CT angiography of potential renal transplant donors

Renal transplantation has grown rapidly over the past 30 years, resulting in an inadequate supply of organs to meet the ever-increasing demand. This has led to an increase in the number of living-related donors. Advances in imaging technology now allow safe, rapid, and relatively noninvasive evaluation of potential donors. Helical computed tomographic (CT) angiography is a fast, minimally invasive procedure that is quickly becoming the imaging modality of choice for preoperative evaluation of potential renal transplant donors. Helical CT, combined with low-osmolar intravenous contrast materials, has enabled CT angiography to depict arterial and venous anatomy accurately. Between July 1995 and March 1997, CT angiography was performed in 205 potential renal donors. Correlation with surgical findings in 136 donor nephrectomies helped confirm a high level of accuracy for CT angiography in the assessment of the renal vasculature: Sensitivity and specificity for identifying specific vessels was 99.6% and 99.6% for main renal arteries, 76.9% and 89.9% for polar arteries, and 98.7% and 95.5% for main renal veins, respectively. CT angiography allows the radiologist to provide the transplant surgeon with precise preoperative anatomy of the renal vasculature, thus reducing the risks and complications associated with the harvesting procedure and improving the chances for a successful outcome. However, accurate radiologic interpretation depends on the radiologist's experience level, attention to detail, and commitment to careful image evaluation.     

N-methyl-D-aspartate receptor blockade attenuates D1 dopamine receptor modulation of neuronal activity in rat substantia nigra

Recent technical advances in CT have renewed interest in the development of CT angiography (CTA). CT angiography is a minimally invasive method of visualising the vascular system and is becoming an alternative to conventional arteriography in some situations. Spiral technology allows a volume of data to be obtained on a single breath-hold with no respiratory misregistration. Fast machines with second or subsecond acquisition times mean the images are obtained while there are high circulating levels of contrast medium giving peak vascular opacification from a peripheral intravenous injection. Accurate timing will ensure either the arterial or venous phase is imaged. Multiple overlapping axial images can be obtained from the data set with no increase in radiation dose to the patient and from these scans computer generated multiplanar and 3D images are obtained which can be viewed from numerous angles. CT angiography can be performed more quickly, less invasively and at reduced cost compared to conventional angiography.     

Attitudes of Mexican geneticists towards prenatal diagnosis and selective abortion

OBJECTIVE: To assess donor morbidity, recipient outcome, and changing trends during the past decade in donor nephrectomy for living-donor kidney transplantation. DESIGN AND SETTING: Retrospective review at an academic tertiary care referral center. PATIENTS: We reviewed 201 consecutive living-donor kidney transplantations performed between January 1988 and June 1997. INTERVENTION: Donor nephrectomy and living-donor kidney transplantation. MAIN OUTCOME MEASURES: Donor surgical complications, correlation of preoperative imaging of donor vascular anatomy and operative findings, and donor lengths of stay in the hospital were analyzed. Recipient delayed graft function and actuarial 1- and 5-year patient and graft survival rates were also analyzed. RESULTS: Major donor postoperative complications were bleeding (0.5%), pneumothorax requiring a chest tube (1%), wound infection (1%), and pneumonia (1%). Minor postoperative complications were asymptomatic pneumothorax resolving spontaneously (10%), urinary retention (6%), and urinary tract infection (0.5%). Preoperative imaging failed to detect small accessory renal arteries in 12% of donors. The mean donor length of stay in the hospital was 5.0 days but decreased from 6.2 to 4.0 days during the study. Twenty donors (10%) were unrelated (ie, spouse or friend). Three (1.5%) cases of delayed graft function occurred. Overall recipient patient survival at 1 and 5 years was 97% and 90%, and graft survival was 95% and 83%, with no difference between related and unrelated living donors. CONCLUSIONS: Living-donor nephrectomy is associated with low surgical morbidity. Recent trends include shortened lengths of stay in the hospital, the use of computed tomographic angiography instead of digital subtraction angiography for preoperative imaging of donor vascular anatomy, and an expanded use of unrelated living donors.     

