Aneurysms of the supra-aortic trunks in Takayasu's disease. Report of two cases

Takayasu's arteritis is a chronic inflammatory disease of unknown etiology, which affects the aorta and its branches. The resulting lesions can be of steno-occlusive or aneurysmatic type; the latter form is relatively rare. The authors report 2 cases which came under their observation for treatment. The first was a young man of 22 years with aneurysm of the common right carotid artery and of the subclavian left intrathoracic artery. The carotid aneurysm was operated first; arterial reconstruction was ensured by means of a dacron bypass as the saphenous vein was not usable. Three months later, exeresis of the subclavian aneurysm was performed with a left thoracotomy in the IV space. The postoperative course was uneventful and no untoward event has been observed during follow-up (15 months). The second case was a young girl of 16 years with poststenotic aneurysmatic dilatation of the anonyma artery, tight stenosis of the left renal artery and occlusion of the right renal artery. The patient underwent median sternotomy and removal of the aneurysmatic wall together with the stenosis, and a dacron patch was applied. During preoperative angiography, the stenosis of the left renal artery had been treated with PTA; one month after the first operation, a right aorto-renal bypass was fashioned with the saphenous vein. Postoperative stay was free from complications on both occasions and complete normalization of the pressure values was obtained, which persists after 12 months.

[Three patients with a kidney infarct]

Two patients, one 76-year-old-man and one 79-year-old-woman with cardiovascular disease and one 36-year-old-man with Factor-V-Leiden deficiency (activated protein C-resistance) had abdominal pain and elevation of LDH levels. With abdominal CT scan kidney infarction was diagnosed. In two cases a selective kidney arteriography was performed to confirm the diagnosis. Treatment consisted of (re)starting anticoagulant therapy. In unexplained abdominal pain with insufficiently specific results of physical examination combined with a rapid rise of the LDH and sometimes of the serum creatinine, a kidney infarction should be considered in the differential diagnosis.

Abciximab combined with angioplasty in a patient with renal artery stent subacute thrombosis

Following renal artery angioplasty and stenting, a female hypertensive patient suffered left renal artery stent subacute thrombosis. A second successful angioplasty was performed using 5000 U heparin i.v. and 0.25-mg/kg bolus followed by a 12-hr 10-microg/min infusion of abciximab. Normal renal flow was re-established and remained normal at 1-year follow-up.

Ischemic nephropathy: diagnosis and treatment

Recent epidemiologic studies have shown that ischemic nephropathy secondary to stenosis or obstruction of the main renal arteries in the cause of renal insufficiency in a growing number of subjects. The clinicians dealing with renovascular disease need non-invasive diagnostic tools and effective therapeutic measures to successfully face the problem. Duplex ultrasound scanning is a non-invasive, non expensive diagnostic tool and when an experienced, dedicated technologist is available, it should be suggested as the first-step test. Magnetic resonance angiography and spiral CT angiography play an ancillary role in detecting patients with renovascular disease. Captopril-enhanced (CE) scintigraphy when positive indicates the activation of intrarenal renin-angiotensin system and may be useful in detecting patients with renal artery stenosis. Moreover, CE scintigraphy can play an important role in the choice between the revascularization and a wait-and-see approach. As a matter of fact, the presence of an activated intrarenal renin-angiotensin system furnishes theoretical as well practical reasons in favour of the revascularization. In the recent years percutaneous transluminal renal angioplasty has become the cornerstone of therapeutic strategy. The introduction of the metallic stent has dramatically improved its efficacy in ostial stenoses and has reduced the indication for surgical revascularization.

A clinical prediction rule for renal artery stenosis

BACKGROUND

Renal artery stenosis is a rare cause of hypertension. The gold standard for diagnosing renal artery stenosis, renal angiography, is invasive and costly.

OBJECTIVE

To develop a prediction rule for renal artery stenosis from clinical characteristics that can be used to select patients for renal angiography.

DESIGN

Logistic regression analysis of data from a prospective cohort of patients suspected of having renal artery stenosis. A prediction rule was derived from the regression model for use in clinical practice.

SETTING

26 hypertension clinics in The Netherlands.

PATIENTS

477 hypertensive patients who underwent renal angiography because they had drug-resistant hypertension or an increase in serum creatinine concentration during therapy with angiotensin-converting enzyme inhibitors.

