with incidental detection of bilateral enlarged adrenals on CT KUB (arrows), incidental renal cysts were also seen. CT adrenals (not shown) confirmed bulky nodular appearance of both adrenals with no dominant nodule. Patient underwent further workup including venous sampling and intravenous saline suppression test and diagnosis of primary hyperaldosteronism was made Page 49 of 54

50 Fig. 26: 69 year old male with an incidental saccular soft tissue mass along the left border of the thoracic aorta on CT KUB ( axial A,coronal B) ( arrows). CT angiogram ( axial C, coronal D) showed a focal saccular outpouching along the left side of the descending aorta with eccentric mural thrombus suspicious for a mycotic aneurysm Fig. 27: 57 year old male patient with right renal colic and an incidentally detected soft tissue density mass right lung base on CT KUB (A, arrow). Contrast enhanced CT thorax showed a suspicious right posterobasal 2.6 cm mass abutting posterior pleural surface (B,C). This was a non-small cell carcinoma and patient underwent right lower lobectomy Page 50 of 54

51 Fig. 28: 52 year old female with incidentally detected mass in the right inner breast mass ( A, arrow). This was confirmed on mammography (B, right craniocaudal view) and US (C) which showed a suspicious mass. US guided 14 G core needle biopsy was done and showed invasive carcinoma. Patient underwent right mastectomy and axillary clearance and final histology was invasive ductal carcinoma, NOS, in a background of encapsulated papillary carcinoma Page 51 of 54

52 Fig. 13: An 80 year old female with previous history of urolithiasis presenting with right flank pain. CT KUB axial (right) and coronal ( left) images shows right colonic diverticulitis with mild right colonic thickening and prominent pericolonic stranding ( arrows) against a background of diverticulosis Page 52 of 54

53 Conclusion CT KUB is increasingly becoming the investigation of choice for the imaging of urinary calculi. However numerous diseases affecting a wide range of organs can have similar clinical features. Indeed non calculi related pathologies are commonly seen on CT KUB studies, some of which are potentially life threatening. Hence it is essential for radiologists to look out beyond stones - both for the expected alternates and the unexpected significant incidentals. A systematic approach towards these unenhanced studies would aid in detection of both; thus facilitating institution of timely therapy and appropriate follow up. Personal information References References : 1. Smith RC, Rosenfield AT, Choe KA. Acute flank pain: comparison of non -contrast enhanced computerized tomography and intravenous pyelography. Radiology 1995, 194: Yilmaez S, Sindel T, Arsalan G. Comparison of spiral CT, US and IVU in detection of ureteral calculi. Eur Radiol 1998, 8: Spencer BA, Dretler PS. Helical CT and ureteric colic. Urol Clin North Amer 2000, 27: Katz DS, Scheer M, Lumerman JH, et al. Unenhanced helical computed tomography for suspected renal colic: experience with 1000 consecutive examinations. Urology 2000; 56: Hoppe H, Studer R, Kessler TM, et al. Alternate or additional findings to stone disease on unenhanced computerized tomography for acute flank pain can impact management. J Urol 2006; 175: Rucker CM, Menias CO, Bhalla S. Mimics of renal colic : alternative diagnosis at unenhanced helical CT. Radiographics 2004; 24:S11-S33 Page 53 of 54

54 7. Samim M, Goss S, Weinreb J, Moore C. Incidental findings on CT for suspected renal colic in emergency department patients: prevalence and types in 5,383 consecutive examinations. J Am Coll Radiol 2015; 12: Messersmith WA, Brown DF, Barry MJ. The prevalence and implications of incidental findings on ED abdominal CT scans. Am J Emerg Med 2001; 19: O'Connor SD, Pickhardt PJ, Kim DH, Oliva MR, Silverman SG. Incidental findings of renal masses at unenhanced CT: prevalence and analysis of features of guiding management. AJR 2011; 197: Berland LL, Silverman SG, Gore RM, et al. Managing incidental findings on abdominal CT: white paper of the ACR incidental findings committee. J Am Coll Radiol 2010; 7: Sebastian S et al. Managing incidental findings on abdominal and pelvic CT and MRI, Part 4: white paper of the ACR Incidental Findings Committee II on gallbladder and biliary findings. J Am Coll Radiol.2013 ;10 : Khosa F et al. Managing incidental findings on abdominal and pelvic CT and MRI, part 2: white paper of the ACR Incidental finding committee II on vascular findings. J Am Coll Radiol 2013; 10: Page 54 of 54