CT evaluation of renovascular disease

Diffusely Increased FDG Uptake of the Kidney Caused by Severe Renal Artery Stenosis

ABSTRACT

Renal artery stenosis can result in renovascular hypertension and ischemic nephropathy. We describe FDG PET/CT and delayed abdominal FDG PET/MRI findings in a kidney associated with severe renal artery stenosis resulting from renal artery invasion in retroperitoneal alveolar echinococcosis. The renal parenchyma showed diffusely increased activity on both FDG PET/CT and delayed FDG PET/MRI. There was no activity in the renal collecting system on FDG PET/CT and focal urine activity in the renal calyces on delayed FDG PET/MRI. This case indicates that renal artery stenosis should be included in the differential diagnosis of diffuse renal parenchymal FDG uptake.

Skull Base Repair following Resection of Vestibular Schwannoma: A Systematic Review (Part 2: The Translabyrinthine Approach)

Objectives  Despite advances in skull base reconstruction techniques, cerebrospinal fluid (CSF) leaks remain a relatively common complication after translabyrinthine (TL) vestibular schwannoma (VS) surgery. We conducted a systematic review to synthesize the repair techniques and materials used in TL VS surgery to prevent CSF leaks. Design  A systematic review of studies published since 2000 reporting techniques to prevent CSF leaks during adult TL VS surgery was conducted. A narrative synthesis of primary repair protocols was produced, and a taxonomy was established. Additionally, the advantages, disadvantages, and associated CSF leak rates of different repair protocols were extracted. Results  All 43 studies were case series, and 39 were retrospective. Repair strategies included heterogeneous combinations of autografts, xenografts, and synthetic materials. A taxonomy was produced, classifying repairs into seven distinct stages, including approaches to the dura, middle ear cleft, air cells, TL bony defect, extra-cranial soft tissue, postoperative dressings, and CSF diversion. The median postoperative incidence of CSF leaks was 6% (interquartile range: 0-10%). Conclusions  This systematic review reveals substantial inter-institutional heterogeneity in intraoperative strategies to prevent CSF leaks following TL VS surgery. However, comparing these techniques is challenging due to the multiple predictive factors for CSF leaks and their inconsistent reporting. We propose a taxonomy of seven stages to classify operative techniques and materials aimed at preventing CSF leaks. We recommend that future evaluations should adopt a prospective approach encompassing data collection strategies that considers all operative stages described by our taxonomy.

Acute renal infarction mimicking renal colic: A case report and review of the literature

Renal infarction is a rare pathology, which can be life-threatening for the kidney. Its low incidence and non-specific clinical manifestations make it difficult to diagnose, often resulting in delayed or misdiagnosis. Contrast-enhanced CT has a role to play in early positive diagnosis, enabling rapid and effective management. We report the case of a right renal infarction simulating renal colic, with a review of the literature.

Traumatic Renal Artery Occlusion in Children: A Case Report

Blunt trauma is a major cause of death in children, with renal arterial injuries occurring in less than 1% of cases. Traumatic renal artery occlusion (RAO) in children is rare and results in the loss of ipsilateral renal perfusion. Clinical signs are often nonspecific, and there is a lack of information on the exact incidence and management outcomes of these rare cases in children. We report a case of unilateral RAO in a 13-year-old boy with polytrauma. He was diagnosed with right RAO and hepatic laceration after a fall. A conservative approach yielded favorable outcomes despite the loss of function in the right kidney. In stable polytrauma patients, prompt diagnosis of RAO is crucial for treatment optimization and potential kidney salvage.

Computed Tomography in Infectious Endocarditis

Imaging is one of the cornerstones in diagnosis and management of infective endocarditis, underlined by recent guidelines. Echocardiography is the first-line imaging technique, however, computed tomography (CT) has a class I recommendation in native and prosthetic valve endocarditis to detect valvular lesions in case of possible endocarditis and to detect paravalvular and periprosthetic complications in case of inconclusive echocardiography. Echocardiography has a higher diagnostic accuracy than CT in detecting valvular lesions, but not for diagnosing paravalvular lesions where CT is superior. Additionally, CT is useful and recommended by guidelines to detect extracardiac manifestations of endocarditis and in planning surgical treatment including assessment of the coronary arteries. The advent of photon-counting CT and its improved spatial resolution and spectral imaging is expected to expand the role of CT in the diagnosis of infective endocarditis. In this review, we provide an overview of the current role of CT in infective endocarditis focusing on image acquisition, image reconstruction, interpretation, and diagnostic accuracy.

