Magnetic resonance imaging of the abdominal aorta and iliac vessels using combined 3-D gadolinium-enhanced MRA and gadolinium-enhanced fat-suppressed spoiled gradient echo sequences

Complications of transplantation. Part 1: renal transplants

Vascular complications after solid-organ transplantation are not uncommon and may lead to graft dysfunction and ultimately graft loss. A thorough understanding of the surgical anatomy, etiologies, and types of vascular complications, their presentation, and the options for management are important for managing these complex patients. This article reviews the basic surgical anatomy, vascular complications, and endovascular management options of vascular complications in patients with renal transplants.

Management of transplant renal artery stenosis

Transplant renal artery stenosis is the most frequent vascular complication of transplantation. Early detection and correction reduce patients' morbidity and allograft dysfunction. Although noninvasive imaging can detect an underlying stenosis, angiography with subsequent angioplasty or stenting, or both, provides definitive diagnosis and treatment. With the introduction of alternative contrast agents and newer catheter and stent technology, these procedures can be performed safely with little risk of contrast-induced nephropathy or allograft loss.

Basics of magnetic resonance imaging

In clinical diagnostic imaging there has been a rapid evolution of nuclear magnetic resonance techniques. A subset of these has proven particularly powerful when applied to the arena of noninvasive vascular imaging. This article will serve as a primer for practitioners with little prior background in magnetic resonance angiography (MRA). It will develop the first principles of magnetic resonance image creation, and establish familiarity with current imaging applications of the thoracic, abdominal, and peripheral vasculature.

Assessment of aorto-iliac disease with magnetic resonance angiography using arterial phase 3-D gradient-echo and interstitial phase 2-D fat-suppressed spoiled gradient-echo sequences

PURPOSE

To evaluate magnetic resonance angiography (MRA) of the pelvis for the examination of the aorto-iliac system using arterial phase 3-D gradient echo and interstitial phase 2-D fat-suppressed spoiled gradient-echo (SGE), with comparison to surgery and angiography.

MATERIALS AND METHODS

Ninety MR angiograms performed on 79 consecutive patients were analyzed, retrospectively, for the presence of narrowing, aneurysm, and dissection. Comparisons were made with angiography and surgery in 50 examinations, and a weighted kappa statistic test was applied to assess agreement. MR examinations were performed at 1.5T 3-D fast imaging in steady state precession (FISP) acquired immediately, and fat-suppressed SGE in the interstitial phase following gadolinium administration.

RESULTS

MRA had overall sensitivities of 100% at aortic segments, 100% at common iliac, 93.8% at external, and 95.7% at internal iliac, and specificities of 100% at aortic segments, 89.7% at common iliac, 95.2% at external iliac, and 88.7% at internal iliac in detection of vascular disease. The agreement of MRA with the angiography and surgery yielded a weighted kappa statistic of 0.97 at the aortic, 0.94 at the common, 0.85 at the external, and 0.82 at the internal iliac segments.

CONCLUSION

This study demonstrates an excellent performance of MRA in the evaluation of aorto-iliac arterial system and almost perfect agreement with angiography and surgery at all vascular levels.

Amenorrhoea revealing an arteriovenous uterine malformation, and recovery of menses after embolization

A case is reported of secondary amenorrhoea related to an arteriovenous malformation (AVM) successfully treated with embolization, with a recovery of menstrual cycles. A 28-year-old woman presented with secondary amenorrhoea as the only clinical symptom. Although she had an eugonadic status, there was no genital withdrawal bleeding upon cessation of an oral contraceptive. Pelvic transvaginal ultrasonography revealed a pelvic mass but magnetic resonance imaging (MRI) clearly showed an AVM. Classical angiography was performed with endovascular embolization. Partial thrombosis of the lesion was assessed by magnetic resonance angiography. Recovery of menses occurred 2 months later. It is speculated that blood stolen from the endometrium by the uterine AVM could have been responsible for the amenorrhoea. It is a very unusual cause, and it can be successfully treated with embolization.

Magnetic resonance imaging of thoracic aortic aneurysm and dissection

MRI is an extremely useful technique for the evaluation of the thoracic aorta. It provides a comprehensive evaluation of all the important structures within the chest and allows for high-resolution imaging of both the aortic lumen and the wall itself. As such, it is a sensitive method for delineating the extent of disease, branch-vessel involvement, and superimposed complications. Technical advances, such as stepped-table MRA and bolus-timing strategies, continue to improve overall image quality. In addition, the recent development of blood-pool contrast agents may further impact the diagnostic yield. Given these facts, MRI is likely to remain a mainstay in this patient population for years to come.

Angiographic evaluation and treatment of transplant renal artery stenosis

Transplant renal artery stenosis is an uncommon but important complication of renal transplantation. It is a potentially reversible cause of patient morbidity and allograft dysfunction, which can present both early and late in the post-transplant period. Although transplant renal artery stenosis can be detected using noninvasive imaging, definitive diagnosis and percutaneous treatment typically require the use of invasive angiographic techniques. In experienced hands, these studies can be performed safely, effectively and with a low risk of contrast induced nephrotoxicity when alternative contrast agents are used.