Noninvasive Imaging Techniques In The Diagnosis And Treatment Of Popliteal Vascular Entrapment Syndrome

Purpose:To evaluate the potential role of noninvasive imaging techniques such as Doppler sonography, CT angiography (CTA), MRI and MR angiography in the diagnosis and treatment of popliteal vascular entrapment syndrome(PVES).Materials and methods:Twenty-six patients (36 limbs) who underwent surgical treatment for PVES were evaluated retrospectively. Eighteen of the study patients were male and eight were female. The ages of the patients ranged from 9 to 64 years (mean,27.2 years). Ten patients were affected bilaterally. Doppler sonography, CT angiography and MRI were preformed in all of the cases. Digital subtraction angiography (DSA) were preformed in 18 patients and MRA in 13 patients. Both DSA and MRA were performed bilaterally in ten patients. All exams were considered technically adequate.DSA was performed using the Angiostar Plus unit (Siemens Medical Solutions). The angiographic evaluation included biplanar imaging with the foot in neutral, active plantar flexion, and dorsiflexion positions. Digital subtraction angiographic images of the foot in a neutral position were compared with the DSA images during provocative maneuvers for assessment of compression of the popliteal artery. Both popliteal arteries were examined to determine whether the anomaly was bilateral. With regard to DSA findings, we examined to determine the presence or absence of stenosis, thrombosis, aneurysm, abnormal course of the popliteal artery, and the presence of collateral arteries. The position of popliteal artery was classified as medially displaced, normal, and laterally displaced.The ultrasonographic findings of all cases were reviewed. The popliteal vascular were assessed. Doppler scan confirm entrapment by revealing an artery course deviation or an abnormal anatomical element between the artery and the popliteal vein, increasing the distance that separates the two vessels. when the popliteal artery is not occluded, provocative maneuvers were used. Transverse sections of CTA were reconstructed for both extremities on a workstation. For each patient, multiplanar reconstruction (MPR), maximum intensity projection (MIP), and volume rendering (VR) were used. MIP reconstruction were used in all MRA examinations. Imaging findings were analyzed according to the most widely accepted classification made by Love and Whelan and Rich et al, from typeâ… to typeâ…¥. The Doppler sonography, CTA, and MR images were evaluated separately to classify each case. The soft-tissue anatomy and vascular structures around the knee were assessed on the CTA and MRI images. MPR, MIP, and VR were used to assess the vascular tree for a more detailed analysis.1. Operative result was performed as a standard reference in all cases. To investigate the diagnostic value of doppler sonograpy, CTA and MRI in PVES and evaluate the clinical application in classification and the relationship between the popliteal vessels and adjacent musculotendinous structures of PVES.2. The degree of stenosis in a popliteal artery segment was classified as absent, mildly stenotic (1%-49% luminal narrowing), medium stenotic (50%-74%), severely stenotic (75%-99% luminal narrowing), or total occlusion. The degree of the popliteal artery stenosis in DSA, CTA and MRA images were evaluated with five-grading system. DSA in neutral position was performed as a standard reference. The sensitivity, specificity, and accuracy were calculated for the demonstration of stenosis degrees, which were showed by CTA and MRA. 3. Operative result was performed as a standard reference. To compare the merit and pitfall of doppler sonography, CTA and MRI combined with MRA in patients with PVES.Results:All 26 patients (36 limbs) with PVES were treated surgically.31 cases had gastrocnemius medial head anomalies. There were 8 cases of typeâ… entrapment,15 cases of typeâ…¡, and 5 cases of typeâ…¢,1 case of typeâ…£and 2 cases of typeâ…¥. There were no cases of type V.5 cases had the lateral head of the gastrocnemius muscle anomalies. Aberrant slips of the lateral head of the gastrocnemius muscle had caused PVES in all 5 cases.Doppler scan confirm entrapment by revealing an artery course deviation or an abnormal anatomical element between the artery and the popliteal vein in 15 cases. Stenosis or occlusion of popliteal artery in 23 cases and aneurysmal formation in 4 cases. The pulses of dorsal pedis artery disappeared in 8 cases. Deep vein thrombosis and chronic venous insufficiency were diagnosed in 3 cases. Provocative maneuvers were positive in 12 cases.15 cases (41.7%) were confirmed in doppler sonography. Doubtful