Renal Infarction as the First Manifestation of Undiagnosed Atrial Fibrillation With Coexisting Left Atrial Thrombus: A Case Report and Review of the Literature

Acute renal infarction, presenting with nonspecific symptoms, such as abdominal pain, nausea, vomiting, and hematuria, can lead to delayed diagnosis due to similarities with other medical conditions. Computed tomography with IV contrast is used to diagnose renal parenchymal infarction, treated through surgical, percutaneous interventions, and anticoagulation therapy. Investigation for the infarction source is crucial, particularly in the absence of prior cardiac issues, necessitating heart rhythm monitoring and an echocardiogram to evaluate paroxysmal atrial fibrillation (PAF) and intracardiac thrombus, respectively. Renal infarction may elevate blood pressure due to renin release, recommending medications like angiotensin-converting enzyme inhibitors/angiotensin receptor blockers. We present a case of renal infarction due to PAF with a concomitant intracardiac thrombus.

Prolonged hiccups induced by renal infarction: a case report

BACKGROUND

Hiccups are common symptoms that last for less than 48 hours. However, we encountered a case of renal infarction in a patient with prolonged hiccup. The relationship between hiccups and renal infarction is important in differentiating patients with prolonged hiccups.

CASE PRESENTATION

An 87-year-old Japanese man with atrial fibrillation and receiving antithrombotic therapy presented to the emergency department with prolonged hiccups. The patient discontinued antithrombotic therapy for atrial fibrillation due to subcortical bleeding, after which he experienced right back pain. He was diagnosed with right renal infarction based on computed tomography images, and the antithrombotic therapy was continued. The patient's hiccups ceased, and he was discharged on hospital day 11.

CONCLUSION

Hiccups can be induced by various clinical conditions. It is hypothesized that the inflammation of the right kidney infarction stimulated the diaphragm and induced prolonged hiccups in this patient; this theory is supported by the computed tomography images. This case report shows that internal organ diseases irritating the diaphragm can cause hiccups, and renal disease should be considered in patients with prolonged hiccups.

Spontaneous Suburothelial Hemorrhage: The Crucial Role of Radiology in Preventing Unnecessary Interventions

Spontaneous suburothelial hemorrhage (SSH), also known as Antopol Goldman lesion, is a rare condition characterized by spontaneous bleeding into the renal sinus and proximal ureter wall. This case report describes the clinical presentation, imaging findings, and management of SSH in a 20-year-old female initially suspected to have urothelial malignancy. Imaging features of SSH include pre-contrast hyperdensity and non-enhancing thickening of the pelviureteric wall, which can mimic transitional cell carcinoma (TCC) and lead to unnecessary interventions. Radiologists should maintain a high level of suspicion for SSH and be aware of its imaging characteristics to avoid misdiagnosis. Additionally, clinical data, such as bleeding dyscrasia, can aid in the imaging diagnosis. This report provides insights into the diagnosis and management of SSH while offering a comprehensive literature review on its clinical presentation and imaging features. Increased awareness of SSH will facilitate accurate diagnosis and appropriate management, avoiding unnecessary interventions for patients with this benign condition.

Wunderlich Syndrome: Comprehensive Review of Diagnosis and Management

Wunderlich syndrome (WS), which was named after Carl Wunderlich, is a rare clinical syndrome characterized by an acute onset of spontaneous renal hemorrhage into the subcapsular, perirenal, and/or pararenal spaces, without a history of antecedent trauma. Patients may present with a multitude of symptoms ranging from nonspecific flank or abdominal pain to serious manifestations such as hypovolemic shock. The classic symptom complex of flank pain, a flank mass, and hypovolemic shock referred to as the Lenk triad is seen in a small subset of patients. Renal neoplasms such as angiomyolipomas and clear cell renal cell carcinomas that display an increased proclivity for hemorrhage and rupture contribute to approximately 60%-65% of all cases of WS. A plethora of renal vascular diseases (aneurysms or pseudoaneurysms, arteriovenous malformations or fistulae, renal vein thrombosis, and vasculitis syndromes) account for 20%-30% of cases of WS. Rare causes of WS include renal infections, cystic diseases, calculi, kidney failure, and coagulation disorders. Cross-sectional imaging modalities, particularly multiphasic CT or MRI, are integral to the detection, localization, and characterization of the underlying causes and facilitate optimal management. However, large-volume hemorrhage at patient presentation may obscure underlying causes, particularly neoplasms. If the initial CT or MRI examination shows no contributary causes, a dedicated CT or MRI follow-up study may be warranted to establish the cause of WS. Renal arterial embolization is a useful, minimally invasive, therapeutic option in patients who present with acute or life-threatening hemorrhage and can help avoid emergency radical surgery. Accurate diagnosis of the underlying cause of WS is critical for optimal patient treatment in emergency and nonemergency clinical settings. ^©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Multimodal imaging approach in hyponatremic hypertensive syndrome. A rare case of pediatric unilateral hypoplasia of the main renal artery combined itself with stenosis and review of literature

