Multidetector CT angiography of arterial inflow and runoff in the lower extremities: a challenge in data acquisition and evaluation

Is the Endovascular Treatment of Mild Iliac Stenoses Worthwhile to Improve Wound Healing in Patients Undergoing Femorotibial Bypass?

BACKGROUND

After an infrapopliteal reconstruction, minor amputations are frequently required, but even in the case of successful revascularization, wound healing is a major concern. We studied the role of iliac artery inflow correction in patients undergoing infrapopliteal vein grafts to improve the heal of midfoot amputation.

METHODS

Thirty-eight patients affected with Rutherford grade III category 5 peripheral arterial disease, who underwent successful simultaneous iliac endovascular procedure, infrapopliteal reversed vein bypass graft, and minor amputation, were enrolled in this retrospective study. The population was divided in group 1 (20 patients) with inflow vessels Trans-Atlantic Inter-Society Consensus Document on Management of Peripheral Arterial Disease (TASC) II type B atherosclerotic lesions and group 2 (18 patients) with TASC II type A atherosclerotic lesions determining an invasive pressure drop greater than 15 mm Hg. Fifteen patients (group 3) undergoing infrapopliteal reversed vein bypass graft without associated inflow procedures (TASC II type A and invasive pressure drop greater than 15 mm Hg) were matched with group 2 based on propensity score. Healing was calculated by subtracting the final ulcer area from the initial ulcer area and dividing by the number of follow-up months to obtain the total area healed per month (cm²/month). Stepwise logistic regression analysis adjusted for demographics and medical comorbid conditions was used to test the association between wound healing and treatment modalities.

RESULTS

Forty-three patients were available for further analysis. Ten patients were excluded because of graft occlusion with consequent impairment of wound healing. After midfoot amputations, mean wound diameter was 20 ± 8 cm², and mean healing time was 10 ± 4 months (range 3-20 months; median 9 months). Wounds of groups 1 and 2 healed faster than those of group 3 at 4 and 8 months (P < 0.02 and P < 0.001, respectively; P < 0.04 and P < 0.001, respectively). Multivariate analysis demonstrated the association between wound healing and inflow correction (P < 0.001).

CONCLUSIONS

An aggressive treatment is necessary to obtain the heal of the ischemic wounds. The most important predictive factor for nonhealing wounds is the absence of inflow correction. We demonstrated that the inflow should be also corrected in the presence of subclinical lesions.

Determination of the Best Parameter for Defining the Hemodynamic Significance of an Iliac Artery Stenosis Detected on Computed Tomography Angiography

PURPOSE

The purpose of this study was to determine the best parameter, derived from computed tomography angiography (CTA) for accurate prediction of a hemodynamically significant stenosis of the common or external iliac artery.

METHODS

A retrospective keyword search was performed on the Radiology Information System at our tertiary academic medical centre. Reports from January 2008 to September 2013 were searched using the keywords iliac, stenosis, and pressure. Patients who had both and CTA and a pelvic angiogram with pressure measurements obtained across a potential stenosis were selected. Using 3D postprocessing software (TeraRecon, Foster City, CA), the CTAs were analysed for the following parameters of each lesion: minimum diameter of stenosis, minimum cross-sectional area of stenosis, percent narrowing of vessel diameter, and percent reduction in vessel area. The percent stenosis was calculated in reference to the outer diameter at the point of maximal narrowing and also in reference to a normal segment of vessel more distal to the stenosis. These parameters were then compared with the measured pressure gradient using receiver-operating characteristic analysis and the Mann-Whitney U test to determine which best predicted a significant stenosis, defined as a greater than 10% drop in systolic pressure across a lesion.

RESULTS

One hundred and two stenoses in 83 patients (26 women, 57 men; 47-88 years old) were identified. Mean diameter of the stenosis was 2.8 mm for significant stenosis compared to 3.8 mm in nonsignificant stenoses (P = .005). Mean minimum area for significant stenoses was 11.8 mm(2) compared to 17.22 mm(2) for nonsignificant stenoses (P = .032) No other variables showed a significant difference between significant and nonsignificant stenoses. A minimum diameter of ≤4.0 mm at the level of a stenosis is 92% sensitive and 48% specific for predicting a hemodynamically significant iliac artery stenosis, with a positive predictive value of 88%.

CONCLUSIONS

A simple measurement of the minimum diameter of an iliac artery at the level of stenosis is the best predictor of the hemodynamic significance of a stenosis in the common or external iliac artery.

Visualization of the segment IV hepatic artery using 128-section MDCT angiography

AIM

To visualize the segment IV hepatic artery and to evaluate the variations in anatomy using multidetector computed tomography (MDCT) angiography.

