Unenhanced Helical Computed Tomography Research Articles

Ureterolithiasis: can clinical outcome be predicted with unenhanced helical CT?

To evaluate the use of helical computed tomography (CT) without contrast material enhancement for prediction of a favorable outcome in ureterolithiasis. CT studies were reviewed in 69 patients with a single ureteral stone not located at the ureteropelvic junction. CT findings (tissue rim sign, hydronephrosis, perinephric fat stranding, perinephric fluid collections, and thickening of renal fascia) were graded on a scale of 0-3. Stone diameter and renal parenchymal enlargement were also measured. Twenty-two patients had spontaneous passage, 12 did not respond to conservative treatment, and 35 were lost to follow-up. When the latter 35 patients were excluded, perinephric fat stranding (P = .044) and perinephric fluid collections (P = .021) were graded significantly higher in patients with spontaneous stone passage. Mean stone diameter was significantly larger (P < .001) in patients in whom conservative treatment failed (mean, 7.8 mm) than in patients with spontaneous stone passage (mean, 2.9 mm). The presence of a tissue rim sign and the grade of hydronephrosis, renal fascial thickening, and renal parenchymal enlargement were not significantly different between the two groups. In addition to stone size, the degree of perinephric fat stranding and the presence of perinephric fluid collections are useful ancillary signs for help in predicting the likelihood of stone passage.

Initially unresectable hilar cholangiocarcinoma: hepatic regeneration after transarterial embolization.

To assess with volumetric computed tomography (CT) the pattern and extent of hepatic regeneration induced with transarterial embolization of initially unresectable hilar cholangiocarcinoma (Klatskin tumor). In this prospective study, 13 patients (four men, nine women) with hilar cholangiocarcinoma, aged 43-74 years (mean +/- 1 standard deviation, 59.9 years +/- 9.6), underwent preoperative embolization of the right hepatic lobe. Embolization was performed transarterially by using four to 15 embolization coils. Volumetric measurements of the entire liver, left hepatic lobe, and spleen were performed with contrast material-enhanced and unenhanced helical CT before and after embolization in all patients. After right lobe embolization, volumetric helical CT measurements revealed a 2%-33% decrease (mean, 10%) in the volume of the affected right hepatic lobe, an 11%-68% increase (mean, 37%) in the volume of left hepatic lobe parenchyma, and variations in splenic volume of -5% to +28% (mean, +11%). Nine patients underwent extended hepatectomy 27-75 days (mean, 44 days) after embolization. No patient had severe complications due to embolization. In patients with an initially unresectable bilateral Klatskin tumor, right lobar arterial coil embolization results in enlargement of the left hepatic lobe (as verified with volumetric helical CT), thus allowing right hemihepatectomy.

Unenhanced helical CT criteria to differentiate distal ureteral calculi from pelvic phleboliths.

To identify imaging features at unenhanced helical computed tomography (CT) that help differentiate distal ureteral calculi from pelvic phleboliths. Retrospective analysis was performed of 184 pelvic calcifications identified at unenhanced helical CT in 113 patients. The size, shape, and attenuation of each calcification were recorded in addition to the presence of a central lucency and the appearance of the adjacent soft tissues. With profile analysis, a graphic representation was generated of attenuation in each pixel along a line drawn through each calcification. Geometric configuration was seen in eight (21%) calculi but not in any phleboliths. Differences were significant (P < .0001) between the mean attenuation of calculi and that of phleboliths. Among phleboliths, none had a mean attenuation greater than 278 HU, 13 (9%) had a visible central lucency, 31 (21%) had a bifid peak at profile analysis, 30 (21%) had the "comet sign" (adjacent eccentric, tapering soft-tissue mass corresponding to the noncalcified portion of a pelvic vein), and three (2%) had the soft-tissue rim sign (edema of the ureteral wall). Among calculi, none had a central lucency, bifid peak, or comet sign, but 29 (76%) had the soft-tissue rim sign. Analysis of pelvic calcifications at unenhanced helical CT can help differentiate calculi from phleboliths.

THE VALUE OF UNENHANCED HELICAL COMPUTERIZED TOMOGRAPHY IN THE MANAGEMENT OF ACUTE FLANK PAIN

Purpose We developed an algorithm using unenhanced computerized tomography (CT) for the management of acute flank pain and suspected ureteral obstruction. Materials and Methods During a 25-month interval 417 patients with acute flank pain underwent unenhanced helical CT. The final diagnosis was confirmed by additional imaging or clinical followup. For all patients who underwent additional imaging studies the official dictated radiology reports were used to determine whether the studies were recommended based on CT findings. Cases requiring intervention were evaluated to determine whether additional imaging was performed before the procedure. Medical records were reviewed and/or patients were interviewed to document the course of therapy and long-term outcome. Results Unenhanced helical CT diagnosed ureteral stone disease with 95% sensitivity, 98% specificity and 97% accuracy. Of the 38 patients requiring intervention, including nephrostomy catheters in 18, lithotripsy in 3 and ureteroscopic stone extraction in 7, additional imaging (excretory urography) was performed in only 1. Additional imaging studies generated by CT were done in 3 cases in which the dictated reports were indeterminate for ureteral stones, including negative excretory urography in 2 and retrograde urography in 1. In 1 patient in whom CT misdiagnosed a ureteral stone unnecessary retrograde urography revealed the calcification to be a gonadal vein phlebolith. Seven patients with false-negative examinations reported spontaneous stone passage with no complications. Conclusions Unenhanced helical CT accurately determines the presence or absence of ureterolithiasis in patients with acute flank pain. CT precisely identifies stone size and location. When ureterolithiasis is absent, other causes of acute flank pain can be identified. In most cases additional imaging is not required.

Unenhanced helical computed tomography for suspected urinary tract stones: Current state of the art

In an increasing number of hospitals, unenhanced helical computed tomography (CT) has replaced intravenous urography in the evaluation of patients with suspected ureterolithiasis. CT is safe and efficient, and it provides a wealth of diagnostic information including the size, number, and location of stones, the effects of stones on the urinary tract, and alternative diagnoses in patients without stone disease. CT is significantly faster than urography and does not generally require placement of an intravenous line or injection of contrast agent, and consequently there is no risk of contrast reaction. The use of unenhanced helical CT for suspected ureterolithiasis requires careful attention to detail and familiarity with urinary tract anatomy and signs of urinary tract obstruction.

Ureteral calculi in patients with flank pain: correlation of plain radiography with unenhanced helical CT.

To determine the sensitivity and specificity of plain radiography for the detection of ureteral calculi with use of unenhanced helical computed tomography (CT) as the standard of reference. Plain radiographs and helical CT scans of 178 patients with acute flank pain were reviewed retrospectively. Three interpretations of plain radiographs were used: (a) Original reading. This was the report made at the time of the patient's evaluation before the patient underwent CT. (b) Blinded retrospective reading. Each plain radiograph was interpreted without knowledge of the CT findings. (c) Unblinded retrospective reading. The plain radiograph of each patient whose CT scan showed a stone was reviewed with the CT scan. The original reading had a sensitivity of 45% and a specificity of 77% for the detection of ureteral calculi. The blinded retrospective reading had a sensitivity of 59% and a specificity of 71%. The unblinded retrospective reading had a sensitivity of 59% (95% confidence interval: 47%, 70%). Plain radiography is of limited value for aiding the diagnosis of ureteral stones. All patients with acute flank pain for whom radiologic imaging is recommended can directly undergo unenhanced helical CT; plain radiographs need not be obtained first.