Ultrasound of pancreatic transplant complications: a primer for radiologists.

Pancreatic transplantation is an established treatment for patients with type 1 diabetes patients and select type 2 diabetes patients, with excellent survival rates as graft health is evaluated through regular imaging and early detection of complications. Amongst the various imaging methods that may aid in diagnosis of pancreatic transplant complications, ultrasound is a widely available, quick, portable, and cost-effective technique, often used as the sole method to assess for pancreatic transplant complications. When assessing a patient with a pancreatic transplant, the radiologist should be methodical in assessing the vasculature, the pancreatic parenchyma, and the peripancreatic regions. Complications can be categorised based on time from transplant and type of complications, and include vascular, parenchymal, and enteric/anastomotic complications. Doppler has a major role in the diagnosis of vascular complications including arterial and venous thrombosis, arterial stenosis, pseudoaneurysms, and haematomas. Pancreatic complications include rejections and pancreatitis, and are often diagnosed through a combination of clinical, laboratory, and imaging findings, such as pancreatic heterogeneity or the presence of pancreatic pseudocysts. Enteric/anastomotic complications include leaks and bowel obstructions, and may require cross-sectional imaging in addition to ultrasound. This review covers the most common and high-impact vascular, parenchymal, and enteric/anastomotic complications that should be considered in every radiologist's search pattern when assessing a pancreatic graft, as well as their respective postoperative timeframes.

Sonographic manifestations of acute renal vein thrombosis: an experimental study.

Complete unilateral ligation of the renal vein was done in five adult mongrel dogs. An initial ultrasound examination was performed at 6 hours with serial scans every 12 hours until the animals died or were sacrificed. There were a number of sonographic findings, consisting of immediate renal enlargement, increased cortical thickness, sparsely distributed cortical echoes with increased transonance, indistinct cortico-medullary boundary, parenchymal anechoic areas due to hemorrhage and hemorrhagic infarct, compressed renal parenchyma appearing as echogenic clusters, dilated renal veins, and renal rupture. These findings corresponded to changes in the pathologic specimens and were dependent upon the duration of the venous occlusion. In patients clinically suspected to have renal vein thrombosis, the combination of the above-described sonographic findings supplemented with findings on excretory urography should be sufficient for the diagnosis of renal vein thrombosis, eliminating the need for invasive procedures.

The value of radiographic and computed tomography in the staging of lung carcinoma.

A prospective double-blind study was undertaken to compare computed tomography (CT) and conventional radiographic tomography (RT) in the staging of lung carcinoma. Seventy-five patients had CT and RT of the mediastinum and hilum prior to operation. The presence or absence of metastasis to lymph nodes documented at the time of operation was the standard applied to the studies. CT correctly predicted the presence or absence of mediastinal lymphadenopathy in most cases (sensitivity 91%, specificity 94%), while RT was less helpful (sensitivity 61%, specificity 86%). Metastatic mediastinal lymph nodes in those patients with false negative CT and RT studies averaged only 0.8 cm in diameter, probably accounting for the negative radiographic findings. Both CT and RT had poor predictive values in detecting hilar lymphadenopathy (sensitivity 73% and 47%, specificity 87% and 72%, respectively). The predictive value of CT in the evaluation of mediastinal lymphadenopathy equaled that of mediastinoscopy or mediastinotomy. When CT of the mediastinum demonstrates no lymphadenopathy, invasive staging can be deferred for definitive thoracotomy. Since false positive values were seen with both CT and RT scans of the mediastinum (4% and 8%, respectively), invasive staging will still be necessary in those patients with positive studies.

Adult polycystic kidney disease: presymptomatic diagnosis for genetic counselling.

We evaluated 30 first degree relatives of 9 patients with end-stage renal disease secondary to adult polycystic kidney disease. The diagnostic accuracy of renal ultrasonography was compared with intravenous pyelogram with nephrotomography. In 27 patients the two tests were in agreement. In 3 patients both tests were abnormal but findings on IVP did not completely agree with ultrasonography. For early detection and genetic counselling, we recommend ultrasonography as the initial screening procedure for the evaluation of asymptomatic family members of a patient with APKD. IVP should only be considered if ultrasonogram is abnormal but not diagnostic of APKD.