Head and neck vascular anatomy

Conventional computed tomography (CT) and magnetic resonance (MR) angiography provide excellent vascular images; however, every radiologist interpreting routine cross-sectional imaging of the head and neck must recognize normal and abnormal vascular structures. Knowledge of the normal cross-sectional appearance of vessels can help to define spacial anatomy and provide for recognition of abnormal vessels. Intracranially, the major arterial branches of the Circle of Willis are routinely visualized on MR and CT, as are the dural venous sinuses and major tributaries to the deep and superficial venous system. Using a combination of CT and MR images, we demonstrate the normal cross-sectional vascular anatomy of the head and neck and the important anatomic relationships key to accurate imaging analysis.     

Evaluation and management of solid and cystic renal masses

PURPOSE: With the increasing detection of incidental renal lesions, the evaluation and management of solid and cystic renal masses are assuming greater importance in urological practice. A review of the techniques for evaluation and management is presented, with an emphasis on new and evolving procedures, along with recommendations for their selective use. MATERIAL AND METHODS: A MEDLINE computerized reference search and manual bibliographic review were performed to find pertinent peer reviewed articles published since 1985. Meeting abstracts were considered if they provided unique information. RESULTS: The primary means of evaluating renal masses is radiography (mainly ultrasonography and computerized tomography), although minimally invasive techniques such as percutaneous biopsy and laparoscopy are useful in selected situations. Nephron sparing surgery, minimally invasive surgery, alternative energy sources and other new techniques are being increasingly applied to the management of solid and cystic renal masses. CONCLUSIONS: Simple renal cysts can be defined ultrasonographically but more complicated masses require computerized tomography, other imaging modalities or rarely biopsy. Currently, minimally invasive techniques are commonly applied only to assist in the diagnosis of selected renal lesions and to treat benign simple cysts. The treatment of choice of solid renal masses remains open surgical radical nephrectomy and partial nephrectomy but alternative techniques will likely have a more significant role in the near future.     

Molecular analysis of the malR gene of Clostridium butyricum NCIMB 7423, a member of the LacI-GalR family of repressor proteins

OBJECTIVE: The purpose of our study was to evaluate helical CT using axial, coronal, and three-dimensional (3D) reconstruction in the examination of potential kidney donors and to compare the results with angiography and surgery when possible. We also reviewed previously published reports. SUBJECTS AND METHODS: Thirty-six patients underwent unenhanced and enhanced helical CT (3-mm collimation, 150-170 ml of i.v. contrast material injected at 4 ml/sec; pitch 1.5; 17-sec scan delay) with coronal and 3D shaded-surface-display reconstructions made from 1.5-mm overlapping reconstructions. All CT scans were interpreted independently of each other by two observers unaware of other findings. A third observer, who was aware of other findings, also interpreted the images. Results were compared with angiography (24 cases) and surgery (24 cases). Our results are compared with those of other investigators. RESULTS: Axial CT was the best method for detecting accessory arteries (24%) and early branching (10%); it also detected relevant venous and ureteral anatomy and incidental findings. The coronal and 3D images rarely added information that resulted in changed patient treatment. CT findings were concordant with those of digital angiography in 89% of kidneys and were 98% concordant with surgery. CONCLUSION: Helical CT can show arterial, venous, and ureteral anatomy and can also show important incidental findings. If only helical CT is used, a few small accessory vessels and an occasional renal artery stenosis may be missed. Axial images are generally diagnostic and may be supplemented by multiplanar and 3D images read concurrently.     

Intrahepatic portosystemic venous shunt: report of two cases assessed by helical computed tomography

BACKGROUND: Three-dimensional (3D) anatomic analysis was carried out, using helical computed tomography (helical CT), to evaluate its usefulness in two cases of large intrahepatic portosystemic venous shunt (IPSVS). METHODS: Case 1, a 74-year-old man with type-C hepatitis, underwent hepatic angiography to confirm suggested IPSVS of the left hepatic lobe in 1994. Case 2, a 62-year-old woman with liver cirrhosis associated with type-B hepatitis, was hospitalized for evaluation of suspected hepatocellular carcinoma in 1994. Hepatic angiography disclosed a large IPSVS in the right hepatic lobe. Retrospective evaluation of CT showed that the size of this shunt had increased over the 5 years 3D anatomic analysis was carried out, and the shunt vessels were clearly demonstrated. CONCLUSION: 3D anatomic analysis using helical CT was less invasive and useful for evaluating large IPSVS.     

