European Journal of Cardiovascular Medicine

In the developing world, peripheral arterial disease (PAD) is a major health issue that is becoming more prevalent as a result of rising risk factors. Minor impairments to limb loss are among its complications. The primary cause of PAD is atherosclerosis. Lower extremities artery disease affects more than 200 million people globally, with symptoms ranging from mild to severe.1, 2

PAOD is prevalent, especially in the elderly, and carries a significant risk of amputation, long-term suffering, and early mortality. Although relatively rare in youth, PAOD affects a significant percentage of the senior population and becomes more common as people age. High levels of C-reactive protein (CRP), hypertension, dyslipidemia, hypercoagulable states, smokers, diabetics, renal insufficiency, and homocystinuria are among the conditions that increase the risk of developing PAOD3.

Atherosclerosis, thromboembolic illness, trauma, especially in young adults, and acute arterial occlusion, which may result from embolic occlusion, are the causes of peripheral arterial stenosis or occlusion. (e) Small and medium-sized arteries are impacted by arteritis such as Thromboangiitis Obliterans (TAO); (f) Type 2 Diabetes Mellitus4.

The size of the occluded arterial and whether the stenosis or occlusion develops abruptly (acute) or gradually (chronic), with the artery gradually narrowing over time, are factors that affect how severe the symptoms are. Additionally, symptoms and indicators of the illness affecting the organ that the artery supplies. Example (a): Temporary ischemic stroke assaults, (b) Angina in the heart (c) Hypertension and renal failure in the kidneys (d) Intestine: severe pain and infarction in the abdomen4.

Imaging plays a crucial role in the evaluation of patients with peripheral arterial diseases.Colour Doppler ultrasonography is the initial modality of choice in for Peripheral vascular disease(PVD) investigation ,despite its wide use it has lower sensitivity than MDCT angiography which is considered as the upcoming modality in the evaluation of lower extremity PVD.

MDCT Angiography is regarded as the promising modality in lower extremity arterial imaging. It is a reliable noninvasive tool in quantifying the length, numbering grade of stenosis.

It mainly delineates the presence or absence of significant obstruction to the blood flow, the site and anatomical extent of obstruction, the status of collaterals and distal vasculature which is crucial for planning the treatment as well as to monitor the results of therapy and disease progression.

Aim: Comparison of CT angiography and colour doppler ultrasonography in evaluation of Peripheral arterial diseases.

Objectives:

1. To compare the efficacy of MDCT Angiography and Colour Doppler ultrasonography in diagnosing and assessing the severity of peripheral arterial diseases of lower limb.
2. To assess the reliability of colour Doppler ultrasound of lower limb arteries in patients of peripheral arterial diseases.

REVIEW OF LITERATURE

In 2012, Ayman et al27 conducted a similar study where 16 patients (12 males & 4 females) with an age range of 33–75 years were included. Study reported that 98.7% agreement between the findings of DSA and MDCT angiography. While agreement between DSA and CCD was 96.1%.

In 2012, Arda et al28 included a total of 774 vessel segments were imaged by both modalities. When all arteries were considered, MDCTA detected obstructed or stenotic lesions in 16.8% of arteries, versus 11.1% compared to DUS. When suprapopliteal arteries alone were considered, MDCTA detected lesions in 15.0% of arteries, versus 11.0% with DUS. When infrapopliteal arteries only were considered, MDCTA detected lesions in 19.6% of arteries, versus 11.3% with DUS. MDCTA showed 5.7% (95% CI: [3.5%, 7.9%]) more lesions than DUS when all arteries were considered together, 8.3% (95% CI: [4.6%, 12.0%]) more lesions when only the infrapopliteal arteries were compared, and 4.0% (95% CI: [1.3%, 6.8%]) more lesions when only suprapopliteal arteries were compared (p < 0.01 for all comparisons).

In 2016, Chiambaram et al29 conducted a similar study to compare arterial diseases of extremities using Doppler ultrasound and CT angiography, and to find the better non-invasive modality of choice. Study reported that Doppler overestimated narrowing by one grade in 47 segments, by two grade in 11 segments, by three grades in 30 segments and by four grades in 22 segments; underestimated by one grade in 28 segments, by two grades in 9 segments, by three grades in 5 segments and by four grades in 3 segments. Significant statistical difference exists between Doppler USG and CT angiography. Doppler showed good correlation with CT angiography in 74%, but, Doppler overestimated stenosis grade in a significant percentage. The sensitivity, specificity and accuracy of Doppler USG compared with CT angiography was 93.36%, 82.44%, and 86.42%.