RESULTS

Age, sex, atherosclerotic vascular disease, recent onset of hypertension, smoking history, body mass index, presence of an abdominal bruit, serum creatinine concentration, and serum cholesterol level were selected as predictors. The regression model was reliable (goodness-of-fit test, P > 0.2) and discriminated well between patients with stenosis and those with essential hypertension (area under the receiver-operating characteristic curve, 0.84). The diagnostic accuracy of the regression model was similar to that of renal scintigraphy, which had a sensitivity of 72% and a specificity of 90%.

CONCLUSIONS

In the diagnostic workup of patients suspected of having renal artery stenosis, the clinical prediction rule can be considered as an alternative to renal scintigraphy. It can help to select patients for renal angiography in an efficient manner by reducing the number of angiographic procedures without the risk for missing many renal artery stenoses.

Gd-enhanced 3D phase-contrast MR angiography and dynamic perfusion imaging in the diagnosis of renal artery stenosis

The objective of this study was to investigate the role of contrast enhancement using a three-dimensional (3D) phase-contrast (PC) magnetic resonance (MR) sequence (3D PC-MRA) and to assess the value of a dynamic MR perfusion study of the kidneys to determine the hemodynamic relevance of unilateral renal artery stenosis (RAS). Seventeen patients with unilateral RAS were examined on a standard 1.0 T imaging system using a phase shift and magnitude sensitive 3D PC sequence (TR=160 ms, TE=9 ms, venc. 30 cm/s). Following the initial pre-contrast 3D PC-MRA a dynamic first pass perfusion study was performed using a Turbo-FLASH 2D sequence (TR=4.5 ms, TE=2.2 ms, TI=400 ms) after bolus injection of 0.15 mmol gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)/kg body weight. The 3D PC-MRA was then repeated during infusion of 0.15 mmol Gd-DTPA/kg body weight. Evaluation by three independent readers was based on maximum intensity projection images. Source images were rendered on request. Signal intensity (SI) over time curves of the renal cortex were obtained from the dynamic perfusion study and analyzed for maximum signal enhancement as well as temporal relationship to the aortic SI curve. Results from 3D PC-MRA revealed a sensitivity (pre-/post-contrast) of 100%/89%, specificity of 76%/63%, positive predictive value of 80%/69 %, negative predictive value of 90%/78%, and accuracy of 85%/75% (p=0.07). Interobserver agreement was kappa=0.61/kappa=0.47 (pre/post Gd-DTPA), respectively. Increased signal-to-noise was present in all segments of the renal arteries post contrast (p=0.0003). This came along with image degradation due to aliasing and elevated SI of venous flow that partially obscured the renal arteries. Dynamic SI curves showed a significantly decreased maximum SI in RAS (p=0.01-0.001). A temporal delay of cortical signal intensity enhancement could not be confirmed in this setting. Gd-enhanced 3D PC-MRA did not yield a superior diagnostic value in the diagnosis of RAS compared to pre-contrast measurements. Dynamic perfusion imaging of the kidneys, in combination with 3D PC-MRA, can contribute additional information in suspected unilateral RAS.

Screening for renovascular hypertension in a population with relatively low prevalence

OBJECTIVE

To evaluate the accuracy and cost-efficacy of the diagnostic procedure and treatment for renovascular hypertension.

SETTING AND PATIENTS

A total of 519 patients referred to the university clinic for hypertension were screened for renovascular hypertension with 405 captopril challenge tests (CCT) and 450 captopril renographies (CRG).

INTERVENTIONS

Abdominal angiography was performed on 84 patients for positive screening. Fifteen patients underwent angiography for a sole suspicious clinical presentation. The angiography revealed 17 renal artery stenoses and five occlusions in 20 patients. Fifteen technically successful angioplasties and three nephrectomies were performed.

RESULTS

In the patients who underwent angiography, CCT had a specificity of 39% and a sensitivity of 67% for renovascular hypertension. CRG had a sensitivity of 100% and a specificity of 68%. In the whole study population, the estimated specificity of CCT was 88% and that of CRG 95%. Invasive treatment reduced systolic/diastolic blood pressure from 157/99 to 140/87 mmHg and the number of antihypertensive drugs used from 2.6 to 1.4 in 16 patients (mean age 49 years). Angiotensin converting enzyme (ACE) inhibition was effective in four elderly patients. Cost-efficacy analysis Screening with CRG and invasive treatment cost US$15400 per successful invasive treatment Equally effective pharmacological treatment would have cost US$10400. Limiting the screening with CRG to the 173 patients with no obvious renal parenchymal disease and with hypertension at a younger age (< or =30 years) or unresponsive to two antihypertensive drugs (diastolic blood pressure > 90 mmHg) would have yielded a prevalence of 12% and missed only one elderly patient who responded to ACE inhibition. The limited screening, along with invasive treatment, would have cost US$7300 per patient

