A prospective study of the predictive power of spiral computed tomographic angiography for defining renal vascular anatomy before live-donor nephrectomy

OBJECTIVE: To determine the accuracy of spiral computed tomography (CT) imaging of donor venous anatomy by comparing CT angiography (CTA) and operative findings, for both laparoscopic (LDN) and open donor nephrectomy. PATIENTS AND METHODS: LDN presents unique surgical challenges, particularly with complex venous or arterial anatomy. The limitations of surgical access, poor visibility of the superior and posterior borders of the renal vein during LDN, and the variability of venous anatomy in this region, contribute to the difficulty of LDN, underlining the importance of imaging beforehand. Forty live donors (mean age 46 years, sd 11; 65% female) were assessed by CTA before donation. Scans were reported by the same radiologist. The number and diameter of 'predicted' renal arteries, veins and renal vein tributaries were documented. The donor kidney was removed by two consultant surgeons, and after back-table perfusion the same details were recorded and taken as the 'reference' findings. Tributaries of <1 mm diameter were not recorded. The right kidney was retrieved in seven patients; 25 of the 40 kidneys were retrieved by LDN and the other 15 by open surgery. RESULTS: In all, 48 actual renal arteries were identified at nephrectomy; of these, 47 were predicted by CTA. Likewise, 41 actual renal veins were found at nephrectomy, 40 of which were predicted. The overall accuracy of spiral CTA in predicting the presence or absence of renal vein tributaries was 83% for gonadal and adrenal veins, and 75% for lumbar veins. There were seven false-negative lumbar veins found at nephrectomy; in these cases the CTA films were retrospectively examined, and five of these seven veins were identified. The predicted renal vein tributary diameter correlated poorly with the measured diameter at nephrectomy. CONCLUSIONS: Assessing potential renal donors before surgery with spiral CTA provides an accurate prediction of the presence or absence of the gonadal and adrenal vein, but is less accurate for predicting lumbar veins. This is especially pertinent as the posterior lumbar tributaries have the most intra-individual variation, and are the most difficult to display and control at LDN. This highlights the need for meticulous dissection of the renal vein, particularly along its posterior wall.     

Intravenous digital subtraction angiography and helical computed tomography in evaluation of living renal donors

OBJECTIVES: The present study was carried out to evaluate the accuracy of helical computed tomography (CT) and intravenous digital subtraction angiography (IV-DSA) on anatomical assessment of renal vasculature for living renal donors. METHODS: Forty-two healthy potential renal donors were prospectively evaluated and 35 subsequently underwent donor nephrectomy after helical CT and IV-DSA evaluation. The vascular and non-vascular findings were compared between the findings on helical CT, IV-DSA and surgery. RESULTS: Ten prehilar branches and five accessory renal arteries were found at nephrectomy. Overall, operative findings agreed with the findings by IV-DSA in 89% and by helical CT in 83%. In delineating accessory arteries, IV-DSA had a sensitivity of 60% and specificity of 97%, whereas helical CT had a sensitivity of 40% and specificity of 100%. In delineating prehilar branches, IV-DSA had a sensitivity of 90% and specificity of 100%, whereas helical CT had a sensitivity of 70% and specificity of 100%. Accessory arteries and prehilar branches that were not detected by helical CT or IV-DSA, were less than 2 mm in diameter and did not require vascular reconstruction. Renal veins were delineated in 63% by IV-DSA, whereas they were clearly imaged by helical CT in all cases, including a case with a circumaortic renal vein. Non-vascular findings were obtained in 64% by helical CT, including two renal tumors. None of these findings were obtained by IV-DSA. CONCLUSION: Helical CT and IV-DSA provide comparably sufficient information on renal artery vasculature. However, helical CT provides significantly more information on venous and non-vascular findings as a single-imaging modality.     

