Unenhanced CT scanning in acute flank pain: value of secondary signs of ureteral obstruction

To determine the value of secondary signs of ureteral obstruction on helical unenhanced CT in diagnosing or excluding ureteral stone disease. Over a period of 15 months, we prospectively analysed the CT scans of 283 patients with acute flank pain for the presence of ureteral stones and associated signs of ureteral obstruction. 105 patients had no confirmatory imaging studies or surgery and were unable to be contacted for follow up .These were excluded from the study. In the remaining 178 patients confirmatory data were availabe and thus were included in the study. Ureteral stone disease was confirmed to be present in 114 patients and absent in 64 patients. For each patient, we determined the presence or absence of ureteral stone, ureteral or collecting system dilatation, perinephric stranding, and renal parenchymal thickening. We also noted the presence or absence of the [" tissue rim" sign] surrounding ureteral stones and extraurinary calcifications. Hydroureter was the sign with the highest sensitivity [92%] and highest specificity [92%], While hydroureter had the highest specificity [95%] and highest PPV [97%]. The combination of unilateral hydroureter and unilateral perinephric stranding had both the highest PPV [98%] and NPV [91%] compared with any individual sign alone. The tissue rim sign was present in [57%] of urteral stones and in none of the extraurinary calcifications. In patients having acute flank pain with suspected ureteral stone disease imaged with unenhanced CT, secondary signs including hydroureter, hydronephrosis, perinephric fat stranding, and renal parenchymal thickening are very common and provides supportive evidence that an acute obstructive process is present and that the urinary tract is likely responsible for the patients' complaints even when the ureteral stone itself could not be identified on CT

CT evaluation of liver hydatid disease

To elucidate distinctive CT imaging features that allow a diagnosis of hepatic hydatidosis. The computed tomographic [CT] findings of 58 patients with sonographically detected cystic liver lesions were prospectively analyzed. These patients were followed up until a final diagnosis was reached. By CT scanning we correctly localized and diagnosed 81 hepatic hydatid cysts in 50 patients. These were all proven by surgery or endoscopic retrograde cholangio-pancreatography [ERCP]. Stage III and II hydatid cysts were the commonest types [29% and 25% respectively]. 52% of the cysts were 5-10 cm at presentation. At CT, we identified some ancillary imaging features that help in the diagnosis of unilocular type I hepatic echinococcal cysts. Although no imaging feature can provide a definitive diagnosis of a unilocular type I hepatic echinococcal cyst, some ancillary imaging features may help in differentiating them from non parasitic simple liver cysts. Types II, III, and V hydatid cysts, on the other hand, have characteristic imaging features that allow their confidant diagnosis

Ultrasound evaluation of suspected appendicitis

To evaluate the sensitivity, specificity, accuracy, positive predictive value [PPV], and negative predictive value [NPV] of ultrasonographic and doppler US findings in the diagnosis of acute appendicitis. A total of 115 cases of clinically suspected appendicitis were prospectively examined by grey scale US and doppler US. Five patients were excluded from the study because of difficulty to perform the graded compression technique. In the other 115 patients who were included in the study population, US appendiceal and periappendiceal signs, as well as doppler US findings were evaluated. Definitive diagnosis was established at surgery and histopathological examination in 62 patients [59 patients with appendicitis and 3 patients with alternative final diagnosis], and at clinical follow up in 48 patients. The prevalence of appendicitis in this study was 54%. The appendix was identified in 80 [73%] of the 110 patients, which included 55 [93%] of 59 patients with appendicitis and 25 [49%] of 51 patients without appendicitis. The most accurate appendiceal finding for appendicitis was a diameter of >/= 6 mm and non compressibility, which both had an accuracy of 96%. The lack of visualization of the appendix had a NPV of 87%, while the visualization of a normal appendix with a diameter of < 6 mm had a NPV of 96%. Inflammatory periappendiceal fat changes had a sensitivity of 92%, PPV of 83%, and a NPV of 89%. Hyperaemia in the appendiceal wall, although having a low sensitivity [53%], it had both high specificity [92%] and high PPV [94%]. The other findings had both low PPV and NPV. A non compressible appendix with a threshold outer diameter of 6 mm under compression is the most accurate US finding for appendicitis; with high sensitivity, specificity, PPV, and NPV

Non enhanced helical ct scan in visualization of normal appendix

To evaluate the frequency of visualization, thickness, and anatomical features of the normal appendix at nonenhanced helical computed tomography [CT]. Two radiologists prospectively iterpreted, in consensus, the abdominal CT scans of 140 patients who were examined for renal colic assessment. They were blinded to patients' surgical history regarding a previous appendectomy. No contrast material was used. The frequency of visualization, and the two - wall thickness of normal appendix were recorded, as well as the anatomical features of the appendix and the effect of adequasy of intraperitoneal fat on identification of the appendix. The prevalence of appendectomy was 9% [13 of 140 patients]. The sensitivity, specificity, positive and negative predictive values, and accurasy of visualization of normal appendix were 77%, 85%, 98%, 27%, and 77% respectively. The frequency of visualization was lower in patients with less nintraperitoneal fat. The mean thickness of normal appendix if no intraluminal content was visualized was 6.6 mm +/- 1.0 mm, and the mean thickness excluding visualized intraluminal content was 3.6mm +/- 0.8 mm. Most normal appendices are seen at nonenhanced helical CT. The thickness of normal appendix, when the content is not recognizable, overlaps the values currently used to diagnose appendicitis at CT