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British Journal of Radiology 75 (2002),578-583 © 2002 The British Institute of Radiology

Full Paper

Evaluation of chronic venous disease in the lower limbs: comparison of five diagnostic methods

M Mantoni, MD, DMSc 1 L Larsen, MD 3 J O Lund, MD 2 L Henriksen, RN 4 T Karlsmark, MD, DMSc 5 C Strandberg, MD 1 J Ogstrup, RN 2 S Ribel-Madsen 6 F Gottrup, MD, DMSc 5 and L Danielsen, MD, MSc 4

Departments of 1 Radiology and Ultrasound and 2 Clinical Physiology/Nuclear Medicine, Gentofte Hospital, DK-2900, Denmark and Departments of 3 Radiology and 4 Dermatology and 5 Copenhagen Wound Healing Center, Bispebjerg Hospital, University of Copenhagen and 6 Trier Research Laboratory, Frederiksberg, Denmark


   Abstract
Top
 Abstract
Introduction
 Patients and methods
 Results
 Discussion
 References
 
To compare the usefulness of five diagnostic methods in ensuring deep vein patency, and in demonstrating site(s) of incompetence, 39 patients with clinical signs of chronic venous disease of a leg were included in a study of deep, superficial and perforator veins using triplex ultrasound (TUS), ascending phlebography (AP), descending phlebography (DP), continuous wave Doppler (CWD) and ambulatory strain gauge plethysmography (ASGP). One patient withdrew from the study. It was not possible to use all five methods in all 38 cases, and the methods could only be used partly in some cases. TUS, which allows anatomical, morphological and functional evaluation of the venous system, was chosen as the reference method. There was poor agreement between TUS and AP, and no agreement between TUS and ASGP, in the diagnosis of venous occlusion. AP demonstrated reflux (abnormal valves) in 7 of 22 patients with competent veins at TUS, and missed reflux in 13 of 15 patients with incompetent veins. Similarly, CWD overdiagnosed reflux in 13 of 20 patients and missed the reflux in 3 of 14 patients. DP was only technically possible in 11 patients. ASGP diagnosed venous reflux in all patients with incompetent deep veins, but also indicated deep vein or perforator vein reflux in all but one patient with competent deep veins. The agreement between TUS and the other methods in evaluating reflux in the deep veins was not better than that expected to occur by chance, Cohen's kappa being less that 0.20. It is concluded that AP, CWD and ASGP are of little value in the work-up of patients with deep venous insufficiency.


   Introduction
Top
 Abstract
 Introduction
Patients and methods
 Results
 Discussion
 References
 
The risk of developing a venous leg ulcer is directly correlated to an increased ambulatory venous pressure [1], which in turn is induced by insufficiency of superficial, perforator and/or deep veins. In some cases, surgery on superficial and perforator veins has been without effect on venous insufficiency, ulcer healing or relapse [2–5]. Thus, evaluation of the deep veins is of importance when vein surgery is considered, but it is only in recent years that deep veins have been evaluated for insufficiency prior to surgery.

The literature on chronic venous insufficiency is extensive and complex. International standards for disease classification have been widely employed [6].

In the present study, ascending phlebography (AP) has been used primarily to study topography and morphology of the venous system [7], while descending phlebography (DP), continuous-wave Doppler (CWD) and ambulatory strain gauge plethysmography (ASGP) have been used for functional evaluation [8, 9]. Triplex ultrasound (TUS) combines B-mode duplex and color Doppler imaging and is used to evaluate both morphology and competence of the venous system [10–12]. The purpose of this study was to compare the diagnostic efficacy of these five techniques, both in ensuring deep vein patency and in demonstrating the site(s) of incompetence, in patients with clinical signs of venous insufficiency.