Magnetic resonance renal angiography and venography: an analysis of 111 consecutive scans before donor nephrectomy

OBJECTIVE: To determine the accuracy of magnetic resonance imaging (MRI) renal angiography in predicting vascular anatomy before donor nephrectomy, to determine the significance of missed vessels and to ascertain whether vessels are missed because of technical limitations or errors in interpretation. PATIENTS AND METHODS: In all, 111 consecutive living donations were assessed; the anatomy on MRI before donation was compared with that at nephrectomy. The significance of additional arteries and veins was recorded at the time of donation, with extra vessels either anastomosed or sacrificed. Finally, the scans in which extra vessels had not been identified were re-examined to establish whether these could be identified retrospectively. RESULTS: In all, 93 kidneys had a single renal artery and 18 had two. All lower pole arteries were anastomosed and all upper pole arteries were sacrificed. Nine arteries were identified before surgery (five were to the lower pole), and nine were missed (four to the lower pole). There were 13 kidneys with more than one vein. Four of these were seen on MRI. However, an extra vein was anastomosed in only one case. On review of the imaging, three arteries were missed because of human error and six due to technical limitations. Of the nine missed veins, only three were easily identified retrospectively. Overall, using MRI as a preoperative investigation for the 111 consecutive cases, the surgeon encountered a previously unidentified accessory artery in nine (8%), and this required anastomosis in four (4%). CONCLUSION: MR angiography has the advantage over computed tomography (CT) of having virtually no side-effects, and if the small possibility is accepted of missing extra vessels because of technical limitation or interpretation, it is a good investigation. However, in light of the failure to visualize all arteries transplanted, we have started to use multi-slice (16-channel) CT to see if its improved spatial resolution alters the results.     

Multidetector computed tomography vs magnetic resonance imaging for defining the upper limit of tumour thrombus in renal cell carcinoma: a study and review

OBJECTIVE: To compare the findings of multidetector computed tomography (CT) with surgical pathology and magnetic resonance imaging (MRI), to determine the accuracy of delineating the superior extent of inferior vena cava (IVC) thrombotic involvement in renal cell cancer (RCC). PATIENTS AND METHODS: A prospective database was examined of 11 patients (median age 65 years, range 45-77) being assessed for suspected IVC extension of RCC tumour thrombus with both multidetector CT and MRI. All had pathology confirming RCC, and eight of those undergoing surgery had pathological confirmation of tumour thrombus extent. All images were analysed originally, then re-analysed by two independent radiologists, an experienced urologist and a urological trainee unaware of the original reports and other imaging results, with a final determination on tumour thrombus level by consensus. RESULTS: The multidetector CT results were completely accurate when compared with surgical specimens and were in agreement with MRI on all but one occasion, where MRI determined the renal vein to be clear when it was involved on CT and at surgery, giving MRI an accuracy of seven of eight samples. CONCLUSIONS: Whilst there were few patients and further studies are needed, multidetector CT was comparable with MRI in determining tumour thrombus level. More importantly, in the eight patients with surgical pathological confirmation, multidetector CT was accurate in all. Ultimately, it may replace MRI as the 'gold standard' for imaging to delineate the upper limit of tumour thrombosis in RCC.     

Economic and ethical impact of extrarenal findings on potential living kidney donor assessment with computed tomography angiography

To determine the prevalence and spectrum of extrarenal findings in a screening population of potential living kidney donors undergoing renal Computed tomography angiography (CTA) and evaluate their impact on subsequent patient management and imaging costs. Two radiologists retrospectively reviewed 175 consecutive renal CTA's performed for assessment of potential living kidney donors. Extrarenal radiological findings were recorded and classified according to high, medium, or low importance based on clinical relevance and the need for further investigations and/or treatment. The cost of additional imaging examinations was calculated using 2002 Canadian (British Columbia) reimbursements. There were 73 extrarenal findings in 71/175 (40.6%) of the potential kidney donors in the study population. Findings were categorized as of high clinical importance in 18 (10.3%) cases, including lung lesions, bowel tumors, and liver tumors and as medium importance in 31 (17.7%). Twenty-two (12.6%) individuals had findings categorized as low importance, probably of no clinical significance and requiring no follow-up. Further potential evaluation of the 49 patients (28%) with highly and moderately significant extrarenal findings may require an additional $6137 (mean $35.1 per each case of all the screened patients). Transplantation of a kidney from a living donor is an excellent alternative to cadaveric allografts. Potential living kidney donors are a highly selected population of healthy individuals, screened for significant past or current medical conditions before undergoing CTA. Despite this screening, potentially significant extrarenal findings (classified as high or medium importance) were revealed in 28% of patients. These patients may require further investigations and/or treatment. The referring physician and patient should be aware of such potentially high probability, which may require further nontransplant related evaluation and treatment. This has medical, legal, economic, and ethical implications.     

