Popliteal artery entrapment syndrome: morphological classification utilizing MR imaging

Objective To retrospectively analyze magnetic resonance (MR) findings in patients with popliteal arterial entrapment syndrome.Materials and methods This study was a retrospective MRI and CT scan review of 12 patients with 23 limbs with popliteal artery entrapment syndrome (PAES) treated over a 10-yr period. All 12 patients (23 limbs) were evaluated with MR and CT scan (11 patients—bilateral sides; one patient—unilateral side). All cases were classified as to various types of anomalous relationships between the popliteal artery and the neighboring muscles. The PAES was classified to gastrocnemius medial head and lateral head anomaly. Gastrocnemius medial head anomaly was classified according to the classification made by Whelan and Rich, from type 1 to type 6 [12, 13]. Gastrocnemius lateral head anomaly was defined as popliteal artery entrapment due to medially inserted gastrocnemius lateral head or aberrant accessory head of gastrocnemius lateral head.Results The gastrocnemius medial head anomaly was found in 14 limbs (14/23). The classic type 1 was found in none, type 2 in five patients (six limbs), type 3 in four patients (five limbs), type 4 in none, type 5 in one patient (one limb) and type 6 in one patient (two limbs). The uncommon type, i.e. lateral head of gastrocnemius anomaly, was found in five patients (eight limbs).Conclusion The gastrocnemius medial head anomaly was the cause of PAES, and PAES was classified by medial head anomaly. However the gastrocnemius lateral head anomaly was also the cause of PAES, and most cases of gastrocnemius lateral head anomaliy showed aberrant accessory slip which entrapped the popliteal artery and vein.     

Popliteal artery entrapment syndrome evaluation with multislice CT angiography

Purpose

The purpose of this study is to evaluate the use of multislice computed tomography (MCT), Doppler US, and angiography in the diagnosis of popliteal artery entrapment syndrome.

Patients and methods

In a prospective study of 26 patients referred to Doppler ultrasound examination with suspected popliteal artery entrapment syndrome, we have made Doppler study of the popliteal artery of the diseased limb using 7–10 MHz probe. Additional multislice CT angiography after bolus injection of non-ionic contrast medium (Ultravist), axial transverse sections and multiplanar reformation reconstruction images were analyzed. Conventional angiography of the diseased limb was performed with the use of pigtail catheter and injection of 60 cc Ultravist.

Results

On 22 of 26 patients, the Doppler study revealed damped flow, biphasic waves and a dramatic decrease in peak velocity. All these signs appeared in the Doppler study of popliteal artery while retaining normal flow and waves in distal tibial vessels.When 26 patients were examined, the conventional angiography revealed sudden attenuated and decreased caliber of popliteal artery with retained average caliber of the distal run-off vessels without showing the surrounding structures.When 26 patients were examined, the CT angiography revealed decreased caliber of popliteal artery, verified the exact diameter of popliteal artery and gave an accurate idea about the wall of the vessels and the surrounding soft tissue structures. These last benefits enable us to differentiate between organic and functional causes of popliteal artery entrapment syndrome.

Conclusion

In conclusion, popliteal artery entrapment syndrome can be diagnosed with the use of multislice CT which is as efficient as conventional angiography. However, multislice CT provides detailed information on the wall, diameter of the artery and relation of the artery to adjacent structures by a non-invasive technique.     

Isolated popliteal vein entrapment

We present two cases of isolated popliteal vein entrapment caused by the lateral head of the gastrocnemius muscle confirmed by both venography and magnetic resonance imaging of the knee.     

Craniocervical artery dissection: MR imaging and MR angiographic findings

Dissection of the carotid and vertebral arteries is a not so uncommon cause of stroke and has to be considered as a differential diagnosis especially in younger patients. Therapeutic and prognostic implications are different from those in extracranial atherosclerotic disease. Dissection results from hemorrhage into the vessel wall usually between the layers of the media. Digital subtraction angiography (DSA) depicts the resulting luminal compromise that may reveal some typical, but not specific, findings. The same is true for non-invasive angiographic techniques such as time-of-flight magnetic resonance angiography (MRA) and computed tomography angiography (CTA), which have shown accurate results compared with DSA. The main advantage of these techniques is the direct visualization of the vessel wall confirming the intramural hematoma. This is achieved best with MR imaging due to the high signal of blood degradation products on T1- and T2-weighted images. Therefore, MRI in combination with MRA is presently the method of choice for initial diagnosis and follow-up of craniocervical artery dissection (CCAD). In some questionable cases, CTA is a non-invasive alternative that is independent of flow phenomena. Received: 4 May 1998; Revision received: 8 September 1998; Accepted: 10 November 1998     

Bilateral popliteal artery entrapment syndrome: reemphasis on reading axial tomograms