   Patients and methods
Top
 Abstract
 Introduction
 Patients and methods
Results
 Discussion
 References
 
Patients
39 patients with clinical signs of chronic venous disease of a leg including lipodermatosclerosis with or without an ulcer, clinical class 4–6 according to the Clinical signs, Etiology, Anatomic distribution and Pathophysiology (CEAP) classification [6], and a systolic blood pressure of the first toe >60 mm Hg [13], were included. One patient withdrew from the study after the first examination (CWD). The median age of the remaining 38 patients was 67 years (range 28–86 years). Patients comprised 15 females and 23 males. At entry into the study 21 patients had an ulcer, 13 patients had a history of a previous ulcer while 4 patients had no ulcer history. Previous vein surgery had been performed on 17 legs (median 1 operation, range 0–13). 14 patients (36%) reported previous deep vein thrombosis (DVT). None of the patients had a previously known valvular aplasia.

Methods
All patients were examined for venous sequelae after DVT and venous valve incompetence. Only one leg, "the ulcer leg" when actual or previous ulcer was recorded, was examined. Examiners using a particular method were unaware of the results of the other examinations.

CWD was performed by two authors (LH or TK) by means of an Super Duplex Huntleigh Doppler unit with an 8 MHz probe (Huntleigh Technology, Cardiff, UK), according to standard procedures [14]. The deep veins (femoral, popliteal and posterior tibial) were examined for spontaneous flow and reflux during the following manouvres: Valsalva, compression of the long saphenous vein, compression of the calf and a tourniquet on the thigh occluding the long saphenous vein, and rhythmic compression of the calf and foot. The superficial veins (long and short saphenous veins, varicose veins, sapheno-femoral junction and sapheno-popliteal junction) were examined for reflux by rhythmic finger compression of the calf or gaiter area. The perforator veins (Cockett's perforators) were examined for reflux by compression of the calf below the probe, with a tourniquet above and below the examined area.

AP was performed by one author (LL) as recommended by Thomas [7]. A tourniquet was placed above the ankle or around the forefoot, and another above the knee. A tape measure was attached to the leg. The patient was elevated in 60–70° anti-Trendelenburg position without bearing weight on the examined leg, and 50–150 ml Omnipaque® (Nycamed Amersham, Oslo, Norway) (240 mg I ml-1) was injected into a vein on the forefoot under fluoroscopic control. The study was observed for possible obstruction signs such as occluded venous channels, irregular lumen and reduplication. The veins were observed for missing or abnormal valves and the perforator veins were observed for insufficiency. Criteria for abnormality of a deep vein as described by Stacey et al [3] and Thomas [7] were slightly modified and used for evaluation; absent or abnormal valves, irregular outline of the vein, lack of visualization with or without collaterals bypassing.

DP was performed by one author (LL), with the patient in the erect position. An 18 G needle (Secalon®; Beckton Dickenson, Singapore) was inserted into the common femoral vein. 20 ml of Omnipaque® (240 mg I ml-1), were injected during a Valsalva manouvre. Contrast injection was observed fluoroscopically and recorded on video tape or plain radiography. If contrast was observed at the knee level, another injection followed with radiographs taken below the knee. The DP was studied for reflux and classified using a 0 to IV grading [15].

TUS was performed by two authors (MM and CS), with a Hitachi EUB 515A ultrasound unit (Hitachi Medical Corp., Tokyo, Japan) with 5 MHz and 7.5 MHz transducers. The study included examination for (1) occlusion of the deep veins and other possible sequelae after thrombosis in the deep and superficial veins, (2) reflux in the deep and superficial veins, and (3) insufficient perforators of the calf.

A scan for sequelae of DVT was considered negative if the compression test was normal [10], and if spontaneous flow and normal augmentation was present [12]. An examination was considered to show sequelae after DVT if one or more of the following signs were observed: visualization of residual thrombus, thickened recanalized veins with lack of or incomplete compressibility, collateral veins together with occlusion or residual venous obstruction [12].