Utility of CT angiography for evaluation of living kidney donors

We reviewed our initial experience with helical computed tomography (CT) angiography in the evaluation of living kidney donors which, until now, has necessitated arteriography. Nineteen donors (12 women, 7 men) have had their renal anatomy evaluated solely by CT angiography preoperatively.All scans demonstrated normal collecting systems and single ureters. Five donors (26%) had supernumerary renal arteries. Fourteen donors had single, 4 donors had two, and 1 donor had three renal arteries. Helical CT demonstrated small polar vessels in several donors. Two donors (10%) had supernumerary renal veins. Accuracy of vascular anatomy defined on CT was 90% when confirmed at operation. Anatomically all CT findings were consistent with operative findings except in 1 donor who was found to have a 0.8 cm lesion near the renal hilum.At our institution, the total charges for selective renal arteriography are $3845 and for helical CT with three-dimensional (3-D) reconstruction are $1546. The amount of contrast dye (approximately 100 mL) is equivalent. Patients uniformly reported that the CT scan was a convenient and painless procedure.The accuracy of helical CT angiography is equivalent to arteriography in assessing renal vascular anatomy (with the additional benefit of imaging venous and parenchymal anatomy). Charges for helical CT are 59% less. There is greater patient acceptance and potentially less morbidity associated with the non-invasive nature of helical CT. We believe that CT angiography is the radiologic procedure of choice for the assessment of renal anatomy in potential living kidney donors.     

Assessment of live kidney donors by magnetic resonance angiography: reliability and impact on outcomes

Abstract: Background:  Kidney allograft retrieval from live donors requires accurate determination of kidney anatomy prior to surgery, particularly the arterial supply. Traditionally, conventional angiography has been used to obtain this information. Magnetic resonance angiography (MRA) offers a non-invasive, cost-effective alternative, but has been considered to be less accurate. Despite this criticism, many centers have moved to MRA screening of potential kidney donors. The objective of this study is to evaluate our experience of the reliability of MRA in determining the arterial anatomy of living kidney donors as compared to the intra-operative findings.
Methods:  We performed a retrospective review of gadolinium-enhanced, ultra-fast, three-dimensional, spoiled gradient-echo MRA in live kidney donors in the Southern Alberta Transplant Program and compared these results with the intra-operative findings during nephrectomy, as the gold standard.
Results:  Of the 66 patients, an accessory renal artery was found intra-operatively in eight cases; two of which were erroneously diagnosed as normal by MRA. The negative predictive value for MRA was 0.97, false-negative rate was 0.25, and sensitivity was 0.75. No patient experienced side-effects from the MRA procedure. No donor needed conversion to open nephrectomy because of an undetected accessory renal artery. One allograft with an accessory renal artery developed thrombosis of the lower pole of the kidney despite arterial reconstruction. Kidney function in the recipient of this allograft was excellent and there was no urinary leak.
Conclusion:  In our hands, MRA determined the vascular anatomy of potential kidney donors with an acceptable negative predictive value of 97%.     

Multidetector CT angiography in living donor renal transplantation: accuracy and discrepancies in right venous anatomy

Kulkarni S, Emre S, Arvelakis A, Asch W, Bia M, Formica R, Israel G. Multidetector CT angiography in living donor renal transplantation: accuracy and discrepancies in right venous anatomy.
Clin Transplant 2011: 25: 77–82. © 2010 John Wiley & Sons A/S. Abstract: Multidetector computed tomography (MDCT) angiography is a reliable technique for assessing pre‐operative renal anatomy in living kidney donors. The method has largely evolved into protocols that eliminate dedicated venous phase and instead utilize a combined arterial/venous phase to delineate arterial and venous anatomy simultaneously. Despite adoption of this protocol, there has been no study to assess its accuracy. To assess whether or not MDCT angiography compares favorably to intra‐operative findings, 102 donors underwent MDCT angiography without a dedicated venous phase with surgical interpretation of renal anatomy. Anatomical variants included multiple arteries (12%), multiple veins (7%), early arterial bifurcation (13%), late venous confluence (5%), circumaortic renal veins (5%), retroaortic vein (1%), and ureteral duplication (2%). The sensitivity and specificity of multiple arterial anomalies were 100% and 97%, respectively. The sensitivity and specificity of multiple venous anomalies were 92% and 98%, respectively. The most common discrepancy was noted exclusively in the interpretation of right venous anatomy as it pertained to the renal vein/vena cava confluence (3%). MDCT angiography using a combined arterial/venous contrast‐enhanced phase provides suitable depiction of renal donor anatomy. Careful consideration should be given when planning a right donor nephrectomy whether the radiographic interpretation is suggestive of a late confluence.     

