Methods for Objectification of the Results

(1)

Division of Plastic-, Hand-, and Microsurgery Department of Surgery, Ludwig Maximilians University, Munich, Germany

4.1 Volume Measurement

Changes after any kind of edema treatment in extremities should be measured as exactly as possible. Measurements of circumferences at single points reflect the differences insufficiently.

Measurement of volumes is more accurate.

We used the method according to Kuhnke (1976) which is widespread in Germany. The volume is calculated from measuring the circumferences at a distance of 4 cm. The measuring can be simply performed just with the help of a tape measure.

Kuhnke described different ways of calculating (Kuhnke 1976, 1978).

The disk model is the most appropriate one. The volume of the disk with a height of 4 cm is calculated having measured the circumference.

Circumference and volume are connected according to the equation:

${U}^2=\frac{4\pi }{h}\times V$

Since the height is 4, the equation is simplified:

$\frac{U^2}{\pi }=V$

The volumes of the disks are then added up and result in the volume of the extremity within the measured area (Fig. 4.1).

Fig. 4.1

Calculating the volume of an extremity by the disk model according to Kuhnke, adding the volumes of the disks with a height of 4 cm, measuring the circumference at the middle of single disks

Different methods for calculating the volume have been described. They are comparable if used in the same way during the investigation.

The optoelectronic method calculates continuously the volume by measuring the diameter of the extremity in two directions, moving a frame over the extremity.

During the procedure of the water replacement method, the extremity is immersed into a tube filled with water, and the water which is driven out is measured.

These methods are basis of investigations from other groups.

4.2 Nuclear Medical Investigation

Another important way to follow the results of treatment is to assess the function of the lymphatic system.

In order to repeat the measurements, a low-invasive procedure is necessary.

For quantification different ways have been proposed. Determining and measuring regions of interest require a strict protocol to give reproducible results.

Therefore the Department of Nuclear Medicine at the LMU performed lymphoscintigraphies without determining regions of interest. It is stated that this is a low-invasive, versatile, simple technique, which may be suited well to assess lymphatic function.

Verbal description of lymphoscintigraphic findings alone however fails to evaluate the different findings.

Therefore visually five criteria were assessed and scored:

The lymphatic transport kinetics, K:

0, no delay
3, low-grade delay
5, extreme delay
9, missing transport

The distribution pattern, D:

0, normal distribution, i.e., nearly no background
3, partial diffuse (e.g., only in the surroundings of a knee)
5, diffuse distribution
9, transport stop

The time to appearance of lymph nodes, T:

Time in minutes to the first appearance of regional lymph nodes
9, no appearance

The assessment of lymph nodes, N:

0, clearly demonstrated
3, faint visualization
5, hardly recognizable
9, no visualization

The assessment of lymphatic vessels, V:

0, clearly demonstrated
3, faint visualization
5, hardly recognizable
9, no visualization

“The transport index (TI) is then calculated by the formula

$\mathrm{T}\mathrm{I}=K+D+0.04T+N+V$

The rational for this formula is that all criteria are considered as equivalent.

Score values range from 0 to 9 including all integer numbers. Thus, TI values range between 0 (normal) and 45 (pathological) (Fig. 4.2, Table 4.1).

Fig. 4.2

Scheme of the lymphatic transport index

Table 4.1

Lymphatic transport index

Transport index
	Kinetics	Distribution	Time	Lymph nodes	Lymphatic vessels
	K	D	T	N	V
0	No delay	Normal	n = 0.04 × minutes	Clearly demonstrated	Clearly demonstrated
3	Low-grade delay	Partial diffuse		Faint visualization	Faint visualization
6	Extreme delay	Diffuse		Hardly recognizable	Hardly recognizable
9	Missing transport	Transport stop	No appearance	No visualization	No visualization

Transport index (TI 0–45; pathologic ≥ 10)

Normalization of T (min) is performed by the factor 0.04, i.e., 200 min (maximal delay of lymph node appearance) yields the score value 8. No appearance is evaluated by 9.”

An interobserver study in 179 investigations was performed. A second observer reassessed the 179 limbs without knowledge of the results of the first observer. The mean difference for TI was rather small (2.61). The correlation was 0.96.

Using TI = 10 to discriminate between normal and pathologic lymph drainage in 122 investigation, 38 were found true positive, 75 true negative, 8 false positive, and only 1 false negative. Thus, sensitivity was 97.4 % and specificity 90.3%.

Although evaluation of lymphatic transport kinetics depends on the experience of the investigator, a good reproducibility was demonstrated (r = 0.96).

Therefore, that quantification of scintigraphic findings has proved very useful especially in follow-up studies. This method was used therefore to control the effect of reconstructive lymph vascular surgery in different studies (Kleinhans et al. 1985; Weiss et al. 2002, 2003).

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