Nonoperative management of blunt splenic injury in adults 55 years and older: a twenty-year experience.

The nonoperative management of splenic injury secondary to blunt trauma in older patients remains controversial. We have reviewed our experience from January 1978 to December 1997 with selective nonoperative management of blunt splenic injury in adults 55 years and older. Criteria for nonoperative management included hemodynamic stability with any transient hypotension corrected using less than 2,000 cm3 crystalloid infusion, a negative abdominal physical examination ruling out associated injuries, and a blood transfusion requirement of no more than 2 units attributable to the splenic injury. During the study period, 18 patients over age 55 with radiographic confirmation of a splenic injury met the above criteria for nonoperative management. Their mean age was 72 years (range 56-86), and 13 of the 18 were female (72%). The mean Injury Severity Score was 15 (range 4-29), with the mechanism of injury equally divided between automobile crashes (9) and falls (9). During a similar time period, 15 patients 55 years or older with splenic injury composed an operative group; these patients did not differ with respect to age (mean 68 years), sex (60% female), or mechanism of injury. CT scans of 8 patients managed nonoperatively were available and graded using the American Association for the Surgery of Trauma classification, with a mean score of 2.3 (range 2-3). Eight of the 18 nonsurgical patients received blood transfusions. None of the 18 patients who met the criteria for nonoperative management "failed" the protocol, and none were taken to the operating room for abdominal exploration. Two patients (11%) died of associated thoracic injuries after lengthy hospital stays, one at 10 days and one at 24 days. We conclude from our data that nonoperative management of blunt splenic injury in patients age 55 years and older is indicated provided they are hemodynamically stable, do not require significant blood transfusion, and have no other associated abdominal injuries.

Ultrasonic features of two cases of spinal cord hemangioblastoma.

Two patients with proven intramedullary spinal cord hemangioblastomas were examined with intraoperative ultrasound. The ultrasonic features of a hyperechoic intramedullary mass accompanied by nearby cysts and, in one case, by a syrinx correspond with well-known pathological and computed tomographic descriptions of these tumors. Ultrasonic guidance enabled the surgeon to identify the exact location of the tumors and to proceed with the surgery, limiting the dissection to the area detected. The ultrasound also revealed cysts associated with the tumors, thus providing valuable information to guide the progress of surgery.

Slice-thickness artifacts in gray-scale ultrasound.

We have become increasingly aware of the presence of a type of image artifact normally appearing in anechoic areas (eg, cyst, bladder, gallbladder) and giving the appearance of "sludge" or "debris." These artifactual echoes may be caused by the fact that the finite width of the transducer beam pattern produces a finite thickness of the patient scan plane. All echoes produced in this "thick" scan plane are misinterpreted as being due to structures in the normally assumed "thin" scan plane. We have tested and verified this hypothesis by simulating soft tissue interfaces with 400 grit silicon carbide sandpaper in a water tank. A set of clues are proposed to enable the rapid identification of these artifacts.

Color Doppler ultrasound of the genitourinary tract.

This paper discusses the role of color Doppler ultrasonography (CDU) as it applies to the genitourinary tract. CDU is beneficial in evaluating both the native and allograft kidney in the diagnosis of renal arterial and venous stenosis, arteriovenous fistulas, pseudoaneurysms, arterial and venous thrombosis, and in the characterization and staging of renal masses. CDU has redefined the role of ultrasonography in the evaluation of the scrotum as it relates to testicular torsion, inflammatory disorders and varicoceles. Early results of CDU in prostate carcinoma and benign prostate hypertrophy have shown limited success. Identifying and assessing the neurovascular bundle may have an impact on the staging of prostate carcinoma. It is hoped that the future addition of ultrasound contrast agents will further establish the role of color Doppler in the diagnosis of a variety of genitourinary diseases and disorders.

Computed tomographic features of esophageal intramural pseudodiverticulosis.