Risks and complications in 160 living kidney donors who underwent nephroureterectomy.

BACKGROUND: The rate of living donor renal transplantations has increased. However, in view of the possible complications, the question as to whether the condition of the recipient justifies operation of the donor still remains unanswered. The present retrospective study evaluates the perioperative and post-operative risks and complications for the donor at a single major transplantation centre. METHODS: From 1994 to 2001, 160 live donor nephroureterectomies were performed. The median age of living donors was 51 years (range 21-77 years); 19 patients were older than 61 years. After confirming blood group compatibility and negative cross-match, donors underwent an extensive medical and psychological examination. Comorbidities and anatomical features of the donor were evaluated and the impact they may have on the outcome was determined. The nephroureterectomies were performed transperitoneally, with the right kidney being preferred. Pre-operative, intraoperative and post-operative complications were documented. Serum creatinine levels as well as new-onset proteinuria or hypertension were used as criteria for assessing long-term renal function. RESULTS: Complications were observed in 41 donors: 35 were minor and six were major (splenectomy; revisions due to liver bleeding, incarcerated umbilical hernia or infected pancreatic pseudocyst; pneumothorax; and acute renal failure). No patient died. Multiple arteries (14 patients), significant renal artery stenosis (two patients) and additional risk factors (e.g. increased age and previous operations) did not affect the complication rate. In the post-operative follow-up period of 0.5-62 months (mean: 38 months), renal function remained stable in all donors. CONCLUSIONS: Living donor nephrectomy appears to be a safe intervention in specialized centres, where it entails a low morbidity for the donor. Even in high-risk donors, long-term complications were not observed.     

"All-in-one" imaging protocols for the evaluation of potential living liver donors: comparison of magnetic resonance imaging and multidetector computed tomography.

In order to compare the performance of "all-in-one" magnetic resonance imaging (MRI) and "all-in-one" multidetector computed tomography (MDCT) in the preharvest evaluation 25 potential living donors underwent both MRI and MDCT. MRI was performed on a high-performance 1.5-T scanner, computed tomography (CT) on a 4-row multidetector-scanner. Both scan protocols included angiography of the arterial and venous hepatic systems. CT additionally included infusion of a biliary contrast agent. Data analysis was performed by 4 reviewers, based on source images, multiplanar reformats, and three-dimensional (3D) postprocessing. Determination of image quality was based on a 4-point image quality rating (IQR) scale, ranging from 1 = nondiagnostic to 4 = excellent. Preoperative and intraoperative (n = 13) findings were correlated. Magnetic resonance (MR) examinations were generally well tolerated. Within the CT scan, 2 candidates presented moderate adverse reaction to the biliary contrast agent. MRI and CT showed the same benign parenchymal lesions (IQR MR: 3.7; IQR CT: 3.4). Determination of liver volumes was easier based on CT (IQR MR: 3.3; IQR CT: 3.6). Magnetic resonance angiography (MRA) revealed 10 variants of the arterial liver supply (IQR: 3.0) and computed tomographic angiography (CTA) revealed 13 variants (IQR: 3.5). Magnetic resonance cholangiopancreatography (MRCP) identified 4 biliary variants (IQR: 1.3) and CT cholangiography identified 17 (IQR: 3.5). MRI and CT each showed 4 hepatic and portal venous variants (IQR MR: 3.4, CT: 2.8). CT and MR findings correlated well with intraoperative findings. In conclusion, both techniques proved to be efficient to evaluate potential living liver donors' anatomy in a single diagnostic step. The main advantage of CT lies in the ability to accurately assess the biliary anatomy.     