CONCLUSIONS

CRG is superior to CCT for screening of renovascular hypertension. Screening with CRG is cost-effective when limited to patients with no obvious renal parenchymal disease and with hypertension that does not respond to two antihypertensive drugs or is detected in patients no older than 30 years.

Renal artery stenosis: changes in intrarenal Doppler waveform following percutaneous transluminal angioplasty

PURPOSE

To examine the extent of the changes in the intrarenal spectral waveform patterns after percutaneous transluminal angioplasty (PTA) and whether there is a correlation with the angiographic and clinical results.

METHODS

In 44 patients with 68 PTAs we analyzed the intrarenal spectral waveform regarding the existence of a tardus-parvus pattern before and after PTA.

RESULTS

In 51 of the 60 cases with a tardus-parvus pattern prior to PTA, a complete normalization of the spectral wave-form was noted. There was no correlation between the Doppler result after PTA and the angiographic and clinical result. In contrast there was a significant correlation between the Doppler result before PTA and the clinical outcome: patients with a normal intrarenal spectral waveform before PTA showed no improvement in their arterial hypertension.

CONCLUSION

Our results indicate that a patient with a normal spectral waveform analysis does not response to PTA. However, there is still an unpredictable clinical response even if a patient has an abnormal intrarenal spectral waveform prior to PTA and a complete normalization after PTA.

Renal anatomic changes on magnetic resonance imaging and gadolinium-enhanced magnetic resonance angiography after renal revascularization. Original investigation

RATIONALE AND OBJECTIVES

The anatomic and hemodynamic renal changes after renal arterial revascularization (RAR) were investigated.

METHODS

Thirty-seven kidneys and 40 renal arteries were evaluated in 20 patients by using magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) to assess pre- and post-RAR renal length and mass, parenchymal thickness, renal enhancement, renal artery caliber, poststenotic dilation, and signal dephasing on 3D phase contrast (PC). The kidneys and renal arteries were segregated into three groups. Group 1 included 16 patients who benefited from RAR (defined as clinical improvement based on decreased serum creatinine or fewer number of antihypertensive medications) in whom 26 renal arteries in 25 kidneys were studied. Intervention included renal artery endarterectomy (n = 20); aortorenal bypass (n = 3); renal artery reimplantation (n = 3); and percutaneous transluminal angioplasty (PTA; n = 1). A total of 27 interventions was performed, as PTA failed for one patient who subsequently underwent aortorenal bypass before reimaging. Group 2 included four patients who did not clinically benefit. A total of eight revascularized arteries were studied in seven kidneys. In group 3, six renal arteries in five kidneys from groups 1 and 2 without RAS/RAR were analyzed as an internal control.

RESULTS

Technical success (defined as increased vessel caliber after intervention) was achieved in 33 of the 34 revascularized arteries. A statistically significant increase in renal length occurred regardless of clinical outcome (pre-RAR, 9.5 cm; post-RAR, 10.5 cm; P < 0.0001). Parenchymal thickness and renal mass, however, improved only in patients who benefited clinically from RAR. Parenchymal enhancement was unchanged in any of the groups studied. No significant morphologic changes were detected in the control group.

CONCLUSIONS

Magnetic resonance imaging and Gd-MRA detect anatomic and hemodynamic changes that occur with renal revascularization.

Contrast-enhanced magnetic resonance angiography of the renal arteries. Original investigation

RATIONALE AND OBJECTIVES

The authors determine the value of contrast-enhanced, three-dimensional (3D) magnetic resonance angiography (MRA) in the assessment of the renal arteries in comparison with conventional arteriography (CA).

METHODS

One hundred three patients (71 m, 32 f) were evaluated with both CA and 3D MRA. The 3D MRA data set consisted of 44 contiguous sections, acquired in apnea (23-28 seconds) using the following parameters: TR/TE 3.9/1.5 milliseconds, flip angle 40 degrees to 50 degrees, 3/4 k-space acquisition. A bolus of 0.3 mmol/kg BW gadolinium-DTPA was administered intravenously, using an automated injector. A test bolus method was used for timing of the bolus relative to the beginning of the data acquisition. Intra-arterial CA was used as the standard of reference in all patients. Separate interpretations of the CA and MRA results were made by two different pairs of radiologists, who were each blinded to the results of the other exam.

