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Spontaneous renal hemorrhage (SRH) is a diagnostic challenge and a significant cause of morbidity, and sometimes mortality. Early identification is essential to institute lifesaving and reno-protective interventions. In this review, we classify spontaneous renal hemorrhage by location, presentation and etiology. We also discuss the diagnostic approach to renal hemorrhage and optimum imaging modalities to arrive at the diagnosis. Finally, we review strategies to avoid missing a diagnosis of SRH and discuss the pitfalls of imaging in the presence of renal hemorrhage., (© 2024. The Author(s), under exclusive licence to American Society of Emergency Radiology (ASER).)

Abstract: Manganese-based contrast agents (MBCAs) show promise to complement gadolinium-based contrast agents (GBCAs) in magnetic resonance imaging (MRI) of the liver. Management of patients with focal liver lesions and severely impaired renal function uses unenhanced liver MRI or GBCA-enhanced MRI. However, unenhanced MRI risks reducing patient's survival.Gadolinium-based contrast agents, which help to detect and visualize liver lesions, are associated with increased risk of nephrogenic systemic fibrosis in renally impaired patients, a severe adverse event (AE) with potentially fatal outcome. Therefore, use of GBCA in patients with impaired renal function requires careful consideration. Other concerns are related to tissue deposition in the brain and other organs due to lack of gadolinium clearance, which could lead to concerns also for other patient populations, for example, those exposed to multiple procedures with GBCA. Of particular concern are the linear chelates that remain available for liver MRI, where there is no replacement technology. This has highlighted the urgency for safer alternatives.An alternative may be the drug candidate Ascelia-MBCA (ACE-MBCA, Orviglance), oral manganese chloride tetrahydrate. This candidate effectively visualizes and detects focal liver lesions, as demonstrated in 8 clinical studies on 201 adults (healthy or with known or suspected focal liver lesions). ACE-MBCA has a low and transient systemic exposure, which is likely the reason for its beneficial safety profile. The AEs were primarily mild and transient, and related to the gastrointestinal tract. This new, orally administered product may offer a simple imaging approach, allowing appropriate patient management in renally impaired patients when use of GBCA requires careful consideration.In this review, we highlight the clinical development of ACE-MBCA-a novel, liver-specific contrast agent. We begin with a brief overview of manganese properties, addressing the need for MBCAs and describing their optimal properties. We then review key findings on the novel agent and how this allows high-quality MRIs that are comparable to GBCA and superior to unenhanced MRI. Lastly, we provide our view of future perspectives that could advance the field of liver imaging, addressing the medical needs of patients with focal liver lesions and severe renal impairment.Our review suggests that ACE-MBCA is a promising, effective, and well-tolerated new tool in the radiologist's toolbox., Competing Interests: Conflicts of interest and sources of funding: T.B.B. and N.K. accepted paid consultancy from Bayer. H.P.H. and A.N. are employed at Ascelia Pharma. H.P.H. and A.N. also have shares in Ascelia Pharma. Ascelia Pharma funded editorial and writing services from Aixial Group. There were no other sources of funding or conflicts of interest., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

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., (Copyright © 2023. Published by Elsevier Ltd.)

Purpose of Review: Renal masses are a wide entity and a common finding in clinical practice. Detection of these masses has increased in the last years, yet mortality rates have slightly decreased., Recent Findings: According to the World Health Organization classification, there are 8 types, 51 subtypes, and a lot more subsequent subclassifications of renal tumors. Histopathological analysis should always be assessed for final diagnosis of theses tumors. However, imaging can be an important diagnostic guidance. The most common diagnoses of renal tumor are clear cell carcinoma, papillary renal cell carcinoma, angiomyolipoma, and transitional cell carcinoma. Nonetheless, a considerable variety of particular tumors can arise from the kidney, challenging the expertise of radiologists and urologists on this subject. The awareness of these unusual entities is vital for professionals working at a complex medical facility with greater volume of patients. We hereby present uncommon renal tumors and its pathological and radiological features.