In 2016, Rezia et al30 reported that ost of the arteries showed good total agreement between Doppler and MDCT angiography. Aortoiliac group of vessels showed more than 80% total agreement between Doppler and MDCT angiography. Femoropopliteal group vessels showed more than 75% total agreement. Infrapopliteal group of vessels showed more than 50% total agreement.

In 2020, Kondeti et al31 reported that Out of the total 1680 vessel segments in 80 patients, color Doppler sonography (CDS) was able to detect 545 (32.4%) positive segments, in comparison to the CTA which was able to detect 732 (43.5%) bilaterally, with 11.1% of cases detected more on MDCT angiography predominantly grade-2, 3, 4, except for grade-1. On overall except for wall thickness, MDCT angiography was better in detecting wall calcification, occlusion, and thrombus on comparison with CDS.

The study was a comparative study done on 40 patients with signs and symptoms of peripheral arterial occlusive disease referred for evaluation by imaging by colour doppler ultrasonography and MDCT angiography to the department of Radiodiagnosis at MNR Medical College Hospital were included in the study.

INCLUSION CRITERIA:

• Patients presenting with Claudication pain.
• Patients with gangrene
• Patients with absent peripheral pulses
• Patients with risk factors

EXCLUSION CRITERIA:

• Polytrauma patients with suspected acute arterial injury.
• Patients contraindicated for CT scan
• Patients with history of contrast induced toxicity
• Patients with altered renal function test(RFT).
• Patients not willing for undergoing the CT and Ultrasound

METHODOLOGY

LOGIQ*F8 linear array(5-12Hz) probe. The lower limb arterial system will be examined and the Doppler waveform will be assessed.

The scan will be continued distally from common iliac artery to the common femoral artery assessing the superficial femoral artery ,anterior and posterior tibial arteres and dorsalis pedis artery using linear probe. The extent and severity of the arterial disease will be assessed.

GE 16 slice CT angiography is performed using non-ionic contrast.The scan direction will be craniocaudal from the level of infrarenal aorta to the pedal arch. The 150 ml of non-ionic contrast media will be injected.Images will be analyzed for plaques, extent and pattern of luminal narrowing and for the collateral flow.

For performing the Doppler scanning of the lower limb arterial system the patient was made to expose both the lower limbs in the supine position on the scanning couch.

Table 1: Age distribution

Table 1 shows distribution based on Age, 2.5% were <40 years of age, 25% were in the age group of 41-50 years, 15% in the age group of 51-60 years,45% in 61-70 years age group, 12.5% in >70 years age group.

Table 2: Gender distribution

Table 2 shows distribution based on gender, 72.5% are male and 27.5% are female.

Table 3: Distribution based on Grade of Claudication

Table 3 shows distribution based on Grade of claudication, 40% had Grade 2 claudication, 47.5% had grade 3 claudication, 12.5% had Grade 4 claudication.

Table 4: Distribution based gangrene

Table 4 shows distribution based on gangrene, 12.5% in the study had Gangrenous changes.

Table 5: Distribution based on tobacco intake and smoking history

Table 5 shows distribution based on Tobacco intake and smoking history, in the study 60% are smokers and 30% are tobacco chewer.

Out of 24 smokers, 58.3% smoke <20 pack years, 29.2% at 20-30 pack years, 12.5% smoke >30 pack years.

Table 6: Distribution based on clinically palpable pulses

Table 6 shows distribution based on clinically palpable pulses, In our study mostly the distal arteries were involved clinically as shown in the above graph in which 0 is absent; 1+ is diminished; 2+ is normal and 3+ is bounding respectively

Table 7: Distribution based on Co-morbidities

Table 7 shows distribution based on co morbidities, 27.5% are diabetic, 20% are HTN, 7.5% had IHD, 2.5% each had COPD, Acute MI, TB, Rheumatoid arthritis and Hepatitis B.

Table 8: Distribution based on Diagnosis

Table 8 shows distribution based on Diagnosis, 15% had TAO, 85% had Atherosclerosis

Table 9: Distribution based on doppler USG characteristics – Spectral wave form

Table 10: MDCT versus colour doppler USG – SFA

From the above table in comparison of colour doppler ultrasound versus MDCT, there is statistically significant difference in the detection of the extent of segment involvement in SFA

Table 11: MDCT versus colour doppler USG – DFA

From the above table in comparison of colour doppler ultrasound versus MDCT, there is statistically significant difference in the detection of the extent of segment involvement in DFA

Table 12: MDCT versus colour doppler USG – POP

From the above table between colour doppler ultrasound and MDCT, there is significant difference in the detection of the extent of segment involvement in popliteal artery.

