Three-dimensional CT angiography: renal applications

Endovascular management of a large renal artery aneurysm: a case report and review of the literature

Background

A renal artery aneurysm is a rare clinical presentation that can be found incidentally on imaging or during workup for refractory hypertension. Its presentation can be similar to that of a renal artery pseudoaneurysm, but the etiologies of the two vascular lesions differ. We present a patient who had an incidental finding of a large renal artery aneurysm that was managed with endovascular embolization. We also describe the literature surrounding the etiology, presentation and management of both renal artery aneurysms and renal artery pseudoaneurysms.

Case presentation

A 62-year-old man was referred to a urologic oncologist for workup of a newly found renal mass. Initial imaging with computed tomography showed a homogenous, well-circumscribed mass arising from the right kidney. Further evaluation with Doppler ultrasonography demonstrated pulsatile flow within the renal mass that was concerning for a renal artery pseudoaneurysm. The patient initially underwent a diagnostic angiogram by interventional radiology and was found to have a true renal artery aneurysm. Interventional radiology considered placement of a covered stent or angioembolization, but treatment was deferred due to concern for compromising the patient’s renal function. Patient was subsequently transferred to a neighboring hospital for management by vascular surgery. After considering both open surgical and endovascular approaches, the patient ultimately underwent angioembolization of the renal artery aneurysm. Short-term follow-up showed successful exclusion of the aneurysm with minimal adverse effects to the patient.

Conclusions

Our case report documents a unique case of an incidentally found large renal artery aneurysm that was successfully managed with endovascular embolization. Renal artery aneurysms and renal artery pseudoaneurysms, which can present similarly on imaging, are important diagnostic considerations in a patient presenting with a new renal mass. While open surgical approaches can be used to repair aneurysms, endovascular approaches using stenting or angioembolization are safe and effective options for treating renal aneurysms and renal pseudoaneurysms.

Normal Anatomy and Variants of Renal Vasculature with Multidetector Computed Tomography in a Tertiary Care Hospital: A Descriptive Cross-sectional Study

Introduction:

Preoperative multisection computed tomography evaluation can provide necessary anatomic information in minimally invasive surgeries. This study was done to estimate the prevalence and pattern of variations of renal vasculature through contrast-enhanced computed tomography in patients referred to the radiology department of a tertiary care hospital.

Methods:

A descriptive cross-sectional study was conducted from 6th April 2016 to 6th April 2017. Ethical approval was taken. The triple-phase contrast-enhanced computed tomography was performed on 188 patients enrolled through convenient sampling. The images were evaluated in unenhanced, arterial, and venous phases for the vascular variants. Data were analyzed based on the anatomical types of variations and descriptive statistics such as frequency and percentage using the Statistical Package for the Social Sciences.

Results:

Out of the 188 patients, 60 (31.9%) had accessory renal arteries. The most common variant was hilar arteries which comprised 38 cases (20.2%) whereas polar arteries were present in 21 (11.1%) cases and the capsular artery was present in one (0.5%) case. Early bifurcation of the renal artery was noted in 15 (8%) cases with 10 (5.3%) on the right and 5 (2.7%) on the left side. Twelve (6.3%) cases of the double right renal vein were noted whereas retroaortic left renal vein was noted in only 4(2.1%) cases.

Conclusions:

Based on our study, almost one in three patients had accessory renal arteries and eighty-five out of a thousand patients had variants of renal veins.

Angio CT assessment of anatomical variants in renal vasculature: its importance in the living donor

BACKGROUND

Renal vasculature is known for having a broad spectrum of variants, which have been classically reported by anatomists.

METHODS

The distribution and morphology of these variations can be explained by considering the embryology of the renal vessels. With the recent outburst of imaging techniques, it has been the radiologist's turn to take the baton, recognising and describing unconventional renal vascular patterns.

RESULTS

Knowledge of these patterns has gained significance since the advent of the era of transplantation. For almost 60 years cadaveric donation has been the main source of kidneys suitable for transplantation. Living kidney donation demonstrates many advantages and stands out as the best alternative for organ procurement to meet the increasing demand. Since the dawn of laparoscopic nephrectomy as the technique of choice for organ procurement in living kidney donors, MDCT plays a key role as a noninvasive preoperative planning method for anatomic evaluation. As the field of view at laparoscopic surgery is limited, it is essential to meticulously assess the origin, number, division and course of arteries and veins.