MATERIALS AND METHODS

Six hundred and seventeen patients (381 men and 236 women; mean age 62.7 ± 8.1 years; age range 22-92 years) who underwent MDCT angiography performed using a 128-section MDCT system were included in the study. The segment IV hepatic arteries of 453 patients with adequate image quality were displayed using volume rendering (VR), maximum intensity projection (MIP), and multiplanar reconstruction (MPR), and were analysed regarding the origination and variation of the arteries by two radiologists and an anatomist retrospectively.

RESULTS

Segment IV arteries were categorized into five different types according to their points of origin: left hepatic artery (LHA, 51.66%), right hepatic artery (RHA, 30.68%), proper hepatic artery (PHA, 5.3%), dual (12.14%), and triple (0.22%). Segment IV arteries arising from normal LHA, RHA, and PHA were found in 73.73% of patients, and those arising from variant LHA or RHA were found in 26.27%. The patterns RN2, LA2, LA3, LA4, PN2, PV1, DA1, DA2, DV3, and DV4 were first reported in the present study.

CONCLUSIONS

MDCT angiography can evaluate normal as well as anatomical variants of segment IV arteries. Predicting arterial patterns of segment IV of the liver is important in planning and performing all radiological and surgical procedures in the liver, especially in hemi-liver graft procedures.

Low contrast volume run-off CT angiography with optimized scan time based on double-level test bolus technique--feasibility study

PURPOSE

To verify the technical feasibility of low contrast volume (40 mL) run-off CT angiography (run-off CTA) with the individual scan time optimization based on double-level test bolus technique.

MATERIALS AND METHODS

A prospective study of 92 consecutive patients who underwent run-off CTA performed with 40 mL of contrast medium (injection rate of 6 mL/s) and optimized scan times on a second generation of dual-source CT. Individual optimized scan times were calculated from aortopopliteal transit times obtained on the basis of double-level test bolus technique--the single injection of 10 mL test bolus and dynamic acquisitions in two levels (abdominal aorta and popliteal arteries). Intraluminal attenuation (HU) was measured in 6 levels (aorta, iliac, femoral and popliteal arteries, middle and distal lower-legs) and subjective quality (3-point score) was assessed. Relations of image quality, test bolus parameters and arterial circulation involvement were analyzed.

RESULTS

High mean attenuation (HU) values (468; 437; 442; 440; 342; 274) and quality score in all monitored levels was achieved. In 91 patients (0.99) the sufficient diagnostic quality (score 1-2) in aorta, iliac and femoral arteries was determined. A total of 6 patients (0.07) were not evaluable in distal lower-legs. Only the weak indirect correlation of image quality and test-bolus parameters was proved in iliac, femoral and popliteal levels (r values: -0.263, -0.298 and -0.254). The statistically significant difference of the test-bolus parameters and image quality was proved in patients with occlusive and aneurysmal disease.

CONCLUSION

We proved the technical feasibility and sufficient quality of run-off CTA with low volume of contrast medium and optimized scan time according to aortopopliteal transit time calculated from double-level test bolus.

Assessment of intracranial arterial stenosis with multidetector row CT angiography: a postprocessing techniques comparison

BACKGROUND AND PURPOSE

It was demonstrated the some patients with stroke have intracranial stenosis of 50% or greater and the identification of intracranial arterial stenosis is extremely important in order to plan a correct therapeutical approach. The aim of this study was to assess the image quality and intertechnique agreement of various postprocessing methods in the detection of intracranial arterial stenosis.

MATERIAL AND METHODS

Eighty-five patients who were studied by using a multidetector row CT scanner were retrospectively analyzed. A total of 2040 segments were examined in the 85 subjects. Intracranial vasculature was assessed by using MPR, CPR, MIP, and VR techniques. Two radiologists reviewed the CT images independently. Cohen weighted kappa statistic was applied to calculate interobserver agreement and for image accuracy for each reconstruction method. Sensitivity, specificity, PPV, and NPV were also calculated by using the consensus read as the reference.

RESULTS

Two hundred fifteen (10.5%) stenosed artery segments were identified by the observers in consensus. The best intermethod kappa values between observers 1 and 2 were obtained by VR and MIP (kappa values of 0.878 and 0.861, respectively), whereas MPR provided the lowest value (kappa value of 0.282). VR showed a sensitivity for detecting stenosed segments of 88.8% and 91.6% for observers 1 and 2, respectively. The highest positive predictive value was also obtained by VR at 95% and 99% for observers 1 and 2, respectively. Image accuracy obtained by using VR was the highest among all reconstruction methods in both observers (185/255 and 177/255 for observers 1 and 2, respectively).