Table 13: MDCT versus colour doppler USG – ATA

In comparison of colour doppler ultrasound versus MDCT, there is statistically extremely significant difference in the detection of the extent of segment involvement in ATA.

Table 14: MDCT versus colour doppler USG – PTA

From the above table in comparison of colour doppler ultrasound versus MDCT, there is statistically extremely significant difference in the detection of the extent of segment involvement in PTA.

Table 15: MDCT versus colour doppler USG – PA

From the above table in comparison of colour doppler ultrasound versus MDCT, there is statistically extremely significant difference in the detection of the extent of segment involvement in peroneal artery.

Table 16: MDCT versus colour doppler USG – DPA

From the above tables in comparison of colour doppler ultrasound versus MDCT, there is statistically significant difference in the detection of the extent of segment involvement in ATA

Table 17: Contralateral flow as detected by MDCT versus colour doppler ultrasound

Diagnostic accuracy of USG compared to MDCT to detect Contralateral flow

Table 18: Thrombosis by MDCT versus colour doppler ultrasound

Diagnostic accuracy of USG compared to MDCT to detect Thrombosis

CASE 1. : Representative images -CTA of tibioperoneal segments MIP reconstructed coronal images showing Grade III & IV stenosis of bilateral tibioperoneal segments

CASE 2: (A) MIP image of CTA showing bilateral mid SFA occlusion (B) 3D volume rendered image showing the same findings.

Based on prospective cohort study33

• 91,106 persons of all ages (97% of residential population, 94% white) registered with 63 family physicians in 9 general medical practices in Oxfordshire, United Kingdom followed from 2002 to 2005
• 1,657 persons (1.8%) developed 2,024 acute vascular events including 188 peripheral vascular events (43 aortic events, 53 embolic visceral or limb ischemic events, and 92 critical limb ischemia events)
• 12,886 (14%) of the persons > 65 years old had 78% of the peripheral vascular events
• 5,919 (6%) of the persons > 75 years old had 56% of the peripheral vascular events

Risk factors for PAD

Based on cohort study34

4,204,190 adults aged 30-90 years without history of cardiovascular disease having blood pressure measured at primary care practice between 1990 and 2013 were assessed 1.05% developed PAD during median follow-up 7 years Increased risk of PAD associated with

• Increased systolic blood pressure (adjusted hazard ratio [HR] 1.63, 95% CI 1.59-1.66 for each 20 mm Hg increase)
• Increased diastolic blood pressure (adjusted HR 1.35, 95% CI 1.31-1.38 for each 10 mm Hg increase)

Younger age and lower body mass index each associated with significantly greater risk of PAD.

This study reported that increased blood pressure associated with increased risk of PAD.

Based on cohort analysis of data from randomized trial35

33,357 patients ≥ 55 years old (mean age 67 years) with hypertension (median 146/84 mm Hg) and ≥ 1 other coronary artery disease risk factor in ALLHAT trial were assessed for time to first lower extremity PAD event

Coronary artery disease risk factors included history of myocardial infarction or stroke, history of coronary artery bypass grafting or angioplasty, diabetes mellitus, high- density lipoprotein < 35 mg/dL, left ventricular hypertrophy, and current cigarette smoking

All patients had blood pressure-lowering treatment (chlorthalidone, amlodipine, or lisinopril) and target blood pressure < 140/90 mm Hg

1,489 patients (4.5%) had lower extremity PAD event (defined as PAD-related hospitalization, procedure, medical treatment, or death) over median follow-up 4.3 years

Compared to systolic blood pressure 120-129 mm Hg Increased risk of PAD event associated with

• Systolic blood pressure ≥ 160 mm Hg (adjusted hazard ratio [HR] 1.21, 95% CI 1-1.48)
• Systolic blood pressure < 120 mm Hg (adjusted HR 1.26, 95% CI 1.05-1.52) No significant association between PAD event and
• Systolic blood pressure 130-139 mm Hg (adjusted HR 0.94, 95% CI 0.8-1.1)
• Systolic blood pressure 140-149 mm Hg (adjusted HR 1.08, 95% CI 0.91-1.27)
• Systolic blood pressure 150-159 mm Hg (adjusted HR 1.12, 95% CI 0.92-1.37) Compared to diastolic blood pressure 70-79 mm Hg
• Increased risk of PAD event associated with
• Diastolic blood pressure < 60 mm Hg (adjusted HR 1.72, 95% CI 1.38-2.16)
• Diastolic blood pressure 60-69 mm Hg (adjusted HR 1.18, 95% CI 1.02-1.37)