A 33-year-old man with bilateral popliteal artery entrapment syndrome (PAES) presented with right calf claudication. He underwent radiological studies including conventional arteriography, multidetector row CT (MDCT), and magnetic resonance imaging (MRI) of the lower extremities. He had been fine since birth and athletic in his school days. Axial tomographic images by MDCT and MRI at the popliteal fossa bilaterally showed an anomalous medial head of the gastrocnemius muscle between the popliteal artery and vein, resulting in right popliteal artery occlusion and leading to the diagnosis of bilateral PAES type II. MDCT or MR facilitates noninvasive computer-aided arteriography and is often utilized for screening patients with claudication for peripheral arterial diseases. However, axial tomograms are more essential for confirming PAES than arteriography, and radiologists should continue to look for possible abnormalities on popliteal fossa tomograms because early diagnosis of PAES allows better choices and outcomes of treatment.     

Bilateral popliteal entrapment syndrome in a young athlete diagnosed with ultrasound

Popliteal artery entrapment syndrome (PAES) occurs when the popliteal artery is compressed by abnormally developed or hypertrophied muscles adjacent to the popliteal fossa. When symptomatic, it most frequently presents with leg cramping while walking or running. We describe the case of an 18-year-old female runner presenting with claudication and exercise intolerance. After MRI was non-diagnostic, diagnostic ultrasound demonstrated that she had functional (Type VI) PAES. She subsequently underwent popliteal artery release surgery. Type VI PAES should be considered in young, healthy patients who present with claudication, particularly athletes.     

飞行员腘动脉压迫综合征一例并文献回顾

目的 探讨腘动脉压迫综合征的临床特征及飞行人员的健康鉴定原则. 方法 分析1例飞行员腘动脉压迫综合征的临床资料,并复习国内外相关文献16篇. 结果 患者以间歇性跛行为首发症状,下肢血管多普勒彩色超声及动脉造影检查发现右侧腘动脉闭塞,下肢血管及腘窝核磁检查提示右侧腓肠肌内侧头起始位置升高,使腘动脉位于股骨内上髁与腓肠肌内侧头之间的狭窄缝隙内. 结论 腘动脉压迫综合征是一种罕见的血管外科疾病,动脉造影、血管超声、CT及MRI对诊断及鉴别诊断具有重要价值,及早诊断有利于指导手术治疗方案和改善患者预后.飞行人员患腘动脉压迫综合征,应个别评定飞行结论 .     

Pancreatic adenocarcinoma: combination of MR imaging, MR angiography and MR cholangiopancreatography for the diagnosis and assessment of resectability

The purpose of this study was to determine the possibility of integrating MR cholangiopancreatography (MRCP) and MR angiography (MRA) to conventional MR images in the diagnosis and assessment of resectability of pancreatic adenocarcinoma. Twenty-three patients with pancreatic adenocarcinoma were prospectively examined with MR. Conventional MR images were acquired in all patients. Three-dimensional MRCP and MRA images were acquired in all patients with suspected biliary and vascular involvement. Acquisition time was less than 45 min in all cases. Images were independently evaluated by two radiologists, with final reading decided by consensus among readers. Diagnosis was confirmed with surgery in 16 patients and with percutaneous biopsy in 7. Concordance among readers was high with a kappa value of 0.83. Pancreatic adenocarcinoma was observed in all patients. Correct assessment of unresectability due to vascular involvement was found in 22 of 23 patients. Biliary obstruction was evident in 13 patients, involving the biliary and pancreatic ducts in 9 and the biliary ducts only in 4. Technical advances permit extensive use of MRI in the evaluation of abdominal pathologies. The combination of MR imaging, MRCP, and MRA can provide sufficient information for the diagnosis and assessment of resectability of pancreatic adenocarcinoma, which otherwise would require three different exams. Received 22 August 1996; Revision received 3 June 1997; Accepted 19 August 1997     

Contrast-enhanced three-dimensional MR angiography in the assessment of subclavian artery diseases

The purpose of this prospective study was to determine the potential diagnostic value of 3D breath-hold contrast-enhanced MRA (CEMRA) in the evaluation of subclavian artery pathology, and to compare CEMRA and digital subtraction angiography (DSA) findings. The study group included 50 patients with suspicion of subclavian artery pathology: 40 suspected steno-occlusive disease and 10 different vascular anomalies. The MRA examinations were performed on a 1.5-T system using fast 3D sequences. A fixed dose of 40 ml Gd-DTPA was administered at 2 ml/s after previous bolus tracking. Images were analyzed to assess: subclavian depiction; luminal changes; collateral branches; and feeders of arterial venous malformations (AVM). A multireader blinded fashion was used. The CEMRA revealed an optimal agreement with DSA findings in the different types of diseases. Sensitivity and specificity were 90 and 95 %, respectively, in detecting steno-occlusive disease (including functional and arteritic stenoses), and 100 and 100 %, respectively, in cases of vascular anomalies (dilation, kinking, anomalous origin and AVM). Contrast-enhanced MRA can be proposed as a non-invasive, robust technique for imaging subclavian pathologies with high diagnostic performance. Received: 18 May 1999; Revised: 5 January 2000; Accepted: 27 March 2000     