Renal artery stenosis (RAS) accounts for approximately 5%-10% of secondary renovascular hypertension in the pediatric population. It can occur as an isolated entity, or as a hypoplasia combined itself with stenosis. Hypoplasia, or long-segment developmental narrowing, is a rare cause of renovascular hypertension. Hyponatremic hypertensive syndrome (HHS) is a malignant complication of unilateral RAS and/or renal artery hypoplasia. Hyponatremia, hypokalemic hypochloremic metabolic alkalosis, nephrotic range proteinuria, polyuria, polydipsia, and weight loss are the most common findings. In particular, hypertension remains refractory despite aggressive antihypertensive therapy. Laboratory findings of elevated plasma levels of renin in most case suggest that the stimulation of renin release from the ischemic kidney plays an important pathophysiologic role. HHS is a diagnostic and therapeutic challenge in children. We report a case of a unilateral right renal artery hypoplasia, complicated by a segmental narrowing, in a 17-month-old male, clinically symptomatic for hypertension. We emphasize the role of ultrasound, computed tomography, and digital subtraction angiography that should be planned as reliable and non-invasive multimodal imaging approach.

Spontaneus Suburothelial Hemorrhage Associated With Forniceal Rupture and Retroperitoneal Hemorrhage

Spontaneous suburothelial hemorrhage is a rare process of unclear pathologic etiology, although it has been associated with bleeding diathesis and anticoagulation. The most common clinical presentation is acute onset flank pain and macroscopic hematuria. On imaging, there is a mural thickening of the renal pelvis and upper ureters leading to luminal narrowing. Despite luminal narrowing, hydronephrosis has only rarely been reported in the association. The imaging finding of mural thickening has led to the misdiagnosis as malignancy, resulting in unnecessary nephrectomy. Suburothelial hemorrhage can be unilateral or bilateral, although the majority of reported cases are unilateral. We present a case of a patient with bilateral spontaneous suburothelial hemorrhage with forniceal rupture and spontaneous retroperitoneal hemorrhage, a unique triad compared to prior cases presented in the literature.

Renovascular involvement of systemic vascular disease: a pictorial review

Like many solid organs, the kidneys are susceptible to a wide variety of systemic vascular diseases. Comprising a significant subset of these diseases are the vasculitides, broadly encompassing numerous inflammatory conditions of the blood vessels. However, many of these conditions are non-vasculitic and non-inflammatory, and differentiation of these entities is crucial to guide the initiation of proper therapy. These non-vasculitic diseases include coagulopathic conditions leading to vascular complications, hemolysis, and hematogenous processes that can affect multiple organ systems. These systemic diseases can result in both macrovascular and microvascular pathology, involving the arteries, veins, and smaller vessels, and management of these conditions can differ significantly depending upon the underlying pathophysiology. Because the clinical manifestations of these disease processes can be heterogeneous, ranging from renal dysfunction to life-threatening hemorrhage, proper recognition of these entities is essential to help guide clinicians to the correct diagnosis and prevent potentially disastrous complications. Many of these systemic vascular processes can be detected by non-invasive imaging, including computed tomography (CT) and magnetic resonance imaging (MRI), and identification of their characteristic renal manifestations by radiologists is a critical component of patient care. This review covers a variety of these diseases and their imaging manifestations, to aid in their recognition and better equip radiologists to provide vital diagnostic information that can optimize patient care.

Multimodality imaging review of focal renal lesions

Background

Focal lesions of the kidney comprise a spectrum of entities that can be broadly classified as malignant tumors, benign tumors, and non-neoplastic lesions. Malignant tumors include renal cell carcinoma subtypes, urothelial carcinoma, lymphoma, post-transplant lymphoproliferative disease, metastases to the kidney, and rare malignant lesions. Benign tumors include angiomyolipoma (fat-rich and fat-poor) and oncocytoma. Non-neoplastic lesions include infective, inflammatory, and vascular entities. Anatomical variants can also mimic focal masses.