Decreased risk of PAD event associated with diastolic blood pressure 80-89 mm Hg (adjusted HR 0.85, 95% CI 0.75-0.97) no significant association between PAD event and

• diastolic blood pressure 90-99 mm Hg (adjusted HR 0.91, 95% CI 0.74-1.11)
• diastolic blood pressure ≥ 100 mm Hg (adjusted HR 0.71, 95% CI 0.46-1.08).

Study reported that high or low systolic blood pressure (≥ 160 mm Hg or < 120 mm Hg) and low diastolic blood pressure (< 69 mm Hg) may each be associated with increased risk of PAD event in patients with hypertension and ≥ 1 other coronary artery disease risk factor.

Based on systematic review36 of 55 observational studies (43 cross-sectional, 10 cohort, and 2 case-control) assessing relationship between cigarette smoking and PAD

Increased risk of PAD in

• Current smokers compared to never/nonsmokers (odds ratio 2.71, 95% CI 2.28-3.21) in analysis of 47 studies, results limited by significant heterogeneity
• Former smokers compared to never smokers (odds ratio 1.67, 95% CI 1.54- 1.81) in analysis of 29 studies, results limited by significant heterogeneity

Study reported that current and former cigarette smoking each associated with increased risk of PAD.

Based on prospective cohort study37

44,985 men aged 40-75 years without cardiovascular disease at baseline were followed for median 24.2 years

Clinically significant PAD defined as limb amputation or revascularization, angiographic vascular obstruction of ≥ 50%, ABI score < 0.9, or physician-diagnosed PAD

Cardiovascular risk factors included ever smoking, hypertension, hypercholesterolemia, and type 2 diabetes

537 patients (1.2%) developed PAD during follow-up and 96% had ≥ 1 risk factor at time of diagnosis

• each individual cardiovascular risk factor associated with increased risk of PAD (p < 0.05)
• each additional cardiovascular risk factor associated with increased risk of PAD (hazard ratio 2.06, 95% CI 1.88-2.26 [p < 0.001 for trend])

Ultrasound

Based on systematic review38 of 32 studies comparing contrast-enhanced MRA vs. digital subtraction angiography (DSA) (reference standard) for detection and exclusion of arterial steno-occlusions in 1,022 patients with PAD 6%-59% of arterial segments imaged had stenosis ≥ 50% by DSA

pooled predictive performance of contrast-enhanced MRA for detecting stenosis in per-segment analysis

• sensitivity 94.7% (95% CI 92%-96%)
• specificity 95.6% (95% CI 94% to 97%)
• positive likelihood ratio 21.56 (95% CI 15.7-29.7)
• negative likelihood ratio 0.056 (95% CI 0.037-0.083)

This study concluded that contrast-enhanced MRA may identify arterial stenosis in patients with PAD.

Based on cohort study3992 adults (mean age 64 years) had MRA of pelvis, thigh, and lower-leg for suspected or known PAD using both gadobenate dimeglumine 0.1 mmol/kg and gadopentetate dimeglumine 0.1 mmol/kg 31 patients also had conventional DSA 32% of 397 segments showed clinically relevant disease by reference standard gadobenate dimeglumine associated with significant improvement in

• detection/exclusion of pathologic features
• vessel anatomic delineation
• technical adequacy
• vessel visualization quality comparing predictive performance of MRA with gadobenate vs. gadopentetate in analysis of 127 segments (ranges for 3 readers)

• sensitivity 76%-83% vs. 61%-69%
• specificity 96% vs. 87%-92%
• positive predictive value 90%-91% vs. 71%-74%
• negative predictive value 89%-92% vs. 83%-86%

Computed tomography angiography (CTA)

CTA, duplex ultrasound, or MRA of the lower extremities for diagnosis of anatomic location and severity of stenosis for patients with symptomatic PAD in whom revascularization is considered

CTA or MRA useful to

• Develop individualized treatment plan, including assistance in selection of vascular access sites
• Identify significant lesions
• Determine feasibility of and modality for invasive treatment

Adverse effects of CTA may include ionizing radiation and adverse effects related to iodinated contrast administration (such as, contrast-induced nephropathy or rarely allergic reactions)