Quantitative evaluation of venous valvular reflux was performed as described by Van Bemmelen et al [16], with the patient in a standing position bearing weight on the contralateral leg. For evaluation of the common and superficial femoral vein and the sapheno-femoral junction, a 24 cm thigh cuff was inflated to prevent flow within the veins, usually to approximately 80 mm Hg for approximately 3 s, and then rapidly deflated. Similarly, for examination of the popliteal vein and the sapheno-popliteal junction a 12 cm cuff was applied below the knee. Spectral analysis was recorded to quantify the amount of reflux (Figure 1Go). The upper limit for the duration of retrograde flow was 0.5 s, which is the time taken for the normal venous valve to close [16]. Reflux in the superficial veins was evaluated when reflux was observed in the sapheno-femoral junction or in the sapheno-popliteal junction.



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  		Figure 1. Triplex ultrasound examination of popliteal vein. Doppler sampling gate in popliteal vein. Calf compression results in antegrade flow (spectral curve below baseline); when compression is released spectral curve shows reflux (retrograde flow above baseline) for 2 s until the next compression.

 
The lower leg was examined for incompetent perforating veins, with the patient sitting with the leg in a dependent position. Tourniquets were applied on the forefoot and below the knee to prevent flow in the superficial veins. The forefoot was compressed manually while scanning the medial aspect of the calf for reversed flow of the perforators. Direction of blood flow could be determined by TUS. If the patient had an ulcer on the lateral aspect of the leg, that side of the calf was examined as well.

Plethysmography was performed by two authors (JOL and JO). ASGP [9] was performed with the strain gauge applied to the lower calf just proximal to the malleolus. With the patient in the standing position, changes in calf volume were recorded during venous emptying accomplished by standardized knee bends followed by recording of the refilling phase. The expelled volume (EV) and refilling time (RT) were measured. The measurement was performed in duplicate and further repeated with a below knee compression cuff inflated to 70 mm Hg. EV is a measure of the venous pump function and depends on patency of veins and normal venous function. Normal values are >0.7 ml x 100 ml-1. Reduced RT (RT<42 s) in the first part of the examination indicates venous reflux in the superficial and/or deep veins or incompetent perforating veins (Figure 2Go). Normalization of RT after application of a compression cuff indicates that venous incompetence is located solely in the superficial veins, whereas unchanged RT indicates deep vein or perforator vein insufficiency in the lower part of the leg.



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  		Figure 2. Ambulatory strain gauge plethysmography. The unbroken line illustrates the volume changes in an extremity with an abnormal short refilling time (RT) (8 s) indicating venous reflux or incompetent perforating veins. For comparison the broken line shows slow refilling of the venous system in an extremity with normal, competent veins. EV, expelled volume.

 
TUS was used as the reference method. For evaluation of patency of the deep veins, AP and ASGP (expelled volume) were compared with TUS. When evaluating for venous reflux, AP, CWD, DP and ASGP (refilling time) were compared with TUS.

Agreement between the diagnostic methods was analysed by calculation of Cohen's kappa coefficient. This statistical method is a standard procedure in reliability testing and involves calculation of the difference between the observed proportion of cases in which outcomes agree and the proportion of agreement expected by chance, and normalization of the difference by dividing it by the maximum difference possible for the marginal totals. A kappa value of 1 corresponds to perfect agreement, and a value of zero indicates that agreement is no better than chance. The null hypothesis that kappa is zero was tested on the basis of the ratio of kappa to its standard error. Estimates of the "sensitivity" and "specificity" of methods in comparison with TUS, the results of which were considered true, were calculated from the observed frequencies.

This study was approved by the local Research Ethics Committee.


   Results
Top
 Abstract
 Introduction
 Patients and methods
 Results
Discussion
 References
 
It was not possible to use all five methods in all cases, and methods could only be partly used in some cases. At TUS, limitations of the calf vein examination were found in three patients with large ulcers. With AP, the examination was deemed insufficient in 12 legs, where all the three pairs of calf veins were not visualized. Two patients could not perform the knee bending necessary for the ASGP, and in 15 patients CWD of calf veins was inconclusive. DP was only technically possible in 11 patients; the results are not included in this report.