Main body of the abstract

A range of imaging modalities are available to facilitate characterization; ultrasound (US), contrast-enhanced ultrasound (CEUS), computed tomography (CT), magnetic resonance (MR) imaging, and positron emission tomography (PET), each with their own strengths and limitations. Renal lesions are being detected with increasing frequency due to escalating imaging volumes. Accurate diagnosis is central to guiding clinical management and determining prognosis. Certain lesions require intervention, whereas others may be managed conservatively or deemed clinically insignificant. Challenging cases often benefit from a multimodality imaging approach combining the morphology, enhancement and metabolic features.

Short conclusion

Knowledge of the relevant clinical details and key imaging features is crucial for accurate characterization and differentiation of renal lesions.

Simultaneous renal infarction and splenic infarction as a possible initial manifestation of COVID-19: A case report

We recommend testing for SARS-CoV-2 in a patient with an unexplained thromboembolic event, even in the absence of fever or respiratory symptoms.

Bilateral acute renal cortical necrosis after a dog bite: case report

Background

Capnocytophaga canimorsus is a Gram-negative capnophilic rod and part of dogs/cats’ normal oral flora. It can be transmitted by bites, scratches, or even by contact of saliva with injured skin. Asplenic patients and patients with alcohol abuse are at particular risk for fulminant C. canimorsus sepsis. However, also immunocompetent patients can have a severe or even fatal infection. This is the first case of a severe C. canimorsus infection in an immunocompromised host complicated by acute renal cortical necrosis with a “reverse rim sign” in contrast-enhanced computed tomography on hospital admission.

Case presentation

We report the case of a 44-year functionally asplenic patient after an allogeneic stem cell transplantation, who presented with septic shock after a minor dog bite injury 4 days prior. Because of abdominal complaints, epigastric pain with local peritonism, and radiological gallbladder wall thickening, an abdominal focus was suspected after the initial work-up. The patient underwent emergent open cholecystectomy, but the clinical suspicion of abdominal infection was not confirmed. Septic shock was further complicated by cardiomyopathy and disseminated intravascular coagulation. As a causative pathogen, C. canimorsus could be isolated. The clinical course was complicated by permanent hemodialysis and extensive acral necrosis requiring amputation of several fingers and both thighs.

Conclusion

We present a severe case of a C. canimorsus infection in a functionally asplenic patient after a minor dog bite. The clinical course was complicated by septic shock, disseminated intravascular coagulation, and the need for multiple amputations. In addition, the rare form of acute renal failure - bilateral acute renal cortical necrosis – was visible as “reverse rim sign” on computed tomography scan. This case is an example of the potential disastrous consequences when omitting pre-emptive antibiotic therapy in wounds inflicted by cats and dogs, particularly in asplenic patients.

Systemic arterio-venous thrombosis in COVID-19: A pictorial review

Coronavirus disease 2019 (COVID-19) is caused by the novel coronavirus severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Systemic complications include cardiovascular, neurological, hepatic, renal and altered coagulation. Derangements in haemostasis with SARS-CoV-2 infection have been termed COVID-19 associated coagulopathy (CAC). CAC is postulated to be one of the significant causes for sudden deaths in this pandemic, with infection of endothelial cells and subsequent endotheliitis through angiotensin-converting enzyme-2 receptors playing a key role in the pathogenesis. In this pictorial review, we describe the imaging findings in a multitude of extrapulmonary arterial (aorta, cerebral, mesenteric, renal and peripheral arterial system) and venous thrombotic phenomena detected on contrast-enhanced computed tomography and magnetic resonance imaging of COVID-19 patients which could not be attributed to any other causes. Knowledge of incidence of these complications, lowering the threshold for diagnostic imaging in symptomatic patients and timely radiological detection can play a vital role in subsequent management of these critically ill patients.