diagnosis in 10 cases (27.8%) and missed diagnosis (30.5%) in 11 cases.DSA showed occlusion of the popliteal artery in 9 limbs. Distal popliteal artery segments were perfused by abundant genicular collateral vessels in the 9 limbs. Medial deviation of the popliteal artery was noted in 5 limbs. The popliteal artery is normal, mildly stenotic, medium stenotic, severely stenotic in 20,1,2,4 respectively. Medial displace of popliteal artery is in 5 cases. Aneurysmal formation were noted in 2 cases. Provocative maneuvers by DSA were positive in 7 cases.14 cases (66.7%) were confirmed in DSA and missed diagnosis (33.3%) in 7 cases.All axial CTA images showed soft-tissue structures and the vasculature of the popliteal fossa sufficiently. Evaluation of the axial images showed various degrees of abnormal intercondylar insertion of the medial head of the gastrocnemius muscle laterally, medial displacement displacement of the popliteal artery, and segmental occlusion of the popliteal artery. VR and MIP reconstructions showed genicular collaterals supplying the distal popliteal arterial segments. Each case was classified on the basis of the CTA findings. Classifications based on CTA findings were consistent with these based on intraoperative photography. The popliteal artery is normal, mildly stenotic, medium stenotic, severely stenotic and occlusion in 19,2,2,4,9 respectively on CTA findings. Medial displace and aneurysm of popliteal artery is in 8 and 4 cases. Medial displace and aneurysm of popliteal artery was not showed in 3 and 2 cases by DSA findings. Using DSA in neutral position as the standard reference, the sensitivity, specificity, and accuracy of CTA for the demonstration of stenosis degrees of popliteal artery were 100%,95% and 97.2%. With the regard the detection of segments that had more than moderate stenosis, the sensitivity, specificity, and accuracy of CTA were 100%,100%,100%.MRI provided high-resolution images of the anatomy of the popliteal fossa and anomalous structures and confirmed the diagnosis of PVES in all 36 limbs. Characterization and classification based on MRI findings were consistent with intraoperative photography. Using DSA as the standard reference, the sensitivity, specificity, and accuracy of CTA for the demonstration of stenosis degrees of popliteal artery were 100%,100% and 100%. On MRI findings regarding the deviation of popliteal artery, the site and origin of popliteal artery stenoses, occlusion, and collateral circulation were consistent with DSA in neutral position. There were no significant differences between the length and the location of stenoses, occluded segments, and collateral vessels identified on CTA compared with MRA findings.Conclusion:1. PVES is an uncommon congenital anomaly affecting young adults who present with symptoms of calf claudication. Because PVES is a progressive disease that can create serious complication, accurate and prompt diagnosis of PVES is crucial.2. DSA is the classical screening and diagnostic tool in PVES. DSA can clearly show the anatomic features of a vascular lesion. But DSA is invasive and DSA findings of PVES are nonspecific in most cases and may not identify the underlying cause of the occlusion and thrombosis. Although DSA may have a role in the evaluation of patients with claudication, it is not sufficient to render a diagnosis of PAES, especially in cases of arterial occlusion. 3. Doppler sonography is a quick, and noninvasive screening technique for the early diagnosis of PVES. Doppler sonography is most useful in the diagnosis of PVES when the popliteal artery is patent. Provocative maneuvers can aid to diagnose PVES. However, false-positive results are also common. Furthermore, Doppler sonography is not able to image soft-tissue structures and missed diagnosis may happen.4. CTA is a novel noninvasive diagnostic approach for PVES given that it rapidly provides high spatial resolution images of a large anatomic range. Several postprocessing technologies, such as MPR, MIP, and VR, can be used to provide 3D reconstructions and reveal vascular abnormalities. Computed tomographic angiography provides optimal visualization of the popliteal artery and the surrounding structures and seem to be of greater utility than DSA in the diagnosis and evaluation of PVES.5. MRI is noninvasive, does not expose the patient to radiation, and provides surgically relevant anatomic detail and high soft-tissue resolution. MRI reveal detailed anatomic information of the popliteal vascular and the adjacent structures. MRI combined with MRA is the most effective tool in the diagnosis, characterization, and classification of PVES, allowing a better choice of treatment.