There was poor agreement between a TUS finding of deep vein occlusion and the results of AP, and no agreement between TUS and ASGP (Table 1Go).


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  		Table 1. Patency of deep veins as assessed by triplex ultrasound compared with results of ascending phlebography and strain gauge plethysmography (with below knee compression cuff) in 38 patients with venous insufficiency

 
AP found reflux defined as missing or abnormal valves in only a few of the deep vein segments that were found incompetent at TUS (Table 2Go). CWD showed a very poor agreement with TUS. ASGP uniformly suggested incompetence irrespective of the site of reflux. The calculated values of Cohen's kappa for the agreement between results on reflux in the deep veins obtained with TUS and those obtained with AP, CW or ASGP were all less than 0.20, corresponding to poor agreement that could occur by chance. The estimated sensitivity of each method, referring to evaluation of common and superficial femoral veins, was 86%, 70% and 4% for AP, CWD and ASGP, respectively, and specificity was 0%, 38% and 100%, respectively. For the popliteal vein, sensitivities were 83%, 48% and 5%, and specificities were 17%, 75% and 100%, respectively, for each method.


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  		Table 2. Competence of deep, superficial and perforator veins as assessed by triplex ultrasound compared with results of ascending phlebography, continuous wave Doppler and strain gauge plethysmography (with below knee compression cuff) in 38 patients with venous insufficiency

 
Competence of the sapheno-femoral junction was found at TUS in 11 patients and incompetence in 20 patients. The values of kappa for the agreement between results obtained with TUS and those obtained with CWD, ASGP or, in the case of leg perforator veins, AP, were close to zero. The estimated sensitivity of the CWD was 70% when used for evaluation of the sapheno-femoral junction and 52% when used for evaluation of the sapheno-popliteal junction, and the corresponding values of specificity were 35% and 60%.

Sensitivities of ASGP were 0% and 5% for sapheno-femoral and sapheno-popliteal junction, respectively, and specificities were 94% and 100%, respectively. Referring to leg perforator veins, specificities were 76%, 91% and 97% for AP, CW, and ASGP, respectively. With CWD, 13 patients without insuffiency in the sapheno-femoral junction had insufficiency in the long saphenous vein or varicose segments. The corresponding figure for the short saphenous vein is 5 patients. For each patient, varying numbers of perforator veins with reflux were observed with the different methods used. Medially, one to three veins were observed at CWD, one to five veins at TUS and one to four veins at AP. Laterally, up to three veins were observed at TUS and up to two veins at AP.


   Discussion
Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
References
 
Venous ulceration is a common problem in European and Western populations, causing severe disability, and its prevalence has been estimated at approximately 1% [17]. The patients in this study all had clinically well established chronic venous disease and 36% had previously had clinical DVT. Therefore the aim of paraclinical examinations was not to confirm venous disease, which was achieved in all patients on TUS on and all but one patient on ASGP. The challenge was to compare five diagnostic methods for the demonstration of obstruction or insufficiency of the deep veins, which is of importance if operation on the superficial and perforator veins is considered [2–5], and for the demonstration of any site(s) of venous insufficiency in the deep, superficial and perforator veins.

TUS was chosen as the gold standard in this investigation [18–24]. When TUS on the basis of venous Doppler signals states that a particular vein is patent, it is difficult to imagine that this should not be true. Still, AP found occlusion in 10–15% of the femoral and popliteal veins that were diagnosed as patent at TUS. If there is an occlusion at phlebography of, for instance, the popliteal vein and no filling of the more proximal veins, one cannot tell whether this is owing to a real occlusion or lack of contrast [25]. On AP, the popliteal vein was described as occluded with collaterals in three patients, while TUS found it patent but with possible sequelae to DVT other than occlusion. An explanation for this discrepancy could be that, with AP, contrast material would more easily pass via the lower-resistance collaterals than through the narrow and stiff popliteal vein, and thereby suggest that the popliteal vein is occluded. AP shows only the vessel interior, while TUS also describes the exterior and surroundings.