Infiltrative Renal Malignancies: Imaging Features, Prognostic Implications, and Mimics

Infiltrative renal malignancies are a subset of renal masses that are morphologically characterized by a poorly defined interface with the renal parenchyma. Infiltrative renal malignancies are less common but more aggressive than more typical renal malignancies and carry an overall worse prognosis. Although an infiltrative renal process often represents a malignant neoplasm, infiltrative masses include a wide spectrum of diseases including primary renal cortical, medullary, and pelvic tumors; lymphoproliferative processes; metastases; and various infectious, inflammatory, immune-mediated, and vascular mimics. The imaging features of these masses are often nonspecific, but with the appropriate history, laboratory results, and clinical context, the radiologist can help narrow the diagnosis and guide further treatment. An invited commentary by Lee is available online.Online supplemental material is available for this article. ^©RSNA, 2021.

Wunderlich Syndrome: Wonder What It Is

Wunderlich syndrome (WS) refers to spontaneous renal or perinephric hemorrhage occurring in the absence of known trauma. WS is much less common than hemorrhage occurring after iatrogenic or traumatic conditions. Lenk's triad of acute onset flank pain, flank mass, and hypovolemic shock is a classic presentation of WS but seen in less than a quarter of patients. The majority of patients present only with isolated flank pain and often imaged with an unenhanced CT in the emergency department. The underlying etiology is varied with most cases attributed to neoplasms, vascular disease, cystic renal disease and anticoagulation induced; the etiology is often occult on the initial exam and further evaluation is necessary. Urologists are familiar with this unique entity but radiologists, who are more likely to be the first to diagnose WS, may not be familiar with the imaging work up and management options. In the last decade or so, there has been a conspicuous shift in the approach to WS and thus it will be worthwhile to revisit WS in detail. In our review, we will review the multimodality imaging approach to WS, describe optimal follow up and elaborate on management.

Role of imaging in visceral vascular emergencies

Differential diagnosis in non-traumatic acute abdomen is broad and unrelated diseases may simulate each other from a clinical perspective. Despite the fact that they are not as common, acute abdominal pain due to diseases related to visceral vessels may be life-threating if not detected and treated promptly. Thrombosis, dissection, and aneurysm in the abdominal visceral arteries or thrombosis in visceral veins may cause acute abdominal pain. Imaging with appropriate protocoling plays a fundamental role in both early diagnosis and determination of the treatment approach in these cases where early treatment can be life-saving. Computed tomography (CT) appears to be the most effective modality for the diagnosis as it provides high detail images in a very short time. Patient cooperation is also a less concern as compared to magnetic resonance imaging (MRI). As the imaging findings may sometimes be really subtle, diagnosis may be difficult especially to inexperienced imagers. Correct protocoling is also very critical to detect arterial abnormalities as visceral arterial abnormalities may not be detectable in portal phase only abdominal CT scans. In this article, we aimed to increase awareness among imaging specialists to these not very common causes of acute abdomen.

Does the stapler for en bloc resection of renal pedicles during kidney removal surgery increase the risk of arteriovenous fistula?

BACKGROUND

It was previously thought that renal hilum en bloc ligation during kidney removal may increase the risk of renal arteriovenous fistula (AVF) formation. We evaluated the safety and effectiveness of en bloc ligation of the renal pedicle using a stapler during laparoscopic nephrectomy and nephroureterectomy.

METHODS

Ninety patients underwent en bloc renal hilar ligation using 45-mm endo-gastrointestinal anastomosis stapler and 2.5-mm staples during laparoscopic nephrectomy and nephroureterectomy from 2002 to 2015. Perioperative outcomes including estimated blood loss, operative time, and perioperative complications were documented.

RESULTS

Twenty-seven patients underwent nephrectomy and 63 patients underwent nephroureterectomy. Thirty patients (33.3%) had perioperative complications. The majority of complications were of Clavien grade II. Six patients had Clavien Dindo grade III and none of the patients had grade IV complications. There were no significant differences in complication rates between right- and left-sided procedures (p = 0.233). Median blood loss was 190.1 ml and mean operative time was 227.1 minutes in nephrectomy and 256.6 minutes in nephroureterectomy. None of the patients had evidence of AVF formation on postoperative computerized tomography scan. Only three patients had a new diagnosis of heart failure. One of them was eventually lost to follow up. The remaining two patients had no evidence of AVF formation in imaging studies and physical examination.

CONCLUSION

En bloc ligation of the renal pedicle during laparoscopic nephrectomy and nephroureterectomy using a stapler is safe. None of our patients developed an AVF during follow up.