Based on systematic review40 of 20 studies using CTA for assessment of severity of lower extremity PAD in 957 patients

• studies compared multidetector CTA with intra-arterial catheter angiography or intra-arterial DSA
• 68% of patients had intermittent claudication

Methodological limitation included study sample sizes ranged from 16 to 279 patients and exclusion of 12 studies from meta-analysis due to insufficient data, and mostly

moderate-quality studies

CTA for detection of > 50% stenosis or occlusion associated with

• 95% sensitivity
• 96% specificity

CTA correctly identified occlusions in 94% segments, presence of > 50% stenosis in 87% segments, and absence of significant stenosis in 96% segments MDCT Approach to lower-extremity imaging General Acquisition Protocol for Lower-Extremity Arterial CTA

Low-osmolar nonionic contrast agents are most commonly used for CTA applications.41 Patients’ renal function should be assessed before administration of contrast and decisions regarding prophylactic medication use should be made if necessary.

The selection of the specific acquisition parameters of imaging depends on the employed scanner model, the patient’s body habitus, and the clinical question. The voltage is typically set at 120 kV, although 100 kV or even 80 kV provides acceptable images with significantly reduced radiation and can be employed in most individuals with PAD who are not obese.42 Tube current is usually 200 to 300 mA and can be adjusted upward if the patient is very large.

Breath-holding is required only for the chest and abdomen CTA acquisitions to reduce motion artifact. Although current generation scanners offer improved spatial

resolution, their increased coverage and rotation speeds pose the risk of “out-running” the bolus of contrast in CTA applications.

Accordingly, adjustments in both the pitch and the gantry rotation speed must be made to achieve a table translation speed of no more than 30 to 32 mm/s for CTA applications. In a 64-slice scanner, this usually is achieved by a reduction in t rot to 0.5 seconds and a decrease in pitch to less than or equal to 0.8. Patients are placed in a supine position on the scanner table in a feet-first orientation. The typical field-of- view (FOV) should extend from the diaphragm to the toes with an average scan length of 110 to 130 cm.

The scanning protocol begins with a scout image of the entire FOV followed by a test bolus or bolus triggering acquisition. When an automated bolus detection algorithm is used, the region of interest is set up in the aorta immediately below the level of the diaphragm.

A repetitive monitor acquisition (120 kV, 10 mA, 1-second interscan delay) is started 10 seconds after contrast injection begins. The actual peripheral CTA acquisition is then started when the contrast enhancement reaches a prespecified level (typically set between 150–200 HU). Breath-holding may be necessary for the more proximal abdominal station, but not for the distal stations. A second late acquisition of the calf vessels can be prescribed in the event of inadequate pedal opacification during the arterial phase.

For most CTA applications, 100 to 140 mL of contrast (with an iodine concentration between 350–370 mg/mL) is administered at a rate of 4 mL/s followed by a saline flush.43

Distal lower-extremity atherosclerotic disease. Three-dimensional, CTA volume- rendered image shows a segmental occlusion of the anterior tibial artery ( arrowith small bridging collateral arteries ( left panel ) and severe, three-vessel atherosclerotic disease of the leg ( right panel ). Axial CTA image (inset) shows calcification within the walls of the anterior tibial, posterior tibial, and peroneal arteries with poor luminal visualization.

A meta-analysis of CTA in PAD, published in 2007, using mostly four-slice systems reported a pooled sensitivity and specificity for detecting a stenosis of greater than 50% or segment of 92% (95% CI of 89%–95%) and 93% (95% CI of 91%–95%), respectively. The diagnostic performance of CTA in the infrapopliteal tract was lower but not significantly different from that in the aortoiliac and femoropopliteal levels.49 CTA findings clearly influence treatment decisions correctly in the vast majority of cases and are a definitive part of the imaging approach, especially when the decision to intervene percutaneously or surgically must be made.50,51

At least one study has compared the comparative effectiveness of various imaging approaches in PAD. The outcome measures included the clinical utility, functional patient outcomes, quality of life, and actual diagnostic and therapeutic costs related to the initial imaging test during 6 months of follow-up. Significantly higher confidence and less additional imaging were found for magnetic resonance angiography and CTA compared with duplex sonography at lower costs.52

