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method. Perometry can discriminate at 1mm for circumferences and to the nearest 10ml for volume. Perometry is probably the most accurate method of limb volume measurement (43) but it has some disadvantages. Drawbacks include difficulty in measuring the full length of the arm right up to the shoulders because of the necessary abduction of the limb for inserting the arm into the frame. In general the measurement, performed only to a height of 40 cm, provide no information about lymphedema located above the elbow (15). Another disadvantage is the size of the equipment, making it difficult to use in clinical context.
6. 3DLaserScanning(3D)(11,29,47)
The literature regarding this technique is very poor. Only 3 articles on laser scanning in lymphedema volume measurement has been found (11,29,47). 3D laser scanning is a technology that digitally captures the shape of physical objects using a line of harmless laser light. It works on the principle of triangulation. The laser probe is swept several time above the surface of the object – for example the arm of a patient. The probe projects a line of laser light onto the surface while a sensor camera continuously records the changing distance and shape of the laser line in three dimensions (XYZ) as it passes above the object. During this process, laser scanners generate “point clouds”. These data are registered and merged into one 3D representation of the limb and post-processed with various software in order to obtain anthropometric information (diameters - volumes - shape). Laser scanning has been studied in term of accuracy and reproducibility and compared with the gold standard, i.e. the water displacement method. Mc Kinnon et al. (29) affirmed that laser scanner has similar accuracy and superior a reproducibility compared to the water displacement method. As accuracy in water displacement decreases with the dimension of the object, the bigger the object volume is, the lower the accuracy is (29). According to it, the measures of a whole limb are less precise using water displacement method than laser scanning. Mc Kinnon et al. stated that a precise comparison could be made before and after treatment with laser scanning, because the scanning process produces a digitalized image of the arm. The results prove that laser scanning measure is extremely close to the real volume with very low coefficient of reproducibility – define by the British Standard Institution as twice standard deviation of the difference between two measurements.
DISCUSSION AND CONCLUSION
Aim of this study is a review on the most common techniques used to evaluate lymphedema volume. Firstly, we observed that in literature more attention is on the lymphedema problem as well as on treatments for its reduction, than on the techniques used to measure the lymphedema entity in terms of upper limb volume. Focusing the attention on methods to measure upper limb volume in presence of lymphedema, we found 51 works, which allowed identifying 5 main techniques. For all methods, after a presentation of measurement procedures and the applications on pathological state, their advantages and limitations have been discussed.
The five methods are water displacement, tape measurement, perometry, bioelectrical impedance and laser scanning technique. Water displacement represents the gold standards and is a reliable method of measuring limb volume, though its use is not very practical in a clinical setting because of water spillage and space considerations (1,23). Perometry is very accurate but the cost of the machine limits it to specialist centres (4). Circumferential method with tape is widely used, because of its limited cost, but the estimation of arm volume is subject to several potential errors mainly related to the interobserver variation (46). The laser scanning procedure is painless and simply requires passing a low energy laser over the skin of the limb. It is accurate, reliable, not time consuming and its cost is quite moderate (15,29). Another important aspect to take in considerations to evaluated the most suitable method for clinical application is the test duration. Literature underline that volumetric method is time consuming compared with tape measurements; the needed preparation and clean up add significantly to overall measurement time (9,15,26). Circumferential method took approximately 10 minutes to perform bilateral evaluation of the upper limbs (15), as opposed to the water volumetry method which takes approximately six minutes to set up and perform. Bioimpedance procedure takes less than 1 minute (37), while perometry is the quickest method, taking only a few seconds, provides segmental information. Laser scanning is also quite fast – approximately 5-10 minutes for scanning a whole arm and to calculate the entire volume (29). From our review, it is evident that both the wide variety of methods described in the literature and the lack of standardization make difficult for the clinician to assess the best volumetric method. According to clinical needs, the volumetric device should be easy to use, accessible, not expensive, reliable, accurate and quantifiable (1). From our analysis, the laser scanning seems to be the most proper technique for the volume evaluation of lymphedema among the other described techniques. In comparison with other methods, laser scanning presents good accuracy and reliability together with its facility of use, leading it suitable for clinical application. However, literature on this method is very scanty. In our opinion, further researches should extend the application of this method to assess the entity of the lymphedema as well as to evaluate the effects of treatments for its reduction. In addition, the same technique could be used for the measuring the entity of lymphedema, not only of the upper limb but also of other body segments, e.g. the lower limbs.
REFERENCES
1. NG M., Munnoch A. (2010): Clinimetrics of volume measurement in upperl limb LE. J. lymphoed., 5: 62-67.
2. Kissin M., Querci della Rovere G., Easton D. et al. (1986): Risk of lymphoedema following the treatment of breast cancer. Br. J. Surg., 73: 580-584.
3. Balzarini A., Lualdi P., Lucarini C. et al. (2006): Biomechanical evaluation of scapular girdle in patients with chronic arm lymphedema. Lymphology, 39: 132-140.
4. AA. VV. (2006): Lymphoedema Framework. Best Practice for the Management of Lymphoedema. International consensus, London, UK.
THE EUROPEAN JOURNAL OF LYMPHOLOGY - Vol. XXIX - Nr. 75 - 2017
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