Evaluation of the vascular anatomy in potential living kidney donors with gadolinium‐enhanced magnetic resonance angiography: comparison with digital subtraction angiography and intraoperative findings

Asgari MA, Dadkhah F, Ghadian AR, Razzaghi MR, Noorbala MH, Amini E. Evaluation of the vascular anatomy in potential living kidney donors with gadolinium‐enhanced magnetic resonance angiography: comparison with digital subtraction angiography and intraoperative findings.
Clin Transplant 2011: 25: 481–485. © 2010 John Wiley & Sons A/S. Abstract: Background: X‐ray contrast arteriography has traditionally been used for pre‐operative evaluation in living kidney donors. However, magnetic resonance angiography (MRA) offers a non‐invasive alternative, which has been considered to be less accurate. This study was performed to determine whether MRA in the pre‐operative investigation of living kidney donors provides sufficient information. Methods: From December 2005 to December 2007, 173 potential live donors were evaluated in this study. Donors performed digital subtraction angiography (DSA) and those with one or more accessory arteries at least on one side recruited for further evaluation with three‐dimensional gadolinium‐enhanced MRA. Results: A total of 30 donors constituted the study population. When compared with DSA as the reference method, MRA detected 20 of 36 renal accessory arteries which indicates a sensitivity of 55.6%. The difference between MRA and DSA in identifying accessory renal arteries was significant (p‐value <0.001). Considering intraoperative findings as the standard of reference, MRA depicted correctly four of six (66.7%) accessory arteries on the transplanted kidneys. Conclusions: MRA has the advantage of avoiding exposure to ionizing radiation and is non‐invasive. These are important considerations in pre‐operative evaluation of a generally healthy donor population. However, MRA provides suboptimal accuracy in detecting small accessory arteries.     

Multilocular cystic renal cell carcinoma: clinicopathological features and preoperative prediction using multiphase computed tomography

Study Type – Diagnostic (exploratory cohort) Level of Evidence 2b What’s known on the subject? and What does the study add? Multilocular cystic renal cell carcinoma (MCRCC), defined according to the 2004 WHO classification, has good prognosis, which is not affected adversely by large tumour size or advanced stage. Thus nephron‐sparing surgery is proposed when MCRCC is suspected by preoperative radiologic criteria. The present study confirms the low malignant potential of MCRCC. Additionally, the results of the present study provide a simple, useful criteria using a Bosniak classification and Hounsfield unit on multiphase computed tomography images to differentiate MCRCC from other cystic RCC.

OBJECTIVE

? To analyse the clinicopathological and radiological features of multilocular cystic renal cell carcinoma (MCRCC) and to determine the preoperative factors differentiating MCRCC from other cystic RCC (CRCC).

PATIENTS AND METHODS

? The medical records of 53 patients with complex cystic renal masses evaluated by multiphase computed tomography (CT), surgically removed and confirmed as sporadic RCC were reviewed. ? Of these 53 patients, 23 were classified as having MCRCC and 30 as other CRCCs, defined as RCCs with extensive cystic change or cystic necrosis. ? Another 22 patients were treated for complex cystic renal masses presumed to be RCC and diagnosed as having benign cyst.

RESULTS

? Benign cysts and MCRCCs were significantly more likely to be of Bosniak classification III than other CRCCs (77% vs 61% vs 27%, P= 0.001). ? The mean Hounsfield unit (HU) during the corticomedullary phase (CMP) was significantly higher in other CRCCs, with HU ≥38 having 83% sensitivity and 80% specificity for predicting other CRCCs. ? In a multiple regression model, Bosniak classification and mean HU during CMP were independent factors predictive of other CRCCs. ? In the 41 patients with masses >4 cm in diameter, the combination of Bosniak classification IV and HU ≥38 during CMP showed 63% sensitivity, 96% specificity, 91% positive predictive value and 80% negative predictive value, yielding 2% false‐positive and 15% false‐negative rates.

CONCLUSIONS

? The mean HU during CMP and Bosniak classification can differentiate MCRCC from other CRCCs. ? This could help in selecting an appropriate surgical method, such as nephron‐sparing surgery, for complex cystic renal masses >4 cm.     