Name That Nephrogram: Asymmetric Renal Enhancement in the Acute Care Setting

Disorders of the kidney and urinary collecting system are common encountered in the acute care setting. Computed tomography has progressively replaced intravenous pyelography for the evaluation of most urinary tract pathology including acute flank pain, suspected malignancy, congenital abnormalities, anatomical variants, and inflammatory/vascular conditions through evaluation of the "nephrogram" produced by intravenous contrast material filtering through the kidneys. In this review, we describe the most common types of abnormal nephrograms seen on renal computed tomography, and highlight the salient features and conditions associated with them, in addition to a pictorial review with specific and interesting related cases. The types of abnormal nephrograms reviewed are absent, unilateral delayed, striated, spotted, and persistent.

Computed tomography and magnetic resonance imaging of peripelvic and periureteric pathologies

Peripelvic and periureteric areas are frequently overlooked in the imaging evaluations of the urinary system on computed tomography and magnetic resonance imaging. Several neoplastic and non-neoplastic disorders and diseases including lipomatosis, angiomyolipoma and angiolipomatous proliferation, vascular lesions, lymphangiomatosis, Rosai-Dorfman disease, Erdheim-Chester disease, extramedullary hematopoiesis, IgG4-related disease, lymphoma, mesenchymal tumors, trauma, and Antopol-Goldman lesion may involve these areas. Differentiation of these benign or malignant pathologies among themselves and from primary renal pathologies is of utmost importance to expedite the triage of patients for correct treatment approach. In this article, we aim to increase the awareness of the imaging specialists to the typical and atypical imaging features of the entities affecting these areas.

Enhancing in vivo renal ischemia assessment by high-dynamic-range fluorescence molecular imaging

Fluorescence imaging has been used to evaluate the physiological features of renal ischemia in animal model. However, the fluorophore distribution details of the ischemia model could not be fully represented due to the limited dynamic range of the charged-couple device. A high-dynamic-range (HDR) strategy was adopted in renal ischemia fluorescence imaging, both ex vivo and in vivo. The HDR strategy successfully combined ischemia relevant biological features that could only be captured with different exposure times, and then presented these features in the HDR results. The HDR results effectively highlighted the renal ischemic areas with relatively better perfusion and diminished the saturation that resulted from long exposure time. The relative fluorescence intensities of the ischemic kidneys and the image entropy values were significantly higher in the HDR images than in the original images, therefore enhancing the visualization of the renal ischemia model. The results suggest that HDR could serve as a postprocessing strategy to enhance the assessment of in vivo renal ischemia, and HDR fluorescence molecular imaging could be a valuable imaging tool for future studies of clinical ischemia detection and evaluation.

Hematuria as the only symptom at initial presentation of hypovolemic shock caused by ruptured renal arteriovenous malformations

Gross hematuria is a very common complaint in emergency departments and outpatient clinics. Globally, the incidence of hematuria is 4 per 1000 patients per year. Infection, urolithiasis, and neoplasm are the most common etiologies. However, hematuria rarely causes hypovolemic shock or an emergent, life-threatening condition at the initial presentation. In this report, we describe the case of a 64-year-old man who suffered a life-threatening gross hematuria in a very short time due to ruptured renal arteriovenous malformations (AVMs).

CT Imaging of Emergent Renal Conditions

The kidneys are paired intra-abdominal organs which provide essential functions and maintain homeostasis throughout the human body. Numerous disease processes affect the kidneys and cause acute renal dysfunction or other potentially catastrophic complications. These conditions can be broadly categorized into obstructive, infectious, hemorrhagic, traumatic, and vascular diseases. Imaging plays a vital role in the work-up and diagnosis of acute and emergent renal conditions. Evaluation of emergent renal conditions with a focus on CT imaging is discussed.

Clues to vascular disorders at non-contrast CT of the chest, abdomen, and pelvis

Non-contrast chest CT scans are commonly performed while CT scans of the abdomen and pelvis are performed in a select subset of patients; those with limited renal function, an allergy to iodinated contrast, in the setting of suspected renal calculus, retroperitoneal hematoma, common duct calculus, abdominal aortic aneurysm with or without rupture, and in patients undergoing a PET-CT scan. In the absence of intravenous contrast, vascular structures may prove challenging to evaluate, yet their assessment is an important component of every non-contrast CT examination. We describe the key imaging features of both arterial and venous pathology, and review clues and common associated non-vascular findings, which can help the radiologist identify vascular disorders at non-contrast CT. Briefly, alternative imaging options are discussed.