CONCLUSIONS

The results of our study suggest that VR and MIP techniques provide the best interobserver and intertechnique concordance in the analysis of intravascular cranial stenosis.

Lower Extremity Arterial Disease: Multidetector CT Angiography—Meta-Analysis

PURPOSE

To obtain the best available estimates of the diagnostic performance of multidetector computed tomographic (CT) angiography compared with that of digital subtraction angiography (DSA) in the assessment of symptomatic lower extremity arterial disease and to identify the most important sources of variation in diagnostic performance between studies.

MATERIALS AND METHODS

Reports of studies published from January 2000 through April 2006 in English, German, French, or Spanish were searched for by using the MEDLINE, EMBASE, and Cochrane databases. Studies were included if they allowed construction of 2 x 2 contingency tables for the detection of stenosis of 50% or greater at multidetector CT angiography compared with that at DSA -- the reference standard -- in patients with claudication or critical ischemia. Two observers extracted data about study design, patient characteristics, arterial tracts, and technical protocols. Random-effects summary receiver operating characteristic analysis was performed to examine the influence of these data on diagnostic performance.

RESULTS

Of the 70 studies initially identified, 12 were included in which multidetector CT angiography was used to evaluate 9541 arterial segments in 436 patients. The pooled sensitivity and specificity for detecting a stenosis of at least 50% per segment were 92% (95% confidence interval: 89%, 95%) and 93% (95% confidence interval: 91%, 95%), respectively. Three studies provided data about the diagnostic performance of multidetector CT angiography in subdivisions of the arterial tract. The diagnostic performance of multidetector CT angiography in the infrapopliteal tract was lower than but not significantly different from that in the aortoiliac (P > .11) and femoropopliteal (P > .40) tracts. Regression analysis showed that diagnostic performance was not significantly influenced by differences in study characteristics.

CONCLUSION

Multidetector CT angiography is an accurate diagnostic test in the assessment of arterial disease (> or =50% stenosis) of the entire lower extremity.

The role of 3D-CTA in the assessment of peripheral vascular lesions in trauma patients

PURPOSE

The goal of any imaging in the setting of a level 1 trauma center is to assess the injuries of a patient as fast as possible with the least amount of time spend to move the patients between rooms or scanners in order to reduce the time till final diagnosis. CT-angiography (CTA) has become increasingly used to analyze peripheral vascular lesions in blunt and penetrating trauma.

METHODS

Diagnostic angiography and CTA are competing methods for the display of peripheral vascular lesions. The specific advantages and shortcomings of both techniques for the routine use in a trauma center are discussed.

RESULTS

The inherent limitations of the spatial and temporal resolution of a CTA are compensated by the availability of the procedure and reduced time needed for the final diagnosis.

CONCLUSION

3D-CTA with multislice CT (MSCT) can be used to replace the diagnostic angiography in patients with blunt or penetrating extremity injuries.

Multi-detector row computed tomography angiography of peripheral arterial disease

With the introduction of multi-detector row computed tomography (MDCT), scan speed and image quality has improved considerably. Since the longitudinal coverage is no longer a limitation, multi-detector row computed tomography angiography (MDCTA) is increasingly used to depict the peripheral arterial runoff. Hence, it is important to know the advantages and limitations of this new non-invasive alternative for the reference test, digital subtraction angiography. Optimization of the acquisition parameters and the contrast delivery is important to achieve a reliable enhancement of the entire arterial runoff in patients with peripheral arterial disease (PAD) using fast CT scanners. The purpose of this review is to discuss the different scanning and injection protocols using 4-, 16-, and 64-detector row CT scanners, to propose effective methods to evaluate and to present large data sets, to discuss its clinical value and major limitations, and to review the literature on the validity, reliability, and cost-effectiveness of multi-detector row CT in the evaluation of PAD.

Multidetector-Row CT Angiography Diagnostic Sensitivity in Evaluation of Renal Artery Stenosis

PURPOSE

The aim of this study was to assess the image quality and interobserver agreement of various multidetector-row computed tomographic angiography postprocessing techniques in the diagnosis of renal artery stenosis (RAS).

MATERIALS AND METHODS

We studied 36 patients (21 men and 15 women; mean age, 49 years) who underwent computed tomography angiography to assess renal arteries for suspected RAS. Patients were analyzed by using a multidetector-row computed tomography. Computer tomographic scans were obtained after intravenous bolus administration of 110 to 140 mL of nonionic contrast material using a 4- to 6-mL/s flow rate. We assessed every patient by using axial scans, multiplanar reconstruction (MPR), maximum intensity projection (MIP), and volume rendering (VR) techniques. For each patient and for each reconstruction method, the image quality of the main renal artery was scored as 0 for bad-quality, 1 for poor-quality, 2 for good-quality, and 3 for excellent-quality images. Two radiologists reviewed computed tomographic images independently. We calculated interobserver agreement and kappa value. We correlated the stenosis degree observed by the 2 readers with the type of reconstruction used.