Preoperative evaluation of biliary anatomy of donor in living donor liver transplantation by conventional nonenhanced magnetic resonance cholangiography

Detailed preoperative evaluation of the biliary anatomy of the donor in living donor liver transplantation (LDLT) can minimize postoperative morbidity in the recipient and maximize safety for the donor. We prospectively evaluated the diagnostic accuracy and clinical usefulness of nonenhanced conventional magnetic resonance cholangiography (MRC) for depicting the biliary anatomy of LDLT donors. MRC and intraoperative cholangiography (IOC) examinations of 111 donors were performed between August 2005 and February 2006. We observed the classical branching pattern of the biliary system in 67 subjects (60.4%), with the remaining 44 subjects (39.6%) showing anatomical variations. MRC showed accurate anatomy of the biliary system, using IOC as the reference standard, in 98 (88.3%) subjects. MRC had a sensitivity in differentiating normal from variant anatomy of 95.5%, specificity of 95.2%, a positive predictive value of 96.8% and a negative predictive value of 93.3%. The agreement between MRC and IOC findings, as evaluated by kappa-value (0.865) was statistically significant (P<0.001). In conclusion, the diagnostic accuracy of conventional nonenhanced MRC is sufficient for this method to be used for the preoperative evaluation of biliary anatomy in LDLT donor candidates.     

CT volumetry is superior to nuclear renography for prediction of residual kidney function in living donors

Living kidney donor evaluation commonly includes nuclear renography to assess split kidney function and computed tomography (CT) scan to evaluate anatomy. To streamline donor workup and minimize exposure to radioisotopes, we sought to assess the feasibility of using proportional kidney volume from CT volumetry in lieu of nuclear renography. We examined the correlation between techniques and assessed their ability to predict residual postoperative kidney function following live donor nephrectomy. In a cohort of 224 live kidney donors, we compared proportional kidney volume derived by CT volumetry with split kidney function derived from nuclear renography and found only modest correlation (left kidney R²=26.2%, right kidney R²=26.7%). In a subset of 88 live kidney donors with serum creatinine measured 6 months postoperatively, we compared observed estimated glomerular filtration rate (eGFR) at 6 months with predicted eGFR from preoperative imaging. Compared to nuclear renography, CT volumetry more closely approximated actual observed postoperative eGFR for Chronic Kidney Disease Epidemiology Collaboration (J‐test: P=.02, Cox–Pesaran test: P=.01) and Mayo formulas (J‐test: P=.004, Cox–Pesaran test: P<.001). These observations support the use of CT volumetry for estimation of split kidney function in healthy individuals with normal kidney function and morphology.     

Imaging characteristics of papillary renal cell carcinoma by computed tomography scan and magnetic resonance imaging

AIM: To analyse the differences in the patterns between clear and papillary renal cell carcinomas using magnetic resonance imaging (MRI) and dual-phase helical computed tomography (CT). METHODS: We examined seven patients with papillary renal cell carcinoma, and six with clear cell carcinoma. The highest attenuation value of tumors in the corticomedullary phase (CMP) and the excretory phase (EP) was measured using the observer-defined region of interest (ROI). MRI consisted of T1-weighted and T2-weighted spin-echo imaging. RESULTS: All five tumors except for one with papillary renal cell carcinoma showed homogenous hypointensity, but all six tumors with clear cell carcinoma showed heterogeneous hyperintensity on their T2-weighted images. In the CMP, the mean CT numbers of the papillary renal cell carcinomas were significantly lower than those of the clear cell carcinomas. The mean enhancement of the papillary renal cell carcinomas in the CMP and the EP was significantly lower than that of the clear renal cell carcinomas. The mean CT numbers of the clear cell carcinomas in the CMP were markedly increased from those on the unenhanced CT; those in the EP were decreased gradually. But the mean CT numbers of the papillary renal cell carcinomas in the EP were still slightly more increased than those in the CMP. The enhancement patterns of the papillary renal cell carcinomas in the CMP and the EP were homogenous, but those of the clear cell carcinomas were heterogeneous. CONCLUSIONS: We can speculate the differential diagnosis from clear to papillary renal cell carcinoma using MRI and dual-phase helical CT.