Helical CT angiography for examination of living renal donors

OBJECTIVE: This prospective study was intended to determine if helical CT arteriography plus conventional radiography is sufficiently accurate to replace and less costly than excretory urography and conventional renal arteriography, the techniques currently used to examine living renal donors. SUBJECTS AND METHODS: Patients underwent CT arteriography with a helical CT scanner. Conventional radiographs were obtained during the pyelographic phase to evaluate the urothelium. Findings on CT arteriograms were compared with findings on conventional arteriograms and at surgery. RESULTS: Of 57 patients who underwent CT arteriography, 46 also underwent conventional arteriography and 40 underwent surgery. For those 46 patients, we found agreement between results of CT arteriography and conventional arteriography in 89% of kidneys. For those 40 patients, we found agreement between results of CT arteriography and findings at surgery in 90% of kidneys and agreement between results of conventional arteriography and findings at surgery in 87% of kidneys. Of the 57 patients, six (11%) had findings on CT angiograms that precluded further consideration for donation. CONCLUSION: Eight to ten percent of renal arteries are not seen on renal arteriograms when compared with findings at surgery. Our results indicate that CT arteriography is as accurate as conventional arteriography at revealing the number of vessels that perfuse and drain the kidneys and can replace conventional arteriography. Use of CT angiography plus conventional radiography instead of excretory urography and conventional arteriography can result in a 35-50% reduction in cost of the imaging studies in potential renal donors.     

Pituitary growth hormone release and gene expression in cafeteria-diet-induced obese rats

PURPOSE: To determine prospectively the feasibility and accuracy of combined gadolinium-enhanced magnetic resonance (MR) angiography, MR urography, and MR nephrography in the presurgical evaluation of potential renal transplant donors. MATERIALS AND METHODS: Twenty-two potential donors for renal transplantation were evaluated with 1.5-T MR imaging. MR angiograms were evaluated for the number of renal arteries, presence of early arterial branches, and renal artery stenoses. The renal collecting system and ureters were evaluated on the MR urograms. Renal parenchyma was assessed on the MR nephrogram. Prospective interpretation of MR images was compared with that of conventional angiograms and excretory urograms and with surgical findings. RESULTS: Gadolinium-enhanced MR angiography enabled correct identification of the arterial supply to all 44 native kidneys (44 single or dominant renal arteries and nine accessory renal arteries), four of five early arterial branches arising in the proximal 2 cm of the renal artery, a mild truncal stenosis in one renal artery, and two anomalies of the draining renal veins. The MR urogram accurately depicted a duplicated collecting system and mild unilateral pelvicalicectasis. The MR nephrogram showed renal size and a solitary cyst in one kidney, confirmed with sonography. CONCLUSION: Combined gadolinium-enhanced MR angiography, MR urography, and MR nephrography can accurately depict the arterial supply, collecting system, and renal parenchyma of donor kidneys.     