CONCLUSION

Awareness of the different anatomical variants allows the radiologist to enlighten the surgeon in order to avoid compromising the safety of the surgical procedure that could lead to significant complications.

TEACHING POINTS

• Renal vasculature has many variants, which can be explained by considering the embryology of kidneys. • Living kidney donation demonstrates many advantages over cadaveric donation. • Angio CT evaluation of living kidney donors is a multiple phase study. • A detailed report describing the variants, their distribution and morphology will help surgeons.

Renal artery aneurysm mimicking renal calculus with hydronephrosis

A 51-year-old woman was found to have a left renal calculus with hydronephrosis. She underwent unsuccessful extracorporeal shock wave lithotripsy, leading to the recommendation that percutaneous lithotomy was necessary to remove the renal calculus. In view of the unusual shape of the calculus and absence of abnormalities in urine sediment, preoperative computed tomography and renal angiography were performed, which instead showed a calcified left renal artery aneurysm. Subsequent efforts to perform an aneurysmectomy also failed, eventually necessitating left nephrectomy. This case illustrates the pitfalls in the diagnosis of a renal artery aneurysm, which is a relatively common condition that may have unusual presentations. Hence, it is suggested that the possibility of a renal artery aneurysm be considered in the differential diagnosis when one detects a renal calculus with an unusual appearance. In addition, we propose that 3-dimensional reconstruction computed tomography be performed before considering surgical options for such renal calculi to rule out the possibility of a renal artery aneurysm.

Origination angle of renal artery has no role in renal artery pattern

INTRODUCTION

Renal artery (RA) anatomy plays a critical role in selecting donors. During the present study, we sought to evaluate the physiological role of RA origination angle for the presence of an accessory RA or its early branching.

METHODS

During the present cross-sectional study (August 2005-October 2007), 143 candidates for kidney donation underwent RA angiography by 64 multidetector computed tomographic angiography. We assessed the RA diameter, distance to first branching, presence of accessory RA, and early branching, as well as the origination angle of RA from aorta in coronal plane (alpha angle).

RESULTS

The male-to-female ratio was 96:47 with an overall mean age of 27.42 +/- 4.55 years. The alpha angle, sine, cosine of the alpha angle and the deviation factor were not significantly different between kidneys with versus without an accessory artery or between the RA with versus without an early branching. Only the RA diameter (P = .047) and the distance of RA to the branching (P < .001) in kidneys with an accessory RA were significantly lower and higher than those without an accessory RA, respectively. Also the distance of the RA to the branching was significantly less in kidneys with an early branching (P < .001). The RA diameter directly correlated with the RA origination angle (r = .191, P = .001), while there was no correlation between the distance to RA branching and the RA origination angle (r = -.060, P = .311).

CONCLUSION

The origination angle of the RA from aorta has no role in the early branching or accessory RA development. There was a direct correlation between the RA diameter and the RA origination angle.

Intrarenal post-traumatic pseudoaneurysm-USG colour Doppler diagnosis: a case report with review of literature

Renal artery pseudoaneurysm, although a well-known complication in patients after penetrating trauma or iatrogenic injury, has rarely been described after blunt torso trauma. A 22-year-old man suffered an accident while on a motorcycle. Upon arrival in the Emergency Room, the patient was unconscious, hypotensive and had hematuria. Initial investigations revealed a fractured shaft of the right femur, multiple rib fractures with hemothorax, extradural haematoma on the right side and a laceration in the right kidney. After the evacuation of intracranial bleed, the patient was managed conservatively. The patient recovered well and was discharged on the 15th post-trauma day. The patient was again present in the emergency room after 6 weeks with 1-week history of gross hematuria. Ultrasonography revealed an anechoic lesion in the right kidney with pulsatile flow on colour Doppler. Further investigation with computed tomography renal angiography was done, which confirmed the pseudoaneurysm of a branch of renal artery. The patient was referred to a higher centre where he was successfully managed with selective arterial coil embolisation.