Coarctation of the aorta: comparison of aortic dimensions between conventional MR imaging, 3D MR angiography,and conventional angiography

Magnetic resonance angiography is increasingly used as a non-invasive method in the evaluation of coarctation of the aorta. The aim of this study was to compare aortic dimensions calculated by MR angiography and those obtained by more conventional MR sequences and conventional angiography. Twenty-six consecutive patients with coarctation underwent three-dimensional MR angiography. Two independent observers retrospectively evaluated three aortic segments, site of coarctation, presence of aneurysm and existence of collateral circulation. Three aortic segments were also compared with those obtained on classical MR sequences and conventional angiography. The MR angiography was successfully performed in all showing 1 aneurysm and collateral circulation in 8 patients. Almost perfect intraobserver ( r(2)>0.91) and excellent interobserver ( r(2)>0.80) reliabilities were obtained for each aortic segment no matter which MR sequence was employed. Similarly, mainly excellent ( r(2)>0.80) concordance analysis was observed between MR angiography measurements and those calculated by either spin-echo/gradient-echo sequences or conventional angiography. This study demonstrates that MR angiography is a fast, accurate and reproducible method in the evaluation of coarctation of the aorta. It provides excellent anatomic information and reliably detects collateral vessels. Magnetic resonance angiography could probably replace the conventional angiography and will provide an additional diagnostic value in combination with turbo spin-echo sequence.     

Stress MR imaging for evaluation of popliteal artery entrapment

The popliteal artery entrapment (PAE) syndrome has been recognized as a cause of arterial occlusion in young people. It is the result of an anomaly of the relationship between the popliteal artery and the gastrocnemius muscle. Eight young healthy volunteers (16 legs) and six patients (10 legs) with suspected PAE underwent magnetic resonance (MR) imaging. Gradient-echo images were obtained in axial planes with the leg at rest and during active plantar flexion against resistance. Imaging at rest allowed identification of PAE signs in only one leg, which had an anomalous medial course of the popliteal artery. In the other cases, only the stress technique was able to show signal loss in the popliteal artery due to muscular compression (two legs) or the presence of accessory muscle slip around the vessel (two legs), as confirmed at surgery. MR imaging is therefore a useful technique for the diagnosis of PAE because of its capability of combining information obtainable with other modalities.     

MR imaging and MR angiography of persistent trigeminal artery and its variant

Six patients with persistent trigeminal artery (PTA) and one patient with its variant (PTAV) were studied using a 1.0-T magnetic resonance unit. With both magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), four of the six PTAs were detected as abnormal connecting arteries between the cavernous internal carotids and the basilar arteries. The remaining two PTAs and one PTAV were not detected using MRI, but were imaged by MRA. It was concluded that relatively large PTAs can be detected using MRI, but small PTAs and PTAVs may be missed using MRI.     

Magnetic resonance imaging of popliteal artery pathologies

This paper illustrates examples of popliteal artery pathologies imaged with contrast enhanced magnetic resonance angiography (CE-MRA) and magnetic resonance imaging (MRI) at a single tertiary referral centre. Popliteal artery pathologies were identified in 1710 patients referred over a 6-year period with symptoms suggesting lower limb arterial occlusive disease. Common pathologies such as atherosclerotic occlusive disease, thromboemboli and aneurysm disease are discussed as well as unusual pathologies such as cystic adventitial disease, mycotic aneurysm and arterial entrapment. The combination of CE-MRA and the excellent soft tissue resolution of MRI allow detailed evaluation of arterial and peri-arterial pathologies, and facilitate appropriate management decisions.     