Kidney transplantation: the use of living donors with renal artery lesions

PURPOSE: A shortage of organs for transplantation has forced surgeons to optimize the use of marginal organs, such as kidneys with arterial disease. We present a retrospective study of the outcome of donors with renal artery disease and recipients of kidneys from living related and unrelated donors. MATERIALS AND METHODS: Kidneys with vascular abnormalities from healthy living donors were grafted into 11 recipients. These kidney transplants comprised 1.8% of those performed at our institution. The vascular abnormalities were aneurysms in 3 cases, atherosclerotic lesions in 4 and fibromuscular dysplasia in 4. After nephrectomy all abnormalities were corrected under hypothermic conditions during bench surgery except in 3 cases of ostial atherosclerotic plaque, which was left in the donors. The renal artery was anastomosed to the external iliac artery in 5 cases and to the internal iliac artery in 6. The ureter was reimplanted using an extravesical technique. RESULTS: All patients had immediate diuresis and no delayed post-transplant graft dysfunction was observed. One patient died of an unrelated cause and 3 had post-transplant graft function loss due to acute vasculopathy in 1, post-diarrhea with acute arterial thrombosis in 1 and recurrence of the hemolytic-uremic syndrome in 1. All remaining patients are well with median serum creatinine of 1.4 mg./dl. (normal 0.4 to 1.4). All donors are well and normotensive with normal renal function. CONCLUSIONS: The use of kidneys with arterial disease from living donors with unilateral disease is safe. Complete informed consent regarding the risks and benefits by donor and recipient is mandatory.     

Acute thrombosis in a contralateral kidney after radical nephrectomy: successful treatment by thrombolytic therapy using a tissue-type plasminogen activator

A 67-year-old male became anuric immediately after a right radical nephrectomy for renal cell carcinoma. The patient was diagnosed with an acute arterial thrombosis of the remaining kidney within 4 hours after surgery by both CT scan and angiography. Thrombolytic therapy was started by a transcatheteral infusion of tissue-type plasminogen activator (TPA) resulting in a complete recanalization. Hydration and systemic administration of heparin followed, and renal function recovered within 3 weeks. This is the first report of acute thrombosis in a contralateral renal artery immediately after a radical nephrectomy which was successfully treated with TPA. It is probable that compression of the contralateral renal artery by the retractor for an extended period of time during surgery led to this unfavorable condition.     

A 66-year-old woman with pneumonia and right heart failure

PURPOSE: The purpose of this study was to develop a shaded-surface and volume display (hybrid rendering method) of the whole vascular system of the cervico-cranial arteries using spiral computed tomography (SCT). MATERIALS AND METHODS: We examined 12 patients with anatomic abnormalities and pathological conditions of the arterial vascular system. The cervico-cranial arteries were segmented using an interactive threshold interval density volume-growing method and visualized with a color-coded shaded-surface display (SSD) rendering method. The adjacent bone structures were visualized using a transparent volume rendering method. RESULTS: In all cases, the entire volume of the vascular system of the cervico-cranial arteries and the anatomic abnormalities and pathological conditions could be visualized. CONCLUSION: Hybrid rendering of the circulation of the cervico-cranial arteries using image data sets from a subsecond spiral CT scanner is useful for the visualization of anatomical and pathological abnormalities and offer a promising minimally invasive alternative compared with other diagnostic procedures.     

Value of CT-angiography in diagnosis of cerebral sinus and venous thromboses

Dural sinus thrombosis is not uncommon. Due to the nonspecific symptomatology, as well as the manifold etiology, clinical diagnosis may be difficult. In these cases imaging procedures are frequently crucial in deciding how to proceed and how to treat. The aim of our study was to evaluate the diagnostic utility of helical CT in the detection of dural sinus thrombosis. In 20 patients with clinically suspected thrombosis CT angiography was performed. In 6 patients dural sinus thrombosis was diagnosed. In order to acquire also arterial vessels, a short delay of about 22 s after the onset of the application of contrast medium was selected. By this method we found an occlusion of the MCA in two patients with clinically suspected sinus thrombosis. In all patients the transverse slices and the multiplanar reconstructions showed filling defects or an "empty delta" sign. With irregular outlines the thrombus could be depicted over the complete course of the sinus. The MIP reconstructions were particularly helpful in the evaluation of the vessel anatomy and the pathological collateral venous drainage. In three patients MR angiograms were available for comparison. The smaller veins, such as the v. vermis inferior, were less clearly depicted than in CT angiography. CT angiography is a fast and reliable method to exclude or verify a sinus thrombosis. It can be performed immediately after non-enhanced CT. According to our present experience CT angiography is sufficient for the diagnosis of a sinus thrombosis.     

