Fintan Regan

PLAIN ABDOMINAL X-RAY VERSUS COMPUTERIZED TOMOGRAPHY SCREENING: SENSITIVITY FOR STONE LOCALIZATION AFTER NONENHANCED SPIRAL COMPUTERIZED TOMOGRAPHY

PURPOSE Urolithiasis followup with plain abdominal x-ray requires adequate visualization of the calculus on the initial x-ray or computerized tomography (CT) study. We compared the sensitivity of plain abdominal x-ray versus CT for stone localization after positive nonenhanced spiral CT. MATERIALS AND METHODS We evaluated 46 consecutive nonenhanced spiral CT studies positive for upper urinary tract lithiasis for which concurrent plain abdominal x-rays were available. X-ray and CT studies were compared for the ability to visualize retrospectively a stone given its location by CT. A consensus of 1 radiologist and 3 urologists was reached in each case. Cross-sectional stone size and maximum length were measured on plain abdominal x-ray. RESULTS Plain abdominal x-ray and scout CT had 48% (22 of 46 cases) and 17% (8 of 46) sensitivity, respectively, for detecting the index stone (p <0.00004). Of the 39 stones overall visualized on plain abdominal x-ray only 19 (49%) were visualized on scout CT. Mean cross-sectional area and length of the stones on scout CT were 0.34 cm.2 (approximately 6 x 5.5 mm.) and 6. 5 mm., respectively, while the average size of those missed was 0.11 cm.2 (approximately 4 x 3 mm.) and 3.6 mm. The mean size differences in the groups were highly significant (p <0.0009). CONCLUSIONS Plain abdominal x-ray is more sensitive than scout CT for detecting radiopaque nephrolithiasis. Of the stones visible on plain abdominal x-ray 51% were not seen on CT. To facilitate outpatient clinic followup of patients with calculi plain abdominal x-ray should be performed when a stone is not clearly visible on scout CT.

Indium-111 capromab pendetide (ProstaScint) imaging to detect recurrent and metastatic prostate cancer

This study evaluated the utility of In-111 capromab pendetide imaging to detect prostate cancer metastases or local recurrence. The specific goal was to identify clinical factors such as prostate-specific antigen, pathologic stage, and Gleason score that were most predictive of a positive scan outcome. In addition, a new concept of a weighted Gleason score was defined and correlated with the scan outcome. Fifty-one patients with an elevated prostate-specific antigen level and otherwise negative workup were studied. Forty-eight patients had been treated by radical prostatectomy, two by radiation therapy, and one patient was studied before prostatectomy. Each patient received an intravenous injection of approximately 5 mCi of In-111 containing 0.5 mg of CYT 356, a conjugated site-specific monoclonal antibody against prostate specific membrane antigen. Tomographic blood pool images were obtained the day of injection. Four days later planar images and tomographic images of the abdomen and pelvis were obtained. Scans were interpreted by two experienced nuclear medicine physicians. Differences in the scan interpretation were settled by consensus. Scan outcomes were correlated with prostate-specific antigen levels, pathologic stage, Gleason score, weighted Gleason score, and clinical data. Of 51 scans, 70.6% (36 of 51) were positive. Eight patients had abnormal activity in the prostatic fossa, 12 patients had abnormal activity in the abdominal or pelvic lymph nodes, and 16 patients demonstrated abnormal activity in both areas. One patient with a positive scan underwent lymphadenectomy and was confirmed to be a true positive. Patients with a prostate-specific antigen level greater than 10 ng/ml, a weighted Gleason score higher than 4.5, or prostate-specific antigen levels greater than 2 ng/ml plus a weighted score higher than 4.5 showed positive rates of 100% (6 of 6), 88.2% (14 of 16), and 100% (6 of 6), respectively. In-111 capromab pendetide imaging was useful to detect metastases or local recurrence. Serum prostate-specific antigen levels and weighted Gleason scores are good predictive factors of the likelihood of a positive scan outcome.