Multidetector spiral CT renal angiography in the diagnosis of renal artery fibromuscular dysplasia

OBJECTIVE

The aim of this study was to evaluate the role and detection rate of multidetector spiral CT renal angiography (CTA) as compared with conventional angiography (CA), the commonly accepted gold standard, in the diagnosis of renal artery fibromuscular dysplasia (FMD). In addition, the role of CTA reconstructions (multiplanar reformatted images (MPR), maximum intensity projections (MIP) and shaded-surface display (SSD)) in the detection of FMD was also evaluated.

MATERIALS AND METHODS

CTA results were retrospectively reviewed in 21 hypertensive patients with CA-proven FMD. Clinical indications for referral included resistant hypertension (requiring greater than three antihypertensive medications), labile hypertension, hypertension in combination with renal impairment and the presence of abdominal bruits in the context of systemic hypertension. In some cases, these clinical indications were supplemented by positive results in other tests, including plasma renin assay, captopril scintigraphy and/or Doppler ultrasound. The findings of CA in these 21 patients were compared to CTA.

RESULTS

Mean patient age was 62.33+14.32 years (range 24-85 years). CTA identified all 42 main renal arteries (100%) and all 10 accessory renal arteries (100%) visualized on CA. In the diagnosis of FMD, CTA detected all 40 (100%) lesions detected by CA. No single CTA reconstruction technique was able to detect all lesions noted on corresponding CA, however, upon review of all CTA reconstructions (MPR, MIP and SSD) in each case, every lesion was correctly identified by CTA.

CONCLUSION

Our experience suggests that CTA is a non-invasive, reliable and accurate method for the diagnosis of renal artery fibromuscular dysplasia. Moreover, in our experience CTA has many advantages as a diagnostic screening tool over CA, including accessibility, speed, lower complication profile, versatility and cost-effectiveness. CTA shows great potential as a guiding tool for directing subsequent procedures such as CA+balloon angioplasty.

Surgically Relevant Normal and Variant Renal Parenchymal and Vascular Anatomy in Preoperative 16-MDCT Evaluation of Potential Laparoscopic Renal Donors

OBJECTIVE

Using 16-MDCT, we describe and quantify the frequency and types of renal anatomic variants and findings relevant for preoperative evaluation and surgical planning for potential laparoscopic renal donors.

MATERIALS AND METHODS

On 16-MDCT, 126 consecutive potential donors underwent scanning before contrast administration and after i.v. power injection of nonionic contrast material during the arterial, nephrographic, and excretory phases. On a 3D workstation, CT images were evaluated retrospectively in consensus by three abdominal imagers. The number and branching pattern of bilateral renal arteries and veins, including anomalies of the inferior vena cava and lumbar-gonadal axis, were categorized along with the frequency of incidental findings of the renal parenchyma and collecting system.

RESULTS

Major arterial variants including supernumerary and early branching arteries were present in 16% and 21%, respectively, of left kidneys and 22% and 15%, respectively, of right kidneys. Major and minor venous variants were detected in 11% and 58% of left kidneys and 24% and 3% of right kidneys. Late confluence of the venous trunk was identified in 17% of left kidneys and 10% of right kidneys. Incidental parenchymal and urothelial abnormalities, most commonly cysts and calyceal calcifications, were identified in 30% of the kidneys. Other relevant incidental findings included focal infarcts, cortical scars, atrophic scarred kidney, and bilateral papillary necrosis. Urothelial variants included bilateral simple ureteroceles and rightsided complete duplicated collecting system.

CONCLUSION

16-MDCT angiography and urography allow confident detection and classification of a variety of anatomic and incidental anomalies relevant to the preoperative selection of potential laparoscopic renal donors and to surgical planning.

Multidetector spiral CT renal angiography in the diagnosis of giant renal artery aneurysms

A case of giant renal artery aneurysm in a 63-year-old man is presented. Renal artery aneurysms are rare (incidence of <1%) and this case is one of the largest giant renal artery aneurysms recorded in the literature. This case also demonstrates the value of multidetector spiral CT renal angiography (CTA) in the diagnosis, planning and treatment of renal aneurysms.