Renal vein thrombosis and constitutional protein S deficiency

Venous and arterial thrombosis due to a constitutional protein S deficiency is well-known. We report the case of a 36 year-old patient admitted to hospital in 1991 for primary renal vein thrombosis due to a constitutional protein S deficiency of type I. The diagnosis was made by CT scan and angiography. Left nephrectomy, which was made because of doubt with regard to subjacent neoplasm, showed left renal vein thrombosis and multiple renal infarcts. In 1994, after 4 months of discontinuation of oral anticoagulants, the patient presented pulmonary embolism documented by pulmonary scintigraphy and CT scan, partial portal thrombosis and sural thrombophlebitis documented by echography coupled with Doppler. To our knowledge, this is the first reported case of a constitutional protein S deficiency associated with primary renal vein thrombosis.     

Contrast-enhanced, K-space-centered, breath-hold MR angiography of the renal arteries and the abdominal aorta

The purpose of this study was to evaluate the capability of contrast-enhanced breath-hold fast imaging with steady-state precession (FISP) three-dimensional MR angiography (MRA) to detect stenotic lesions of the abdominal aorta, the renal arteries, and the iliac arteries by using a K-space-centered 20-ml gadolinium-diethylene pentaacetic acid (Gd-DTPA) bolus. Fifty patients were studied before conventional x-ray angiography. Contrast-enhanced breath-hold FISP three-dimensional MRA was applied in the coronal view, centered at the renal arteries. Twenty ml of Gd-DTPA was used in all subjects. A test bolus was applied to determine the injection time for the K-space-centered bolus injection. Of 300 segments, 284 segments were classified correctly, 11 were overestimated, and five were underestimated. Sensitivity was 98%, specificity was 96%, positive predictive value was 96%, negative predictive value was 98%, and accuracy was 97%. Of the 50 patients studied, 43 were staged correctly. No venous overlay was seen in 31 patients; partial overlay was seen in 16 patients, and venous structure overlay obscuring arterial anatomy was found in two patients. Six of nine accessory renal arteries could be identified by MRA. Intraobserver variability was .94. This study has shown the ability of contrast-enhanced breath-hold FISP three-dimensional MRA to detect and grade vascular lesions in the abdominal aorta and the renal arteries. The method may serve as a screening tool in the future.     

Scorpion toxins and defensins

Advances in CT, MR imaging, and catheter angiography provide the radiologist and neurosurgeon with a variety of imaging options for screening, diagnosis, presurgical evaluation, and postoperative monitoring of patients with intracranial aneurysms. Noninvasive imaging techniques have not replaced conventional angiography for the comprehensive evaluation o aneurysms but are effective in screening patients suspected to have an unruptured aneurysm or for preoperative planning in emergency situations that preclude catheter angiography. CT, CT angiography, MR imaging, and MR angiography can all complement the information obtained with catheter angiography in presurgical planning, and the choice of supplemental studies should be individualized. Rotational and intraoperative angiography are problem-solving options used for selected cases at our institution. Continuous improvements in techniques for CT and MR angiography may someday reach the point where surgery can be undertaken on the basis on noninvasive imaging alone, with catheter angiography reserved for endovascular therapy planning and guidance.     

Comparison of Doppler US and CT angiography for evaluation of renal artery stenosis

RATIONALE AND OBJECTIVES: The authors compared Doppler ultrasound (US) with computed tomographic (CT) angiography in the evaluation of stenosis of the main renal artery. MATERIALS AND METHODS: Fifty-six patients who had undergone conventional angiography of the renal arteries participated in a prospective comparison of Doppler US (45 patients) and CT angiography (52 patients). US evaluation included both the main renal artery and segmental renal arteries. RESULTS: There were 27 main renal arteries with at least 50% stenosis in 20 patients. In 36 patients, there was no significant stenosis. All cases of main renal artery stenosis detected with Doppler US of the segmental arteries were also identified with Doppler US of the main renal artery. The by-artery sensitivity (63%) of US of the main renal artery was greater than that (33%) of US of the segmental arteries. CT angiography was more sensitive (96%) than Doppler US (63%) in the detection of stenosis, but the specificity of CT (88%) was similar to that of US (89%). The difference in the area under the receiver operating characteristic curve (AUC) between CT (AUC = 0.94) and US (AUC = 0.82) was statistically significant (P = .038). CONCLUSION: Doppler US of the main renal artery is more sensitive than Doppler US of segmental arteries in the detection of stenosis. CT angiography is more accurate than Doppler US in the evaluation of renal artery stenosis.     

