Assessment of the kidney tumor vascular supply by two-phase MDCT-angiography

Extrarenal Visceral Arteries Injuries during Left Radical Nephrectomy: A 50-Year Continuing Problem

Due to their proximity to the left renal hilum, injuries to the superior mesenteric artery and celiac trunk are still reported during left radical nephrectomy, whether performed via open, laparoscopic, or robotic methods. The aim of this 50-year narrative review is to emphasize the anatomical and pathophysiological bases, risk factors, and strategies for the prevention, diagnosis, and treatment of such injuries.

Elastohydrodynamic autoregulation in soft overlapping channels

Controlling fluid flow from an unsteady source is a challenging problem that is relevant in both living and man-made systems. Animals have evolved various autoregulatory mechanisms to maintain homeostasis in vital organs. This keeps the influx of nutrients essentially constant and independent of the perfusion pressure. Up to this point, the autoregulation processes have primarily been ascribed to active mechanisms that regulate vessel size, thereby adjusting the hydraulic conductance in response to, e.g., sensing of wall shear stress. We propose an alternative elastohydrodynamic mechanism based on contacting soft vessels. Inspired by Starling's resistor, we combine experiments and theory to study the flow of a viscous liquid through a self-intersecting soft conduit. In the overlapping region, the pressure difference between the two channel segments can cause one pipe segment to dilate while the other is compressed. If the tissue is sufficiently soft, this mode of fluid-structure interactions can lead to flow autoregulation. Our experimental observations compare well to a predictive model based on low-Reynolds-number fluid flow and linear elasticity. Implications for conduit arrangement and passive autoregulation in organs and limbs are discussed.

Modeling Neoplastic Growth in Renal Cell Carcinoma and Polycystic Kidney Disease

Renal cell carcinoma (RCC) and autosomal dominant polycystic kidney disease (ADPKD) share several characteristics, including neoplastic cell growth, kidney cysts, and limited therapeutics. As well, both exhibit impaired vasculature and compensatory VEGF activation of angiogenesis. The PI3K/AKT/mTOR and Ras/Raf/ERK pathways play important roles in regulating cystic and tumor cell proliferation and growth. Both RCC and ADPKD result in hypoxia, where HIF-α signaling is activated in response to oxygen deprivation. Primary cilia and altered cell metabolism may play a role in disease progression. Non-coding RNAs may regulate RCC carcinogenesis and ADPKD through their varied effects. Drosophila exhibits remarkable conservation of the pathways involved in RCC and ADPKD. Here, we review the progress towards understanding disease mechanisms, partially overlapping cellular and molecular dysfunctions in RCC and ADPKD and reflect on the potential for the agile Drosophila genetic model to accelerate discovery science, address unresolved mechanistic aspects of these diseases, and perform rapid pharmacological screens.

Decreased capillary density in renal cell carcinoma: Evidence from a case report with micro-computerized tomography

RATIONALE

Conventional computerized tomography (CT) examination can differentiate renal cortical tumor from urothelial carcinoma on the basis of the highly contrast-enhanced vessels in renal cortical tumors. However, the capillary distribution of renal cell carcinoma (RCC) has been under-investigated. Here, we present a micro-CT image of tumor tissue in a patient with RCC.

PATIENT CONCERNS

The patient was a 72-year-old woman with a past history of diabetes mellitus and hypertension. She did not have tumor-related symptoms.

DIAGNOSIS AND INTERVENTIONS

The tumor was diagnosed using abdominal CT during her yearly routine health check. After radical nephrectomy, the tumor was subjected to pathological examination and micro-CT imaging. Pathological analysis confirmed a clear cell renal carcinoma. The capillary distribution of the tumor was significantly lesser than that of the normal cortex on micro-CT image.

LESSONS

Microvessels of RCC can be detected by micro-CT. We also found that the distribution of microvessels was uneven and lower than that in the normal cortex in this case. For a more general diagnosis, more micro-CT images of RCC tumors are needed.

Perihilar branching patterns of renal artery and extrarenal length of arterial branches and tumour-feeding arteries on multidetector CT angiography

OBJECTIVE

The purpose of our study was to assess the extrarenal length of renal arterial branches and tumour-feeding arteries on multidetector CT (MDCT) angiography, in addition to the perihilar branching patterns, with relevance to segmental artery clamping.

METHODS

MDCT angiograms of 64 patients with renal masses <4 cm were retrospectively reviewed by 2 radiologists. The perihilar branching patterns of the single main renal artery were assessed according to the number of pre-segmental and segmental arteries. The extrarenal lengths of segmental plus pre-segmental arteries and the tumour-feeding arteries, measured on volume-rendered images, were compared according to the vascular segmentation and the tumour location, respectively.

RESULTS

In the 116 kidneys, 1 pre-segmental plus 5 segmental arteries (n=48) was the most common branching pattern. The mean extrarenal length of the inferior segmental plus pre-segmental arteries (33.05 mm) and the posterior segmental plus pre-segmental arteries (32.30 mm) was longer than any of the other segmental plus pre-segmental arteries (apical, 23.87 mm; superior, 26.80 mm; middle, 29.23 mm) (p<0.05). The mean extrarenal length of the lower pole tumour-feeding arteries (35.94 mm) was longer than those of the upper and mid-pole tumour-feeding arteries (24.95 mm, 29.62 mm), with significant difference between the lower and the upper pole tumour-feeding arteries (p<0.05).

CONCLUSION

Tumours in the lower pole, supplied by the inferior or posterior segmental artery, may be more amenable to segmental artery clamping.

ADVANCES IN KNOWLEDGE

MDCT angiography with volume rendering can demonstrate the extrarenal length of tumour-feeding arteries and may help in determining the accessibility for segmental artery clamping.

CT angiography of the renal circulation

Although catheter angiography remains the accepted gold standard for imaging of the renal vascular system, rapid progress in cross-sectional imaging techniques has caused a paradigm shift in many diagnostic algorithms toward noninvasive techniques such as computed tomographic angiography (CTA). CTA's cross-sectional imaging techniques provide an opportunity for comprehensive renal investigation that would be impossible with angiography alone. While other competing noninvasive technologies such as ultrasound and magnetic resonance angiography can be used successfully in renal imaging, the benefits of CTA are substantial, including high spatial and temporal resolution, widespread availability, implantable device compatibility, and easy technical reproducibility. This article describes the technical considerations relevant to CTA of the renal vascular system, postprocessing algorithms for volumetric data, and numerous specific applications.