A patient with esophageal intramural pseudodiverticulosis (EIPD) was examined with computed tomography (CT). CT demonstrated marked thickening of the esophageal wall, diffuse irregularity of the esophageal lumen, and intramural gas collections--features typical of this entity. In the proper clinical setting, CT can confirm the diagnosis of EIPD, especially when other studies are equivocal. However, this case also demonstrates some of the limitations of CT in differentiating benign and malignant esophageal disorders.

Ultrasonic and computed tomographic features of mucocele of the appendix.

The ultrasonic features in three cases and computed tomographic (CT) findings in one case of mucocele of the appendix are presented. This entity appeared cystic on sonography and may have high-intensity echoes within it. The wall was not thickened and did not contain calcification, unlike previous descriptions. On CT, the mass was of soft tissue density, while previously, it had been described as cystic. Although mucocele of the appendix has a more variable appearance on sonography and CT than previously reported, a correct preoperative diagnosis can be made in most cases. Barium enema examination or calcification in the wall or in the mass itself may be necessary to distinguish this entity from lymphoma if the lesion is of soft tissue density on CT.

Sonographic features of parovarian cysts and their complications.

Parovarian cysts have received virtually no attention in the sonography literature, despite a common occurrence, constituting 10%-20% of adnexal tumorlike conditions in pathologic series. The sonographic features of 11 parovarian cysts, including a number with complications, are reported. Six uncomplicated lesions had the appearance of simple cysts found in other organs. One cyst had ruptured, and one lesion was associated with ipsilateral tubal torsion. Two cysts had echogenic areas representing blood clot. One cyst had a triangular papillation representing the development of a serous cystadenofibroma in its wall. This experience differs from previous reports in that there was increased incidence of preoperative recognition of an adnexal mass clinically, lack of identification of a fallopian tube exiting from the lateral aspect of the parovarian cyst and identification of complications sonographically, and the smaller average size of lesions, both clinically and sonographically. Parovarian cysts and their complications should be included in the differential diagnosis of cystic adnexal masses.

Ultrasonic findings in intramural exogastric lesions.

Four cases of intramural exogastric lesions studied by ultrasound are presented. In all four patients, a large mass was identified in the left mid- and upper abdomen with a strip of solid tissue extending toward the left hemidiaphragm anteriorly, adjacent to the left lobe of the liver. This finding, best demonstrated on longitudinal scanning, suggested that the mass originated in the stomach rather than in the spleen or splenic flexure of the colon, which are posterior in location. Two of the lesions were leiomyoblastomas and two leiomyosarcomas.

Clinical and imaging features of rhabdoid tumor of the kidney.

Rhabdoid tumor of the kidney (RTK) is a rare, highly malignant neoplasm of childhood. The clinical profile of this neoplasm differs from that of Wilms' tumor. We present two cases of RTK. In both our cases, large bulky masses with poorly defined margins and calcifications were demonstrated. The clinical and imaging findings are compared with other childhood renal neoplasms.

Postbiopsy renal transplant arteriovenous fistulas: color Doppler US characteristics.

Color Doppler ultrasound (US) with point-spectral analysis was performed on eight patients with postbiopsy renal transplant arteriovenous fistulas. Waveform analysis of the supplying artery documented decreased resistive indices in all cases and increased flow velocities in seven. The peak-systolic flow velocity in the arteries supplying the fistulas ranged from 55 to 180 cm/sec (mean, 92 cm/sec), while the range in normal arteries was 20-52 cm/sec (mean, 32 cm/sec). The resistive indices of the arteries supplying the fistulas ranged from 0.31 to 0.50 (mean, 0.45), while the resistive indices of the normal arteries ranged from 0.60 to 0.92 (mean, 0.74). Arterialization of the venous waveform from the draining vein was also documented in all cases. In six cases, the increased flow velocities resulted in increased color saturation toward white in the supplying artery (n = 2) or in both the artery and the draining vein (n = 4), which was detectable on the realtime image. In six cases, flow turbulence resulted in localized tissue vibration, which appeared as random color assignment in extravascular renal parenchyma adjacent to the fistula. Knowledge of these imaging and Doppler characteristics should aid in the identification of renal transplant arteriovenous fistulas with color Doppler US.