Competing Interests: Dr Madrazo has no relevant conflicts of interest to disclose.

The liver has a complex vascular supply, which involves the inflow of oxygenated blood through the hepatic artery (systemic circulation) and deoxygenated blood through the portal vein (portal circulation), as well as the outflow of deoxygenated blood through the hepatic veins to the inferior vena cava. A spectrum of vascular variants can involve the liver. Some of these variants may result in areas of enhancement that can mimic more serious pathologic conditions. In this article, the authors discuss a spectrum of variants and pathologic conditions that may involve the liver vasculature. These include variants, anomalies, and diseases involving the portal vein, such as rudimentary portal vein, thrombosis, cavernous transformation, thrombotic angiitis, thrombophlebitis, transient hepatic attenuation difference or transient hepatic intensity difference, portal venous aneurysm, and portal vein gas. The hepatic artery can be involved by various diseases, including thrombosis, stenosis, and aneurysm or pseudoaneurysm. Unusual "third inflow" sources of venous inflow are also discussed, including aberrant right gastric vein, aberrant left gastric vein, epigastric-paraumbilical veins, and cholecystic vein. A spectrum of variants and diseases involving the inferior vena cava and hepatic veins, including thrombosis, Budd-Chiari syndrome, veno-occlusive disease, stenosis, torsion, congestive hepatopathy, and peliosis hepatis, are discussed. Vascular shunts are illustrated, including portosystemic shunts (intra- and extrahepatic), arterioportal shunt, shunts of hereditary hemorrhagic telangiectasia, and acquired arteriovenous fistula. Familiarity with the pathogenesis and imaging features of these vascular entities can aid radiologic diagnoses and guide appropriate patient management. © RSNA, 2017.

Background: Since March 2002, the United Network for Organ Sharing liver allocation policy has given extra priority to patients with hepatocellular carcinoma (HCC) who meet specific medical criteria. This study reviews our experience with liver transplantation for HCC under this system., Study Design: Between March 2002 and April 2009, 244 patients with HCC underwent primary liver or liver-kidney transplantation under the current allocation system at the University of Miami. Outcomes including HCC recurrence-free survival (RFS) and patient survival (PS) were assessed retrospectively. Clinical variables that predicted outcomes were analyzed., Results: The median time from listing to transplantation was 48 days. The median follow-up was 27.4 months, with an observed recurrence rate of 10.7%. The RFS rates at 1, 3, and 5 years after transplantation were 96.0%, 89.0%, and 83.6%, respectively. The PS rates at 1, 3, and 5 years after transplantation were 86.3%, 71.5%, and 61.7%, respectively. Among patients diagnosed with T2 HCC, a trend toward improved RFS was observed for those who received preoperative ablative therapy; PS was similar (p > 0.05). Outcomes (RFS and PS) for patients with T3 HCC were similar to those in patients with T2 HCC (p > 0.05). Patients with an alpha-fetoprotein >100 ng/mL had an RFS that was inferior to that in patients with an alpha-fetoprotein < or =100 ng/mL (p < 0.0001)., Conclusions: Under the current allocation system, transplantation for HCC results in excellent RFS; PS depends on factors other than HCC; the value of preoperative ablative therapy for patients with T2 HCC is uncertain; the current criteria could be expanded to include selected patients with T3 HCC; and an elevated AFP level is associated with an increased risk of HCC recurrence after transplantation., (Copyright 2010 American College of Surgeons. Published by Elsevier Inc. All rights reserved.)