ASGP vastly overdiagnosed deep vein occlusion. It should be emphasized that the plethysmographic method gives a functional evaluation of the entire venous system. During occlusion of the superficial veins, signs of reflux will be recorded regardless of the localization of the incompetent deep or perforator veins. Another explanation may be that the tourniquet used did not completely occlude the superficial veins, as the pressure required to prevent reflux within an incompetent long saphenous vein has been found to vary from 40 mm Hg to 300 mm Hg [26].

In the evaluation of deep vein patency we believe that TUS should be the examination of choice, and be supplemented by AP in dubious cases. ASGP gives no additional information in this situation.

Disagreements were observed concerning the insufficiency between TUS and the phlebographic examinations. According to the criteria of Thomas, an AP showing missing or abnormal valves should be synonymous with venous insufficiency [7], but it must be remembered that there is great variability in the number of venous valves among individuals, and valves decrease in number in the more proximal veins.

Disagreements concerning reflux were also observed between TUS and CWD, which was unreliable regarding evaluation of deep veins. CWD, however, diagnosed insufficiency in seven long saphenous veins/varicose veins and in five short saphenous veins not examined for at TUS because of competence of the sapheno-femoral and sapheno-popliteal junctions. Detection of any type of insufficiency of superficial veins is of importance since incompetence of the superficial system of the limb alone, or in combination with reflux in the perforating veins, account for 30–50% of limbs presenting with ulcers [27]. In patients with deep venous insufficiency, improvement in venous reflux and hypertension may be achieved by correction of superficial venous insufficiency, while the addition of ligation of perforating veins seems to be of less benefit to the venous circulation [28].

ASGP cannot differentiate between insufficiency of deep or perforator veins, and is therefore of little value in the work-up of deep venous insufficiency. This method does not allow precise localization of the diseased vein, and the value of the method using RT lies in the ability to demonstrate venous incompetence and in the assessment of the effect of treatment. Observations at ASGP of normal values for EV in 10 patients and normal RT in 1 patient are in contrast to the findings at TUS of abnormalities in one or more vein segments in all patients of the study. The concept of two hydrostatic columns, one deep and one superficial, is too simplistic to describe the situation in combined incompetence. Because communicating veins occur at all levels and allow overflow from insufficient superficial veins to the deep system, the below knee tourniquet fails in interrupting the high hydrostatic column [29].

Venous collaterals are easily demonstrated at both AP and TUS. At the ultrasound examination we have not, in this series, concentrated on differentiating between collaterals belonging to the deep or superficial venous system. It is possible to do this by adding longitudinal scanning to visualize whether the collaterals empty into the deep or superficial veins. At phlebography a lateral view is needed.

We conclude that AP should only be used in those few patients in whom TUS is inconclusive concerning the deep veins, and that CWD, because of lack of anatomic detail, should not be used. ASGP should be applied when functional evaluation of the entire venous system is needed.

We further conclude that optimal TUS examination in patients with leg ulcers should include an anatomic/morphological evaluation and an evaluation of the degree of venous insufficiency, including: (1) visualization of the deep veins, from the iliac veins to the ankle, for possible sequelae after venous thrombosis in the deep and superficial veins, and visualization of possible collateral veins and whether they are emptying into the deep or superficial vein system; (2) evaluation of venous valvular competence at all levels of the limb; and (3) evaluation of perforating veins of the thigh and calf.


   Footnotes
 
Financial support was provided by Coloplast A/S. Back

Received for publication January 2, 2001. Accepted for publication April 15, 2002.


   References
Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 

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