Renal Artery Stenosis: When to Revascularize in 2017

Atherosclerotic renal artery stenosis is the leading cause of secondary hypertension; it can also cause progressive renal insufficiency and cardiovascular complications such as refractory heart failure and flash pulmonary edema. Medical therapy including risk factor modification, renin-angiotensin-aldosterone system antagonists, lipid lowering agents, and antiplatelet therapy is the first line of treatment in all patients. Patients with uncontrolled renovascular hypertension despite optimal medical therapy, ischemic nephropathy, and cardiac destabilization syndromes who have severe renal artery stenosis are likely to benefit from renal artery revascularization. Screening for renal artery stenosis can be done with Doppler ultrasonography, computed tomographic angiography and magnetic resonance angiography. Invasive physiologic measurements are useful to confirm the severity of renal hypoperfusion and therefore improve the selection patients likely to respond to renal artery revascularization. Primary patency exceeds 80% at 5 years and surveillance for in-stent restenosis can be done with periodic clinical, laboratory, and imaging follow-up.

Management of Renovascular Hypertension

Renal artery stenosis is a potentially reversible cause of hypertension, and transcatheter techniques are essential to its treatment. Angioplasty remains a first-line treatment for stenosis secondary to fibromuscular dysplasia. Renal artery stenting is commonly used in atherosclerotic renal artery stenosis, although recent trials have cast doubts upon its efficacy. Renal denervation is a promising procedure for the treatment of resistant hypertension, and in the future, its indications may expand.

Imaging Manifestations of Hematologic Diseases with Renal and Perinephric Involvement

The kidneys and perinephric tissues can be affected by a variety of hematologic disorders, which usually occur in the setting of multisystem involvement. In many of these disorders, imaging is used to evaluate the extent of disease, guide biopsy, and/or monitor disease activity and patient response to therapy. Lymphoma, leukemia, and multiple myeloma commonly manifest as multiple parenchymal or perinephric lesions. Erdheim-Chester disease and Rosai-Dorfman disease, rare forms of multisystemic histiocytosis, are often identified as perinephric and periureteral masses. Renal abnormalities depicted at imaging in patients with sickle cell disease include renal enlargement, papillary necrosis, and renal medullary carcinoma. Sickle cell disease, along with other causes of intravascular hemolysis, can also lead to hemosiderosis of the renal cortex. Thrombosis of renal veins is sometimes seen in patients with coagulation disorders but more often occurs in association with certain malignancies and nephrotic syndrome. Immunoglobulin G4-related sclerosing disease is another multisystem process that often produces focal renal lesions, seen along with involvement of more characteristic organs such as the pancreas. Perinephric lesions with calcifications should raise the possibility of secondary amyloidosis, especially in patients with a history of lymphoma and multiple myeloma. Although the imaging patterns of renal and perinephric involvement are usually not specific for a single entity, and the same entity can manifest with different or overlapping patterns, familiarity with these patterns and key clinical and histopathologic features may help to narrow the differential diagnosis and determine the next step of care. (©)RSNA, 2016.

Acute Kidney Injury Associated with Renal Cell Carcinoma Complicated by Renal Vein and Inferior Vena Cava Involvement

Acute kidney injury (AKI) is caused by diverse pathologies, although it may occasionally result from concurrent renal efflux disturbances. We herein describe a case of AKI in a patient complicated by renal cell carcinoma (RCC) with renal vein and inferior vena cava (IVC) involvement. A neoplastic thrombus which disrupted the blood flow in the renal vein appeared to play a role in the rapid decline in the renal function. Such a scenario has rarely been mentioned in the previous literature describing the cases of RCC complicated by AKI. Concerns regarding the diagnostic and therapeutic strategies for RCC are also discussed.

Acute Urinary Tract Disorders

Acute urinary tract disorders often manifest as flank pain and are a common complaint of patients who present to the emergency department. The pain is often a vague, poorly localized sensation that may have a variety of causes. Laboratory and clinical findings, such as hematuria, are neither sensitive nor specific for determining the cause of the flank pain. Accordingly, imaging is an important tool in determining a diagnosis and management plan. Patients with acute urinary tract disorders who present with pain include those with calculi as well as renal infection, vascular disorders, and hemorrhage.