RESULTS

In all, 31 of 33 accessory renal arteries were correctly identified. All 205 main renal arteries were seen with MRA. Of 65 significant stenoses identified on CA, 61 were correctly identified and graded by MRA. Sensitivity and specificity values for the assessment of significant renal arterial lesions were 93% and 90%, respectively.

CONCLUSIONS

Breath-hold, contrast-enhanced 3D MRA allows for the reliable assessment of renal arterial morphology and pathologic states.

Ostial renal artery stent placement for atherosclerotic renal artery stenosis in patients with coronary artery disease

To test the utility of endoprosthetic treatment for ostial renal artery stenosis, and to examine blood pressure and its treatment, serum creatinine, and restenosis rate, 44 ostial renal stent placements were performed in 30 patients with concomitant coronary artery disease, arterial hypertension, and the indication for angiotensin converting enzyme (ACE) therapy. There was a marked decrease in systolic and diastolic blood pressure (163+/-30 to 145+/-17 and 93+/-18 to 83+/-10 mm Hg; P < 0.008) with a decrease in number of medication (3.2+/-0.9 to 2.8+/-1.0; P = 0.005). In 5 out of 8 patients not receiving an ACE inhibitor, this drug could be added. Serum creatinine changed from 1.46+/-0.7 mg/dl to 1.39+/-0.58 mg/dl (P = ns). Three patients showed restenosis (12.5%). Ostial stenting lowers blood pressure, decreases antihypertensive drugs and increases medication flexibility.

Optimizing three-dimensional gadolinium-enhanced magnetic resonance angiography. Original investigation

RATIONALE AND OBJECTIVES

This primarily theoretical work examines three-dimensional gadolinium-enhanced magnetic resonance angiography f8p4Gd-MRA) with the goal of understanding how to achieve the best possible images with respect to signal to noise ratio (SNR) and k-space induced artifacts. Patient variables, contrast injection schemes, and pulse sequence parameters are considered for this purpose.

METHODS

A theoretical analysis, including computer simulation, describes how contrast material injection profiles influence 3D Gd-MRA images, both in terms of intravascular signal and resultant artifacts. Further theoretical analysis of the spoiled gradient refocused pulse sequence describes how to maximize SNR. Clinical imaging complements computer modeling.

RESULTS

Equations were derived relating contrast injection parameters and pulse sequence variables to SNR and artifacts. For present imaging equipment, administering contrast material over a duration of 60% to 80% of the total imaging time and using fractional echo techniques gives the best SNR without significantly sacrificing image quality.

CONCLUSIONS

Three-dimensional Gd-MRA can be tailored to a specific clinical situation and imaging system through the use of proper breath-holding, bolus timing, Gd administration, and pulse sequence design.

Arterial-phase three-dimensional gadolinium magnetic resonance angiography of the renal arteries. Strategies for timing and contrast media injection: original investigation

RATIONALE AND OBJECTIVES

The authors review different imaging and contrast-media infusion strategies for arterial-phase three-dimensional (3D) gadolinium-enhanced magnetic resonance angiography (Gd-MRA).

METHODS

The influence of physicochemical factors on the infusion of contrast media, including viscosity, flow rate, inline pressure, and cannula size, is assessed. The combination of manual or automated contrast-media administration with timing-dependent or -independent 3D Gd-MRA techniques is reviewed regarding the aspects of effectiveness, robustness, image quality, and costs.

RESULTS

For effective bolus delivery with high flow rates, the type and temperature of the contrast media, the size of the cannula, and an immediate saline flush must be considered. Timing-dependent techniques based on a test bolus and using automated contrast-media infusion as well as timing independent techniques such as MR SmartPrep or multiphase 3D Gd-MRA by using a manual injection with a SmartSet tubing set, are all effective procedures for arterial phase 3D Gd-MRA.

CONCLUSIONS

Manual contrast-media injection with a tubing set can be used for timing-independent MRA techniques. The multiphase 3D Gd-MRA approach seems to be favorable for different MR systems, robustness, and speed.