Ultrasonographic demonstration of undescended testes.

Twelve cryptorchid patients had sonographic evaluation of the inguinal region prior to surgical orchiopexy. When the testis was within the inguinal canal, the gonad was localized preoperatively by sonography in eight of nine patients. One patient had an associated inguinal hernia in which loops of bowel concealed the gonad. There were no false positive cases. The authors were not able to show abdominal or pelvic maldescended testes.

The role of ultrasound in the diagnosis of kidney allograft rejection.

Seventeen nephrectomized dogs underwent kidney transplantation from unrelated donors. Routine immunosuppressive therapy was administered. Serial ultrasound studies and biopsies and complete pathological examinations were performed and compared. A number of sonographic changes were observed within the renal parenchyma during rejection, some of which were present before a significant rise in serum creatinine levels. The medulla became enlarged due to edema, followed by growth of the rest of the kidney and thickening of the cortex. The cortical echoes became more sparsely distributed and either increased or decreased in amplitude; distribution was generalized or localized. During rejection, the corticomedullary boundary became indistinct. Later, a decrease in the renal sinus echoes was also noted. In 2 cases, perirenal fluid collections occurred as the result of renal rupture.

Inflammatory lesions of the groin: ultrasonic evaluation.

Sonograms of 72 patients with pain and swelling in the groin due to intravenous drug abuse were reviewed, together with 2 cases which were due to trauma. There were 27 abscesses, 36 cases of cellulitis or thrombophlebitis, 7 cases of lymphadenopathy, 3 hematomas, and 1 pseudoaneurysm. Most abscesses presented as distinct masses, while cellulitis was seen most often as soft-tissue swelling. However, 5 abscesses were manifested sonographically as diffuse soft-tissue swelling without a distinct mass, while 8 cases of cellulitis appeared as a mass. In most cases, ultrasound was able to distinguish diseases requiring surgery or percutaneous drainage from those that should respond to medical therapy. In some cases, percutaneous aspiration and/or follow-up sonograms after antibiotic therapy will be necessary for a specific diagnosis.

Computed tomographic findings in penetrating peptic ulcer.

Four cases of peptic ulcer penetrating the head of the pancreas were diagnosed by computed tomography (CT). Findings common to 3 cases included (a) an ulcer crater, (b) a sinus tract, and (c) enlargement of the head of the pancreas. Additional findings, not seen in all patients, included (d) edema involving the base of the ulcer and/or the adjacent bowel wall and (e) loss of fascial planes between the base of the ulcer and the head of the pancreas. Unlike other modalities, the inherent spatial resolution of CT allows a confident diagnosis of this important complication of peptic ulcer disease.

Sonographic findings in perforation of the gallbladder.

The sonographic findings in 13 patients with proven gallbladder perforation are described. Two patients were scanned immediately before and after gallbladder perforation. The sonographic findings before gallbladder perforation were gallbladder distension (one case) and gallbladder wall edema (one case). Pericholecystic collections develop after gallbladder perforation. These collections have a varied sonographic appearance ranging from anechoic to complex collections, and their internal characteristics seem to depend on the duration of the pericholecystic process. The residual gallbladder lumen or calculi can be identified within or peripheral to the pericholecystic process. The most acceptable mechanism for perforation of the gallbladder is: (1) impaction of a calculus in the cystic duct; (2) gallbladder distension due to secretion into its lumen by mucous glands located in the walls of the gallbladder; (3) vascular impairment of the gallbladder due to distension of the viscus; and (4) ischemia, necrosis, and perforation of the gallbladder wall. Gallbladder perforation is a significant complication of acute cholecystitis associated with morbidity and mortality. Detection of this complication of acute cholecystitis by clinical means is difficult since the patient's symptoms are similar to those of uncomplicated acute cholecystitis. The inherent resolution of sonography offers an excellent display of the gallbladder and surrounding tissues allowing detection of pericholecystic collection secondary to gallbladder perforation.