Objective: The objective of this study was to report the sonographic abnormalities in a group of patients with angiographically proven innominate artery stenosis and occlusion., Materials and Methods: A review of all cerebrovascular sonograms at our institutions was undertaken to identify patients with complete or partial flow reversal in the right vertebral artery and reversal or midsystolic deceleration of flow in any one of the three major segments of the right carotid system (common, internal, or external carotid artery). The distribution and appearance of these abnormalities was evaluated, and the presence or absence of tardus-parvus waveforms was noted in any segment of the right carotid artery. Additionally, a left to right common carotid peak systolic velocity ratio (LCCA/RCCA) was calculated and compared to published normal values. All patients had correlative contrast or MR angiography. Correlation was made between the severity of stenosis as determined by angiographic images and waveform aberrations as well as the more objective LCCA/RCCA ratios., Results: Twelve patients were identified as having the abnormalities described above in the right vertebral and carotid arteries. Doppler waveforms from the right vertebral artery revealed that eight of the 12 patients had complete reversal of flow at rest. Bidirectional flow was found in the remaining four as manifested by the presence of marked midsystolic deceleration. In the carotid arteries, one patient had complete reversal of flow in all segments of the right carotid system. Waveforms with midsystolic deceleration were identified in at least one of the carotid arteries of the remaining 11 patients: common carotid artery (8/11 = 73%), internal carotid artery (10/11 = 91%), external carotid artery (3/11 = 27%). The average LCCA/RCCA was 3.1 with a range of 1.7 to 5.7 (normal = 0.7-1.3). All patients had severe innominate artery disease (from 70% to occlusion) by contrast angiography or MR angiography. There was no correlation between the angiographically determined degree of stenosis and the Doppler findings., Conclusion: A distinctive pattern of hemodynamic alterations occurs in the right vertebral and carotid arteries of patients with severe innominate artery disease. Findings include reversed or bidirectional flow in the right vertebral artery, the presence of midsystolic deceleration in any of the branches of the right carotid system, and elevated LCCA/RCCA ratio.

Continued improvements in graft survival have led to widespread acceptance of renal transplantation as the preferred treatment for the majority of patients with end-stage renal disease. The long-term care of these patients is often provided away from transplantation centers. This article presents both the clinical and imaging features of renal transplantation complications and their interventional management. Urologic and vascular complications may occur. Vascular complications include renal artery stenosis and renal artery and renal vein thrombosis. Ultrasound can accurately depict and characterize many of the potential complications of renal transplantation and increasingly magnetic resonance imaging also facilitates this role. In addition, interventional radiologic techniques allow nonsurgical treatment., ((c) RSNA, 2005.)

Purpose: To demonstrate the different patterns of renal infarction to avoid pitfalls. To present 'flip-flop enhancement' pattern in renal infarction., Materials and Methods: Retrospective review of a total of 41 renal infarction in 37 patients were done. These patients underwent initial CT and the diagnosis of renal infarction was confirmed with either follow up CT or at surgery., Results: Twenty-three patients had wedge-shaped focal infarcts, nine patients had global and five patients had multifocal infarcts of the kidneys. Cortical rim sign was seen predominantly with global infarcts. In five patients, a 'flip-flop enhancement' pattern was observed. In two patients, planned renal biopsies due to tumefactive renal lesions were cancelled because of 'flip-flop enhancement' pattern on follow up CTs., Conclusion: Although most of our cases were straightforward for the diagnosis of renal infarction, cases with tumefactive lesions and global infarctions without the well-known cortical rim sign were particularly challenging. We describe a new sign, flip-flop enhancement pattern, which we believe solidified the diagnosis of renal infarction in five of our cases. The authors recommend further investigations for association of flip-flop enhancement and renal infarction.

Objective: To examine the sonographic and angiographic imaging findings before and after uterine fibroid embolization for symptomatic leiomyoma., Methods: This prospective study involved 14 premenopausal women who underwent uterine fibroid embolization for symptomatic leiomyoma. Preprocedure sonography with color Doppler imaging was performed. Bilateral uterine artery embolization was successfully performed with the use of polyvinyl alcohol. Follow-up sonographic examinations were performed between 1 and 3 months after the procedure. The correlation between the sonographic appearance before and after embolization and the degree of decrease in uterine size was evaluated by using the Jonckheere-Terpstra 2-sided P test., Results: Preprocedure sonographic imaging showed a varied appearance to the fibroids. Color Doppler imaging primarily showed the fibroids to be vascular with marked peripheral blood flow. Postprocedure sonographic imaging showed decreased uterine size and echogenicity. Color Doppler imaging showed a marked decrease in the blood flow to the leiomyoma. There was no statistical significance in the relationship between echogenicity and vascularity shown before the procedure and the percent decrease in the size of the uterus., Conclusions: Although sonography is an efficient method for identifying leiomyomata and determining the reduction in size after uterine artery embolization, we were unable to identify any predictive characteristics of success for aiding the preprocedural assessment.