Comparative effectiveness of noninvasive imaging tests

Based on systematic review53 of 113 studies

Accuracies for detecting stenosis > 50% in whole leg

• Contrast-enhanced MRA had 92%-99.5% sensitivity and 64%-99% specificity in 14 studies
• 2-D time-of-flight MRA had 79%-94% sensitivity and 74%-92% specificity in 11 studies
• 2-D phase-contrast MRA had 98% sensitivity and 74% specificity in 1 study
• CTA had 89%-99% sensitivity and 83%-97% specificity in 7 studies
• Duplex ultrasound had 80%-98% sensitivity and 89%-99% specificity in 28 studies
• Adverse events reported in 55 studies
• most common with MRA
• most severe adverse events (though rare) more common with CTA

This study concluded that duplex ultrasound may be most cost-effective test for whole leg, while two-dimensional (2-D) time-of-flight MRA may be most cost-effective preoperative strategy for localized segment of leg.

Based on randomized trial54352 patients (mean age 65 years) with PAD who needed imaging work-up and had ankle-brachial index (ABI) < 0.9 were randomized to contrast-enhanced MRA vs. duplex ultrasound and evaluated at 6 months

• use of MRA reduced number of additional imaging procedures by 42%
• diagnostic costs for MRA were higher
• Based on systematic review55 of 9 MRA studies and 18 duplex ultrasound studies that used conventional angiography as diagnostic standard
• MRA had 98% sensitivity, 96% specificity, positive likelihood ratio (LR) 26, and negative LR 0.03
• duplex ultrasound had 88% sensitivity, 95% specificity, positive LR 17, and negative LR 0.13

Based on randomized trial56 allocation concealment not stated 103 patients (mean age 72 years) having infra-inguinal bypass graft of great saphenous vein were randomized to preoperative ultrasound duplex vein mapping vs. no duplex vein mapping and followed for 12 months comparing duplex vein mapping vs. no duplex vein mapping

• major surgical site infections in 1.9% vs. 21.2% (p = 0.004, NNT 6)
• readmission due to surgical site infections in 3.9% vs. 19.2% (p = 0.028, NNT7)

This study concluded that preoperative duplex vein mapping may reduce infections and readmissions in patients having infrainguinal bypass graft

SUMMARY:

Age distribution: 2.5% were <40 years of age, 25% were in the age group of 41-50 years, 15% in the age group of 51-60 years,45% in 61-70 years age group, 12.5% in >70 years age group.

Gender distribution: 72.5% are male and 27.5% are female.

Grade of Claudication: Based on Grade of claudication, 40% had Grade 2 claudication, 47.5% had grade 3 claudication, 12.5% had Grade 4 claudication

Gangrene: 12.5% in the study had Gangrenous changes.

Personal History: In the study 60% are smokers and 30% are tobacco chewer.

In our study mostly the distal arteries were involved clinically as shown in the above graph in which 0 is absent; 1+ is diminished; 2+ is normal and 3+ is bounding respectively

Co-Morbidities: 27.5% are diabetic, 20% are HTN, 7.5% had IHD, 2.5% each had COPD, Acute MI, TB, Rheumatoid arthritis and Hepatitis B.

Diagnosis: 15% had TAO, 85% had Atherosclerosis

Colour doppler ultrasound versus MDCT:

In comparison of colour doppler ultrasound versus MDCT, there is statistically significant difference in the detection of the extent of segment involvement in SFA

In comparison of colour doppler ultrasound versus MDCT, there is statistically significant difference in the detection of the extent of segment involvement in DFA

colour doppler ultrasound and MDCT, there is significant difference in the detection of the extent of segment involvement in popliteal artery.

In comparison of colour doppler ultrasound versus MDCT, there is statistically extremely significant difference in the detection of the extent of segment involvement in ATA.

In comparison of colour doppler ultrasound versus MDCT, there is statistically extremely significant difference in the detection of the extent of segment involvement in PTA.

In comparison of colour doppler ultrasound versus MDCT, there is statistically extremely significant difference in the detection of the extent of segment involvement in peroneal artery.

In comparison of colour doppler ultrasound versus MDCT, there is statistically significant difference in the detection of the extent of segment involvement in ATA

MDCT is better than Doppler in detecting the length of stenosis in the arterial system.MDCT is better than Doppler in detecting the presence of thrombosis especially in the infra-popliteal segment.Even though MDCT is not statistically significant than Doppler in detecting the number of collateral segments , as the arterial tree is better delineated in MDCT , this modality is needed to be performed before any vascular intervention is planned.Doppler is also an effective tool which can detect the lesions to a comparable extent when no intervention is planned and only medical therapy is considered

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