Multidetector spiral CT renal angiography in the diagnosis of giant renal artery aneurysms

A case of giant renal artery aneurysm in a 63-year-old man is presented. Renal artery aneurysms are rare (incidence < 1%) and this case is one of the largest giant renal artery aneurysms recorded in the literature. This case also demonstrates the value of multidetector spiral computed tomographic renal angiography in the diagnosis, planning, and treatment of renal aneurysms.

Adult Ureteropelvic Junction Obstruction: Insights with Three-dimensional Multi–Detector Row CT

Ureteropelvic junction obstruction (UPJO) is a benign, congenital condition that remains an enigma in terms of both diagnosis and therapy. On the basis of a series of cases that were referred to the authors in their clinical practice, they found that the unprecedented quality and novel perspectives of multi-detector row computed tomography (CT) with two- and three-dimensional postprocessing allow a comprehensive, single-study assessment of the ureterovascular relationships in UPJO. This topic is important because the causative role of crossing vessels may be questioned on the basis of such studies, and the therapeutic approach may be altered by using precise anatomic images customized to the pathologic features of the individual patient. Although CT images can provide only circumstantial or supportive evidence of the pathophysiology of UPJO, they greatly facilitate therapeutic intervention when it is clinically indicated and may eliminate the need for it in select cases. Careful attention to the postprocessing of CT images may show that the crossing vasculature has no direct relationship to the transition point of the UPJO in many cases.

Multi-detector row CT evaluation of living renal donors prior to laparoscopic nephrectomy

Since its introduction in 1995, laparoscopic nephrectomy has become the preferred technique at many medical centers for the harvesting of kidneys from living donors for transplantation. Because the field of view at laparoscopic surgery is limited, preoperative radiologic evaluation of the donor's anatomy---the renal veins and arteries, collecting system, and parenchyma--is critical. Spiral computed tomographic (CT) angiography is a fast, safe, minimally invasive, and generally accepted method for preoperative evaluation of the renal vessels. Multi-detector row CT scanners offer shorter image acquisition time, narrower collimation, better spatial resolution, and less tube heating than do single-detector row CT scanners. Multi-row scanners also provide more complete anatomic coverage, increased contrast enhancement of the arteries, and greater longitudinal spatial resolution--all of which are important both for accurate imaging of the renal vasculature and for three-dimensional postprocessing of image data. Dual-phase multi-detector row CT angiography combined with three-dimensional postprocessing enables minimally invasive and highly accurate depiction of the preoperative donor anatomy. To make the most effective use of this method, radiologists must be familiar with its technical aspects, advantages, and potential pitfalls. They also must be able to identify variations in vasculature and in renal and extrarenal anatomy that are important for laparoscopic donor nephrectomy.

Multidetector CT angiography for preoperative evaluation of living laparoscopic kidney donors

OBJECTIVE

The purpose of this study was to determine the accuracy of multidetector CT (MDCT) angiography as the primary imaging technique in the evaluation of living kidney donors.

SUBJECTS AND METHODS

Seventy-four consecutive living kidney donors (30 men, 44 women; mean age, 41.7 years) who underwent MDCT were evaluated. CT examination was performed with 120 mL of IV contrast material at an injection rate of 3 mL/sec and a pitch of 6. In every case, arterial and venous phase volumetric data sets were acquired at 25 and 55 sec, respectively. Scans were reconstructed at 1-mm intervals for three-dimensional (3D) imaging using a volume-rendering technique. Axial CT images and 3D CT angiography were evaluated prospectively by one reviewer and retrospectively by two reviewers who had no knowledge of surgical results. Surgical correlation for the location of primary and accessory renal arteries, early branching of the renal arteries, and renal vein anomalies was made.