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.

Magnetic resonance cholangiopancreatography (MRCP) is an evolving new technique for noninvasive imaging of diseases of the biliary tree and pancreatic duct. The advantage of this method is that one can obtain maximum intensity projection (MIP) images of the pancreatico-biliary system similar to those obtained with endoscopic retrograde cholangiopancreatography (ERCP) without the need of administration of intravenous or oral contrast. Heavily T2-weighted sequences are used that render the bile and the intraductal pancreatic fluid bright against a dark background.

Abdominal hernias are a common clinical problem. The main types of abdominal hernias are external or abdominal wall hernias, which involve protrusion of abdominal contents through a defect in the abdominal wall; internal hernias, which involve protrusion of viscera through the peritoneum or mesentery and into a compartment in the abdominal cavity; and diaphragmatic hernias, which involve protrusion of abdominal contents into the chest. Clinical diagnosis of abdominal hernias can be difficult. However, plain radiography, radiography performed after administration of barium, and computed tomography allow evaluation of suspected abdominal hernias and detection of those that are clinically occult. The anatomic location of the hernia, the contents, and complications such as incarceration, bowel obstruction, volvulus, and strangulation can be demonstrated with radiologic examination. Occasionally, complications such as neoplasms or inflammatory conditions can be identified in the hernial contents. With abdominal imaging modalities, a variety of abdominal hernias can be confidently diagnosed.

Familiarity with the embryology of the lymphatic system is helpful in understanding the pathogenesis and radiologic appearance of lymphangiomas of the cervicothoracic region. By considering anatomic location and radiologic appearance, one can predict the type of lymphangioma present, the primordial lymph sac from which the malformation arose, and when it formed in embryonic life. Cystic hygromas are composed of large, dilated lymphatic spaces. They form when a primordial lymph sac fails to reestablish communication with the central venous system from which it arose. These lesions may also result from an aberrant bud arising from a primordial lymph sac. Cavernous and capillary lymphangiomas are composed of smaller lymphatic channels. They form from abnormally sequestered buds of the developing lymphatic mesenchyme responsible for the fine meshwork of terminal branches in the periphery of the embryo. Their growth may be inhibited by the relatively tougher tissues in the periphery (eg, skin and muscle) compared with the relatively loose fatty connective tissue in which cystic hygromas form. Not only can all types of lymphangioma occur in one lesion, but lymphatic and vascular malformations may also coexist.

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.

Endorectal sonography initially was developed for evaluation of the prostate and now has been adapted for evaluation of rectal and perirectal disease. We used endorectal sonography to evaluate a spectrum of diseases, including primary and recurrent rectal carcinoma, metastases, villous adenoma, leiomyosarcoma, endometriosis, sacrococcygeal teratoma, chordoma, retroperitoneal cystic hamartoma, pelvic lipomatosis, diverticulitis, and perirectal abscess. The technique has been useful in localization of perirectal abscesses and in sonographically guided biopsy of perirectal masses. Knowledge of normal sonographic anatomy of the rectum is essential in the evaluation of rectal and perirectal disease. In this essay, we describe the technique of endorectal sonography and illustrate the sonographic findings in a variety of diseases.

We have described 14 cases of large scrotal infections with diffuse involvement of testis and epididymis, thick septations within the cavity, and associated thickening of the scrotal wall and tunica albuginea. The combination of these findings should help distinguish this process from a diffuse neoplastic involvement of the testis where the scrotal wall is almost always of normal thickness. The presence of patchy inhomogenous testicular echo pattern should alert the sonologist to the presence of diffuse suppurative epididymo-orchitis, which may result in necrosis with subsequent orchiectomy in such patients.