RESULTS

Overall number of renal arteries studied was 72, and we detected 24 RAS. Quality images obtained an overall (averaged between the 2 observers) value of 133 of 216, 163 of 216, and 145 of 216 for MPR, MIP, and VR, respectively. Our data underlined a statistical difference between MPR images and VR images (P < 0.001). Moreover, we noticed that the images classified as excellent were obtained from a vessel with 350 Hounsfield units or higher. Kappa value was good in MIP and VR methods evaluation but poor with the use of MPR.

CONCLUSIONS

Reformatting techniques usually provided a high visual impact, and in our study, MIP and VR showed the best diagnostic interobserver agreement in quality and reproducibility of stenosis degree.

MDCT angiography of the spinal vasculature and the artery of Adamkiewicz

OBJECTIVE

The purpose of our study was to prospectively assess 40-MDCT technology in combination with adapted brain reconstruction algorithms to visualize the spinal vasculature, in particular the artery of Adamkiewicz and its anatomic variants.

SUBJECTS AND METHODS

One hundred patients underwent contrast-enhanced MDCT of the thoracolumbar junction with collimation of 40 x 0.625 mm. The adapted brain algorithm reconstructed the spinal canal with a field of view of 90 mm at 0.6-mm slice thickness. Curved multiplanar reformations identified the artery of Adamkiewicz as a continuous vascular tract extending from the aortic orifices of the intercostal or lumbar arteries via the anterior radiculomedullary artery to the anterior spinal artery. Segment of origin and length were noted. Diameter and contrast-to-noise ratio (CNR) were evaluated along the posterior branch, the radiculomedullary artery, the artery of Adamkiewicz, and the anterior spinal artery. Univariate general linear model analysis with Bonferroni post hoc corrections evaluated whether laterality, segment of origin, and length of the artery of Adamkiewicz showed a sex-specific propensity. Multivariate general linear model analysis assessed whether spinal vascular diameters and intraluminal CNR showed correlations with sex, laterality, and segment of origin. Finally, the luminal diameters of the feeding posterior branches were statistically compared with those of the ipsilateral and contralateral adjacent posterior branches.

RESULTS

Successful depiction of the artery of Adamkiewicz was achieved in all patients; longitudinally the artery measured 40.1 +/- 13.51 mm. In 63% of patients it originated from the left side of the body, and in 74% it originated from the level of the 10th-12th thoracic vertebrae. Duplications were found in 5% of patients. Segmental distribution, laterality, and length did not show significant sex-specific differences (p > 0.05). The vascular diameter and luminal contrast did not show significant differences caused by sex, laterality, or segment of origin (p > 0.05). The diameter of the posterior branches (2.8 +/- 0.71 mm) arising in the segments of origin showed a significantly wider lumen than any of the other posterior branches (contralateral, 1.9 +/- 0.32 mm; upper ipsilateral, 2.0 +/- 0.47 mm; lower ipsilateral, 1.9 +/- 0.39 mm) (p < 0.0001).

CONCLUSION

Contrast-enhanced 40-MDCT technology, in combination with an adapted brain reconstruction algorithm, can depict the artery of Adamkiewicz and its anatomic variants.

Preliminary examination to determine the suitable contrast material injection protocol for CT angiography of the pelvis and lower extremities with a multidetector row helical scanner

PURPOSE

The aim of this study was to determine the best of three protocols for the depiction of arteries in the pelvis and lower extremities by computed tomographic angiography (CTA) with a multidetector row helical scanner.

MATERIALS AND METHODS

CTA was performed in five asymptomatic volunteers using a four-channel multidetector row helical scanner. Low-osmolar iodinated contrast material was injected at the flow rate of 3 ml/s using three protocols: 100 ml of 300 mg I/ml, 150 ml of 300 mg I/ml, and 100 ml of 350 mg I/ml. The CT number of opacified blood was measured at six levels. Three doctors independently assessed the degree of depiction of arteries on CTA images without knowing the protocol using a 3-point scale.

RESULTS

CT numbers at the level of the popliteal artery on the protocol of 150 ml of 300 mg I/ml were significantly greater than the others. The mean score for the depiction of trifurcation on the protocol of 150 ml of 300 mg I/ml was significantly greater than those in the others.

CONCLUSION

The protocol of 150 ml of 300 mg I/ml was the best for depicting arteries in the pelvis and lower extremities by CTA.