The diagnostic utility of HASTE MRI in the evaluation of acute cholecystitis

PURPOSE The purpose of this study was twofold: (a) to determine the significance of high signal intensity surrounding the gallbladder as seen on T2-weighted HASTE (half-Fourier acquisition single shot turbo SE) MR images in patients with acute cholecystitis and (b) to determine the sensitivity of T2-weighted HASTE MR images in detecting gallbladder and common bile duct (CBD) calculi in patients with acute cholecystitis. METHOD Seventy-two patients with a suspicion of acute cholecystitis were referred for HASTE MRI over a 2 year period. Forty-one patients underwent MRI after sonography and the remaining 31 patients before sonography. MR images were independently evaluated for the presence of MR pericholecystic high signal and gallbladder and CBD calculi. Findings were correlated with results obtained at sonography and at surgery. RESULTS Of the 72 patients imaged with HASTE MRI, 55 had cholecystitis based on clinical, sonographic, and/or surgical findings. Of these, 45 had acute and 10 had chronic cholecystitis. HASTE MRI demonstrated MR pericholecystic high signal in 41 of 45 (91%) of the patients with acute cholecystitis. The sensitivity of HASTE MRI in diagnosing acute cholecystitis was 91%. The specificity was 79%. The positive predictive value was 87%, the negative predictive value was 85%, and the overall accuracy of the test was 89%. Gallbladder stones were seen by HASTE MRI in 38 of 41 (93%) of patients with acute calculus cholecystitis demonstrated at sonography. CBD stones were demonstrated by HASTE MRI in seven of nine (78%) patients and by sonography in five of nine (56%) patients with documented choledocholithiasis on conventional cholangiography. CONCLUSION HASTE MRI has a high degree of accuracy in diagnosing acute cholecystitis based on the single finding of pericholecystic MR high signal. A similar level of accuracy is demonstrated in detecting gallbladder stones. Biliary duct calculi are detected with even greater accuracy than with sonography in patients with acute cholecystitis. Invasive preoperative endoscopic retrograde cholangiography may therefore be limited to only those patients with acute cholecystitis and CBD stones demonstrated on HASTE MRI. These features make HASTE MRI and ideal imaging modality in the initial evaluation of acute biliary pain and may ultimately replace sonography in the preoperative evaluation of acute cholecystitis.

MR cholangiography in biliary obstruction using Half-Fourier acquisition

PURPOSE Our goal was to evaluate biliary obstruction using a T2-weighted, turbo, SE MR sequence with half-Fourier acquisition (HASTE). METHOD A prospective evaluation of 21 consecutive patients with clinical evidence of obstructive jaundice was carried out comparing HASTE MR cholangiography (MRC) to endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography. A control group of five normal volunteers was also evaluated. The study group was imaged with a 1.5 T MR scanner using a body coil. The HASTE sequence was applied in axial, coronal, and oblique sagittal planes. Ultrafast acquisition scanning times allowed the use of a single breath hold. Bile duct dilatation, level of obstruction, and cause of obstruction were assessed on both imaging modalities by two radiologists blinded to the clinical diagnosis and to each others results. RESULTS All studies were interpretable with anatomy well seen in 82% of the cases. MRCs of a normal control group were correctly interpreted. The presence of biliary dilatation was accurately depicted by HASTE MRC in 100% of patients with complete interobserver agreement. The level of obstruction was depicted correctly in 87% of patients with 93% interobserver agreement. The right main duct was seen by MRC in 80% of obstructed systems. The left main duct was seen in all obstructed patients. The gallbladder was identified in 88% of patients by MRC. Common bile duct stricture and stones could be differentiated as a cause of obstruction in all cases. CONCLUSION MRC using the HASTE imaging sequence can safely and accurately depict the presence and level of biliary obstruction. The fast acquisition time of 13 s/scan makes the technique suitable for uncooperative and ill patients. HASTE MRC should be considered an alternative procedure to direct cholangiography in selected patients.

The role of computerized tomography in the evaluation of complications after laparoscopic urological surgery.