MR imaging: acronyms and clinical applications

The intention of this article is to provide an overview of all MR imaging techniques that are accessible on most of commercially available scanners and have the potential to be used in routine clinical applications. The techniques implemented by the major vendors are briefly explained, including a comparison of the commonly used acronyms. A classification scheme is introduced which provides a reasonable illustration of similarities and differences between various techniques. The imaging techniques are divided into two main groups, the spin-echo and gradient-echo sequences. Within each group is the basic sequence, those which require a preparation of the magnetization, those which use multiple echoes to fill the k-space and those which are performed in a single shot. For each technique the typical clinical applications are listed or the potential applications which have been published. Received: 18 August 1998; Revision received: 3 November 1998; Accepted: 4 November 1998     

Quantification of blood flow in the middle cerebral artery with phase-contrast MR imaging

The aim of this study was to assess blood flow in the middle cerebral artery (MCA) according to age, gender, and side. Eighty-eight subjects without carotid obstruction were measured for mean velocity, vessel area, and volume flow rates of both MCA with phase-contrast MR. A high-resolution sequence with a matrix of 300 × 512 and a double oblique localizing strategy was used for measurement. A mean velocity of 33 ± 6.8 cm/s, a mean vessel area of 6.2 ± 1.2 mm² and a mean flow rate of 121 ± 28 ml/min were measured in the MCA. Lower volume flow rates were seen in subjects aged over 50 years (p < 0.01). When comparing women with men, a lower vessel area (p < 0.05) of the MCA was counterbalanced by a higher velocity, resulting in no significant difference of the volume flow rate. No difference occurred between the right and the left side. Flow reduction occurs in the elderly. A lower vessel area of the MCA in women is compensated by a higher velocity. Received: 3 September 1999; Revised: 17 January 2000; Accepted: 23 February 2000     

Intraindividual comparison of contrast-enhanced electron-beam computed tomography and navigator-echo-based magnetic resonance imaging for noninvasive coronary artery angiography

The aim of this study was to compare contrast-enhanced electron-beam computed tomography (EBCT) and navigator-echo-based MRI of the coronary arteries in the same patient population. Both methods were assessed for visualization of the coronary arteries and their diagnostic accuracy in identifying significant coronary artery stenoses compared with conventional coronary angiography. Twenty patients with known coronary artery disease were examined with both contrast-enhanced EBCT and a respiratory-gated MRI sequence. A grading system was used to evaluate the image quality. Sensitivity and specificity for the detection of significant coronary artery stenoses was evaluated compared with conventional coronary angiography. With EBCT, 89% of the main coronary arteries could be completely visualised in the proximal and middle segments; with MRI, 83% were visualised. With EBCT the sensitivities for identifying significant (>/=50%) stenoses in proximal and middle vessel segments were 75% in the main stem, 88% in the left anterior descending coronary artery, 75% in the left circumflex coronary artery, and 90% in the right coronary artery. Respective sensitivities for MRI angiograms were 75, 82, 75 and 80%. With both modalities a sufficient image quality of the main coronary arteries can be obtained in most cases. The diagnostic capability for detecting significant stenoses is comparable for both methods.     

Multidetector CT angiography in spontaneous popliteal artery dissection

Primary dissection of the femoropopliteal or popliteal arteries is rare in the absence of involvement of the aorta or aneurysmal arterial changes. In this report, we present multidetector CT angiography findings of a case of a spontaneous nonaneurysmal dissection limited to the left popliteal artery in an otherwise healthy 40-year-old woman.     

Time-resolved contrast-enhanced 3D MR angiography

An MR angiographic technique, referred to as 3D TRICKS (3D time-resolved imaging of contrast kinetics) has been developed. This technique combines and extends to 3D imaging several previously published elements. These elements include an increased sampling rate for lower spatial frequencies, temporal interpolation of k-space views, and zero-filling in the slice-encoding dimension. When appropriately combined, these elements permit reconstruction of a series of 3D image sets having an effective temporal frame rate of one volume every 2-6 s. Acquiring a temporal series of images offers advantages over the current contrast-enhanced 3D MRA techniques in that it i) increases the likelihood that an arterial-only 3D image set will be obtained, ii) permits the passage of the contrast agent to be observed, and iii) allows temporal-processing techniques to be applied to yield additional information, or improve image quality.     

MR imaging and angiography in tuberculous meningitis

MRI was performed on 26 patients with tuberculous meningitis, with particular reference to document the cranial nerve abnormalitics. MR angiography (MRA) was performed in 20 of the patients. Meningeal enhancement in the basal cisterns or over the convexity of brain was seen in all patients; two show ependymal enhancement. Tuberculomas, single (3), multiple (12) or miliary (2) were detected in 17 patients. Of the 9 patients with cranial nerve palsies, 7 showed contrast enhancement with or without thickening of the involved nerve. Abnormality signal intensity of the involved nerve was seen on proton density and T₂-weighted images in one of these patients. MRA revealed focal arterial narrowing in 10 patients, the vessels commonly affected being the terminal segment of the internal carotid artery and the proximal segments of the middle and anterior cerebral arteries. One patient also had a small aneurysm of the proximal middle cerebral artery. Infarcts, haemorrhagic (8) or bland (6), were detected in 14 patients; most were the basal ganglia and internal capsules, large middle or anterior cerebral arterial territory infarcts being seen in only two cases.