Detection of renal arteries with fast spin-echo magnetic resonance imaging

With the increasing use of non-invasive imaging with MR and volumetric CT to evaluate renal arteries, the ability to accurately detect the number and state of native renal arteries becomes critical if conventional angiography is to be supplanted in these settings. The present study evaluated the utility of a fast spin-echo (FSE) T2-weighted sequence to detect the number and course of renal arteries and their ostia compared to conventional angiography. Ten patients underwent conventional catheter angiography either for renal artery stenosis evaluation or as potential renal donors. Each patient then had an MR study of the renal arteries and kidneys with FSE MR (TR = 4000 ms, TE = 102 ms, eight-echo train length, 5-mm-thick interleaved 128 phase encodes, superior and inferior saturation pulses, number of excitations (NEX) = 4, on a 1.5-T superconducting magnet (GE, Milwaukee, WI, USA). Images were reviewed by two 'blinded' radiologists and renal arteries were counted and their ostia were evaluated. Results were compared with angiography and inter- and intra-observer statistics were calculated. All 10 patients underwent MR successfully, nine for renal artery stenosis (RAS) evaluation and one was a renal donor. A total of 24 renal arteries were imaged in 19 kidneys. Fast spin-echo MR is 95% accurate (95% CI: 88-100%) in detection of renal arteries, with no statistical difference between FSE MR and catheter angiography (McNemar P = 0.0). Inter- and intra-observer statistics demonstrate good-to-excellent agreement in renal artery detection (kappa: 0.63-0.90). In one case of RAS evaluation an incidental adrenal mass was detected as the aetiology of the patient's hypertension. Fast spin-echo MR can be a useful adjunct as part of the imaging for renal arteries with MRI.

[First clinical results of ultrafast, contrast-enhanced 2-phase 3D-angiography of the abdomen]

PURPOSE

To assess the utility of breath-hold abdominal ultrafast three-dimensional (3D) gadolinium-enhanced dual-phase magnetic resonance angiography (MRA).

MATERIAL AND METHODS

125 patients with various abdominal pathologies were imaged using a breath-hold ultrafast gadolinium-enhanced dual-phase 3D-MRA technique.

RESULTS

119 (95%) of 125 MRA's were of good or excellent quality. The sensitivity in the detection of renal artery stenoses as well as stenoses of the celiac trunk and the superior mesenteric artery was 100%. Accessory renal arteries (n = 9) and replaced hepatic arteries (n = 4) were reliably detected by MRA. In 24 (71%) of 34 cases MR-angiographic delineation of the spleno-portal system and hepatic veins was superior compared to conventional angiography.

CONCLUSION

Breath-hold gadolinium-enhanced dual-phase 3D-MRA has the potential to replace conventional angiography in the abdomen.

Risk of morbidity from renovascular disease in elderly patients with congestive cardiac failure

BACKGROUND

Renovasular disease commonly affects elderly people. Elderly patients with heart failure are routinely treated with angiotensin-converting-enzyme (ACE) inhibitors, which may increase risk of renal dysfunction. We investigated the frequency of renovascular disease among elderly people with heart failure.

METHODS

From the local population of Salford, UK, we recruited 86 patients with heart failure with a mean age of 77.5 (SD 5.6) years, who were admitted as acute emergencies or who attended general medical clinics. We selected patients by intention to treat with ACE inhibitors. We used captopril renography to screen for renovascular disease. All patients with abnormal renograms underwent magnetic-resonance angiography of the renal arteries as well as 40% of patients with normal renograms as negative controls.

FINDINGS

Magnetic-resonance angiography showed severe renovascular disease (>50% renal-artery stenosis or occlusion) in 29 (34%) patients. Captopril renography had an estimated sensitivity of 78.8% (95% CI 72.7-97.8) and specificity of 94.3% (67.6-97.3) for detection of renovascular disease. The estimated positive predictive value of captopril renography was 89.7% and the negative predictive value was 87.5%. Patients with renovascular disease had worse renal function (mean creatinine 201 [SD 56] vs 136 [40] pmol/L, p<0.001), were older (mean age 80.7 [5.6] vs 76.8 [5.3] years, p<0.01), and were more likely than patients without renovascular disease to have peripheral arterial disease.

INTERPRETATION

Some elderly patients with occult renovascular disease on ACE inhibitors will be at risk of developing uraemia. Renal function should be closely monitored to detect any deterioration early.