RESULTS

Seventy-two subjects underwent left nephrectomy, and two subjects underwent right nephrectomy because supernumerary left renal arteries were detected on preoperative CT angiography. Eighteen supernumerary renal arteries (two arteries to 16 kidneys and three arteries to one kidney) to 74 kidneys underwent nephrectomy. CT and surgical findings agreed in 93% of subjects (the average of three reviewers; range, 89-97%). Two small accessory renal arteries were missed by all three reviewers. Those arteries were diminutive and were thought to be insignificant by the surgeons. Early branching of the renal arteries was shown in 14 arteries, and CT and surgical findings agreed in 96% (the average of three reviewers; range, 93-97%). Renal vein anomalies were present in eight subjects, and CT and surgical findings agreed in 99% of the cases (range, 96-100%).

CONCLUSION

MDCT angiography is highly accurate for detecting vascular anomalies and providing anatomic information for laparoscopic living donor nephrectomy.

Parameters affecting bolus geometry in CTA: a review

CT angiography (CTA) is based on acquisition of data during the arterial phase of contrast material passage. CTA needs timing of the contrast bolus, which should be based on accurate knowledge of bolus geometry. Experimental and human studies on bolus geometry and bolus timing in CTA were reviewed. Important parameters of bolus geometry and methods of bolus timing (test bolus and bolus tracking) are described. Recommendations are given for an optimal CTA protocol.

Three-dimensional volume-rendered CT angiography of the renal arteries and veins: normal anatomy, variants, and clinical applications

Three-dimensional volume-rendered computed tomographic (CT) angiography represents an increasingly important clinical tool that, in many institutions, is replacing conventional angiography in the depiction of normal vascular anatomy and the diagnosis of vascular disorders. Evaluation of conditions affecting the renal vasculature constitutes a major focus of volume-rendered CT angiography, which has documented utility for demonstrating both arterial and venous disease. Arterial disorders include renal artery stenosis, renal artery aneurysms, and dissection. Venous disorders include splenorenal shunts, thrombosis, and intravascular tumor extension. In addition, volume-rendered CT angiography accurately displays the normal and variant renal vascular anatomy, which is crucial to detect before surgery, especially partial nephrectomy and laparoscopic nephrectomy. CT angiography is also useful in the evaluation of the renal vasculature following renal transplantation. Familiarity with proper CT protocols and data acquisition techniques are crucial for accurate diagnosis.

Renal mass within a horseshoe kidney: preoperative evaluation with three-dimensional helical computed tomography

Tumors arising within a horseshoe kidney are uncommon and may be difficult to characterize. We report a case of transitional cell carcinoma in a horseshoe kidney. Although several conventional imaging techniques were used to define the mass, each provided limited information. Recent advances in computer technology permit radiologic imaging to provide detailed examination of the horseshoe kidney with a single study. We describe the use of three-dimensional multislice helical computed tomography as the preferred modality to clarify the suspected neoplasm, vasculature, and collecting system of a horseshoe kidney. High-quality anatomic characterization will certainly enhance the opportunity for nephron-sparing surgery within this population.

Multislice CT angiography

Multislice CT has overcome past limitations of CT angiography (CTA): Scan length and spatial resolution can be simultaneously optimized with multislice CTA, contrast medium can be saved, and the evaluation of large anatomic areas and vessels smaller than 1 mm become possible. This article describes how to optimize scanning protocols and contrast injection, and discusses the main clinical applications of this new technique. Only three main scanning protocolssuffice for all indications. A high speed / high-volume protocol (using 4*2mm or 4*2.5mm collimation) can be employed to scan the chest or abdomen in 8-10s, or to cover the whole abdominal aorta and the peripheral runoff including the feet within 40-65s. A high resolution protocol (using 4*1mm or 4*1.25mm) can be employed for the aorta and most regional vascular beds. It allows for near isotrophic imaging and depicts fine vascular structures with excellent detail. Ultra-high resolution protocols (using 2*0.5mm or 4*0.5mm collimation) yield totally isotropic data sets, and are mainly reserved for cerebrovascular imaging. Image processing techniques, and, in particular, volume rendering have made image presentation faster and easier. Multislice CTA exceeds MRA in spatial resolution and is now able to display even small vascular side branches. Its main indications will be aortic diseases, suspected pulmonary embolism but also renal artery stenoses, preoperative workup of abdominal or cerebral vessels, and acute vascular diseases. Multisplice CTA will become a strong competitor of other minimally invasive vascular imaging techniques.