PURPOSE Radiographic evaluation may be necessary to assess the possible complications of laparoscopic procedures. We undertook a retrospective review to determine the indications for and findings of computerized tomography (CT) in symptomatic patients after urologic laparoscopic surgery. MATERIALS AND METHODS Of 400 laparoscopic urological procedures performed between July 1993 and September 1996, 20 patients (5%) had postoperative symptomatology that could not be explained by physical exam or routine clinical studies. An abdominal CT scan was obtained (1 to 120 days after the procedure) to help determine a diagnosis. CT findings were correlated with the indication for the study and clinical followup. RESULTS The indications for CT were unexplained pain, fever, leukocytosis or falling hematocrit. Thirteen patients had significant findings related to their surgery that were identified by CT. In 2 cases, we identified pathology unrelated to the surgery. Therefore, CT identified a symptom-related diagnosis in 75% of patients (15 of 20). Each scan for decreasing hematocrit demonstrated a hematoma. In all patients with unexplained fever or leukocytosis, CT revealed the cause. CT evaluation of atypical postoperative pain demonstrated a pathological cause in 58% (7 of 12). Percutaneous or laparoscopic surgical intervention was required in 4 of 20 patients. In 8 patients scanned by postoperative day 6, intraperitoneal or retroperitoneal gas was identified in 3 who had an abdominal incision made for intact specimen removal and in 1 with a perforated ulcer. CONCLUSIONS CT after urologic laparoscopy is indicated in patients with significant clinical findings in whom routine examination and tests are not diagnostic. CT can reliably identify postoperative bleeding, urinary leak or obstruction and can also detect nonurinary pathology.

Ventilation-perfusion scintigraphic evaluation of pulmonary clot burden after percutaneous thrombolysis of clotted hemodialysis access grafts

The objective of this study is to determine, by using rigorous methods, if pulmonary perfusion defects were detectable by ventilation-perfusion scintigraphy after percutaneous thrombolysis of clotted hemodialysis access grafts. Thirteen patients were studied. Four patients underwent pharmacomechanical thrombolysis with urokinase and the remainder had mechanical thrombolysis alone. Pre- and postthrombolysis scintigraphic studies were performed on all patients. Perfusion defects were described as vascular (well-defined borders confined to segmental boundaries) or nonvascular. Vascular defects were graded by severity (0 to 3) and area (0 to 3) for each involved segment. Nonvascular defects were graded by severity (0 to 1) and area (0 to 1). Two experienced readers evaluated the scans blinded to each others results and all other clinical data, including thrombolysis outcomes. Twelve patients did not have any significant worsening of their perfusion defect scores postthrombolysis. In only one patient did a study show a new nonvascular perfusion defect with a matching ventilation abnormality. The defect was believed to be caused by mucus plugging. The patient had no evidence of pulmonary embolism. Our study suggests emboli that resulted from the pharmacomechanical or mechanical thrombolysis procedure were either small, underwent lysis before impacting the lung, or were below the limit of detection of ventilation-perfusion scintigraphy.

MRI of bowel obstruction using the HASTE sequence.

High quality MR images of the gastrointestinal tract are now obtainable using a T2-weighted fast SE MR sequence with half-Fourier acquisition of data (the HASTE sequence). This fast sequence can acquire a set of images in a single breath hold and is insensitive to peristalsis-related artifact. It can be used with other imaging modalities in defining bowel obstruction and is accurate in determining the presence of bowel dilation and level of obstruction and in differentiating obstructing tumor from other causes of obstruction.

Functional MRI for the assessment of gastric motility--a better test?

Kunz P, Crelier GR, Schwitzer W, et al. Gastric Emptying and Motility: Assessment With MR Imaging–Preliminary Observations Radiology 1998;207:33–40

Tc-99m MDP scintigraphy of temporal bone metastasis from breast carcinoma

The authors present a case of breast carcinoma metastasis to the petrous apex demonstrated by Tc-99m MDP bone scintigraphy. Metastasis to the temporal bone is rare and difficult to detect due to its delayed symptomatology and occurrence at the advanced stage of the disease. Knowledge of the principal neoplasms susceptible to spread to the temporal bone, their different routes of propagation, and respective sites of temporal bone involvement is helpful in the work-up strategy for metastases.

Functional MRI for the Assessment of Gastric Motility|[mdash]|A Better Test|[quest]|

Kunz P, Crelier GR, Schwitzer W, et al. Gastric Emptying and Motility: Assessment With MR Imaging–Preliminary Observations Radiology 1998;207:33–40