Contrast enhanced ultrasound (CEUS) in the diagnosis of post-partum bilateral renal cortical necrosis: a case report and review of the literature

Renal cortical necrosis is a rare condition with complex pathogenesis. There is no consensus over the best investigative modality for an initial diagnosis that is often in the context of acute renal failure. The applications of ultrasound contrast are ever growing, particularly with regard to the assessment of abdominal organs. Here, we present a case of post-partum bilateral renal cortical necrosis affecting bilateral native kidneys and the subsequent use of contrast enhanced ultrasound in confirming this diagnosis. The sonographic appearance was found to correlate with the patients' clinical presentation and other imaging findings. Secondarily, this allowed for appropriate and timely medical management and establishes the utility of ultrasound contrast in this clinical scenario. Contrast enhanced sonographic assessment should be considered early in patients with suspected renal vascular compromise. It is a safe, easy and efficacious investigative modality to stratify those patients with renal cortical necrosis from those with potentially reversible medical causes.

Atherosclerotic renal artery stenosis and revascularization

Atherosclerotic renovascular disease is the most common cause of secondary hypertension. The patients with renovascular disease are at increased risk for adverse cardiac outcomes. Recent trials comparing medical therapy alone to medical therapy with stenting are flawed, but lay to rest any existing debate that unselected revascularization is unwarranted; however, revascularization may be appropriate in high-risk populations. Defining an appropriate population for revascularization is an area of ongoing study. Furthermore, delivery of optimal medical therapy in this population is inadequate. This review describes recent developments in renal artery revascularization.

Imaging of iatrogenic complications of the urinary tract: kidneys, ureters, and bladder

Iatrogenic complications of various severities may arise from many, if not all, forms of medical and surgical treatment. Most of these occur in spite of proper precautions. Every system in the human body may be affected, and the urinary tract is no exception. Radiologists are often the first to suspect and identify such iatrogenic injuries and, therefore, awareness of the pertinent imaging findings is vital. This review explores and illustrates many of the common and less common iatrogenic complications affecting the kidney, ureters, and bladder.

Management of renal arteriovenous malformations: A pictorial review

Background

Arteriovenous malformations (AVMs) are communications between an artery and a vein outside the capillary level. This pathologic communication may be either a fistula, a simple communication between a single artery and a dilated vein, or a more complex communication, a nidus of tortuous channels between one or more arteries/arterioles and one or more draining veins. The latter type of lesion is most frequently seen in the extremities; in the kidney they tend to appear more rarely. The most common clinical presentation of renal arteriovenous malformations (RAVMs) is haematuria. Percutaneous treatment with selective endovascular techniques offers a minimally invasive, nephron-sparing option in comparison to the more invasive surgical approaches. The purpose of this pictorial review is to highlight the general lines of management and to show the range of imaging findings of the percutaneous treatment of RAVMs.

Methods

The imaging characteristics of a selection of cases of percutaneously managed congenital RAVMs are presented and the most common lines of approach are discussed.

Conclusion

The imaging spectrum of diagnosis and percutaneous treatment of RAVMs is presented in order to aid interpretation and endovascular management.

Teaching points

• Renal arteriovenous malformations are very rare lesions.

• Clinical expression is usually haematuria.

• Diagnosis is made with CT or MRI but the gold standard is digital subtraction angiography.

• Catheter-directed treatment with the use of coils or liquid embolics is minimally invasive, safe and effective.

A Case Of Acute Thromboembolic Renal Infarction Associated with Paroxysmal Atrial Fibrillation

Infarction of the kidney is an uncommon condition that can result from obstruction or decrease of renal arterial flow. The diagnosis is often delayed because it can mimic many other pathologic states, including pyelonephritis, renal colic, acute abdomen, pancreatitis and more. A high index of suspicion is important for prompt diagnosis. We describe a 20-year-old man presented with abdominal and right flank pain and hematuria. A computed tomography scan with intravenous contrast showed partial infarction of right renal parenchyma and selective renal angiography showed complete occlusion of the right renal artery which was also supplied by an accessory renal artery. Electrocardiography showed normal sinus rhythm. Transthoracic and transesophageal echocardiographic findings were unremarkable except for mild spontaneous echo contrast (SEC) in the left atrial appendage. Subsequent 48-hour holter monitor revealed frequent premature atrial complexes and paroxysmal atrial fibrillation (PAF). Development of thromboembolic renal infarction was attributed to the presence of PAF and concurrent SEC in the left atrial appendage (LAA). Low molecular weight heparin(LMWH) was followed by oral anticoagulant and an electrophysiologic study was planned for the management of PAF after 4 weeks of anticoagulation.