Renal cell carcinoma in a horseshoe kidney: report of two cases

We report 2 patients with renal cell carcinoma in a horseshoe kidney. A renal tumor was diagnosed during evaluation of right humeral metastatic cancer of unknown origin in case 1 (64-year-old male) and gross hematuria in case 2 (54-year-old male). Both patients underwent radical nephrectomy with division of isthmus and retroperitoneal lymph node dissection. The tumors were staged pathologically as pT2bpN0pV0pM1(oss) and pT3pN0pV1bM0, respectively. Only 27 cases of renal cell carcinoma developed in a horseshoe kidney, including the present two cases, have been reported in the Japanese literature. The blood supply to the horseshoe kidney and its evaluation by preoperative angiography were discussed.     

CO2 and gadopentetate dimeglumine as alternative contrast agents for malfunctioning dialysis grafts and fistulas

BACKGROUND: Hemodialysis grafts and native fistulas are frequently evaluated angiographically utilizing iodinated contrast material to determine the cause of malfunction. Occasionally, patients are not able to receive iodinated contrast material due to a history of previous severe allergic reaction or concern that iodinated contrast material could worsen renal function requiring premature initiation of permanent dialysis. We set out to test the feasibility of gadopentetate dimeglumine as an alternative contrast agent in conjunction with carbon dioxide (CO2) angiography in the evaluation and treatment of hemodialysis grafts and native fistulas in patients who have a contraindication to iodinated contrast material. METHODS: Six patients with a malfunctioning hemodialysis graft and native fistula were evaluated. Four patients were successfully evaluated using carbon dioxide and gadopentetate dimeglumine. Two additional patients underwent balloon angioplasty using gadopentetate dimeglumine alone as the alternative contrast agent. RESULTS: All six patients successfully were evaluated and treated using gadopentetate dimeglumine either alone or as a supplement to CO2 angiography. Five of these patients had lesions successfully treated using gadopentetate dimeglumine alone or in combination with CO2 as the angiographic contrast agents. One patient underwent a successful diagnostic angiogram using gadopentetate dimeglumine and CO2 as alternative contrast agents and was subsequently treated with surgical revision. The gadopentetate dimeglumine angiograms identified the arterial anastomosis and more clearly identified stenotic lesions and venous outflow anatomy compared to carbon dioxide angiograms. CONCLUSION: Gadopentetate dimeglumine is useful as an alternative contrast agent in conjunction with CO2 in patients with malfunctioning hemodialysis grafts and fistulas, who have a contraindication to the administration of iodinated contrast material.     

The limited value of preoperative angiography in microsurgical reconstruction of the lower limb

Biplanar angiography has been a prerequisite in microvascular reconstruction of the lower extremity. While defining arterial anatomy, the procedure is not without morbidity. More important, angiography does not determine the acceptability of arterial blood flow through a particular recipient vessel. The purpose of this study was to evaluate the safety of microvascular tissue transplantation for reconstruction of complex lower-limb wounds, without preoperative angiography. A consecutive series of 48 patients undergoing tissue transplantation for complex wound reconstruction during a recent 8-month period is presented. Sixty percent of patients had soft-tissue wounds classified as Gustilo IIIB preoperatively, although 89 percent of wounds ultimately arose from trauma. Preoperative and intraoperative clinical assessment of recipient vessels allowed successful reconstruction in all but one case. The only loss of a transplant arose as a result of venous outflow obstruction, a situation not to be improved by preoperative angiography. In no instance was a patient explored and reconstruction deferred due to inadequate recipient vasculature. The results of this study support microvascular tissue transplantation to lower-limb wounds without preparatory angiography in almost all circumstances. Adequate clinical parameters are presented for determining recipient pedicle status, both preoperatively and intraoperatively.