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.

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.

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.

Twenty-nine patients had sonographic evaluation of the femoral triangle because of pain or swelling. The entities diagnosed by sonography were abscesses (seven), cellulitis (three), hematoma (five), nodal enlargement (four), aneurysm of the femoral artery (three), and thrombophlebitis of the femoral vein (seven). Both abscesses and hematomas were poorly defined primarily anechoic masses. Soft-tissue swelling but no distinct masses were present in cellulitis, and all cases of adenopathy were well defined anechoic masses. Aneurysms were also primarily well defined, pulsatile, anechoic masses except mycotic aneurysm, which may present as a primarily solid mass. The sonographic features of thrombophlebitis which has received scant attention in the sonographic literature are stressed. Findings suggest a dilated anechoic vein is characteristic of this entity. Although the sonographic findings or clinical data of many of these entities may be nonspecific, when used in combination, the correct diagnosis can usually be obtained.

A retrospective analysis of 84 ultrasound examinations (in 77 patients) was performed to assess the frequency of sonographic findings in chronic pancreatitis. The findings included: inhomogeneously increased echogenicity in 53% of these examinations, focal or diffuse enlargement in 41%, focal dense echoes in 40%, pseudocyst formation in 21%, and a hypoechoic head mass in 7%. Thirteen per cent of our patients had a normal sonogram. Several presentations of chronic pancreatitis not previously described in the sonographic literature included: pancreatic or common bile duct enlargement or pseudocyst formation with otherwise normal-appearing glands. There was no direct relationship between the presence of focal high-intensity echoes within the pancreatic parenchyma and the presence of radiographic calcification. There was no difference in the frequency of ultrasonic abnormalities between patients with and without clinical evidence of pancreatic insufficiency. These results indicate that the sonographic findings in chronic pancreatitis are significantly more varied than previous reports would indicate.

A retrospective study of 109 patients who underwent renal biopsy was designed to correlate the sonographic appearance of the kidney with the histologic changes and clinical and laboratory findings in various renal parenchymal diseases. The clinical, pathologic, and sonographic data were analyzed blindly and independently by a team from each corresponding discipline. There was no correlation between the specific sonographic appearance and the type of renal disease. There was a significant correlation between renal length and the prevalence of global sclerosis, focal tubular atrophy, and the number of hyaline casts per glomerulus. A significant positive correlation was also found between cortical echogenicity and the severity of global sclerosis, focal tubular atrophy, the number of hyaline casts per glomerulus, and focal leukocytic infiltration. While there was overall significant correlation between the degree of cortical echogenicity and blood urea nitrogen and creatinine concentrations in each group, a wide range of variance was present. It is not currently feasible to distinguish different types of renal medical disorders using diagnostic ultrasound.

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.

Autotransplantation of the kidney was performed in seven adult mongrel dogs. A model of acute tubular necrosis (ATN) was developed by subjecting the kidney to warm ischemia (37 degrees C) for 40 to 60 minutes. Serial ultrasound examinations were performed every 12 hours until the animal died or was killed. Sonographic findings were correlated with laboratory and histological data. Throughout the course of ATN, the characteristic normal echo pattern of the kidney remained unchanged in six of seven dogs. In one animal there were changes in the renal cortex, while the medullary pyramids showed no alteration from the base-line study. This contrasts with extensive abnormalities found during rejection.

We reviewed the CT of 20 patients with peripheral lung malignancies in which CT appearance suggested chest wall invasion on the basis of extension of mass around ribs into fat or muscle of the chest wall, or definite bone destruction. We correlated these findings with other radiographic studies and surgical and autopsy results. All 11 cases in which CT indicated chest wall involvement on the basis of definite bone destruction were confirmed. Tumor extension into the chest wall was disproven in six of the remaining nine cases in which invasion was suggested on the basis of tumor infiltration between ribs or extension of tumor into fat or soft tissue planes. Our findings confirm the lack of reliability of CT findings in determining the extension of malignancy into the chest wall, except when definite bone destruction is present.

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.

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.

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.