Purpose: This study investigates the efficacy of 3 Tesla magnetic resonance (MR) microimaging
for characterisation of primary melanoma. Technologies currently in use for non-invasive
characterization of melanoma (confocal microscopy, optical coherence tomography, or
high frequency ultrasound) are limited by restricted penetration depth. In contrast,
MR microimaging can determine the full depth of all tumors.
Methods: Five patients with primary melanomas of lateral dimension 1cm or greater were imaged
with a 3.7cm surface coil using a 3D gradient echo sequence (1). Nominal spatial resolution
was 0.18×0.12mm in-plane, with 1 to 2.0mm slice thickness. Tumour size was measured
as the lateral an intradermal extent of hyperintense change in the epidermis.
Results: High quality images were obtained from all five tumours. There was close correlation
between the tumor surface dimensions, Breslow thickness, and Clark levels estimated
by MR microimaging and histopathology. Measurment of tumor cross-sectional area in
successive MR microimaging slices enabled the estimation of tumor volume (Table).
|
|
|
|
MRI
|
Pathology
|
|
n°
|
sex/age
|
site
|
Volume(cm3)
|
Length(mm)
|
Width (mm)
|
Breslow(mm)
|
Clark
|
Length(mm)
|
Width(mm)
|
Breslow(mm)
|
Clark
|
|
1
|
F/57
|
shoulder
|
0.63
|
11
|
9
|
1.2
|
III
|
-
|
-
|
0.9
|
III
|
|
2
|
M/37
|
leg
|
0.72
|
10
|
9
|
1.5
|
III
|
11
|
8
|
1.6
|
III
|
|
3
|
M/76
|
nail thumb
|
0.23
|
11
|
8
|
5.6
|
IV
|
10
|
9
|
5.5
|
IV
|
|
4
|
M/36
|
scapula
|
0.12
|
8
|
7
|
4.6
|
IV
|
9
|
6
|
5.2
|
IV
|
|
5
|
F/47
|
knee
|
2.95
|
26
|
25
|
7.6
|
IV
|
25
|
25
|
7.5
|
IV
|
Conclusion: MR microimaging of primary melanoma demonstrates close correlation with the microscopic
features documented by histopathology. Breslow thickness is currently considered to
be the most reliable prognostic indicator. However, primary tumor volume as estimated
by MR microimaging may prove to be a more reliable indicator than tumor thickness
as tumor volume accounts for both lateral and vertical growth.
References: (1) King SB, Ryner LN, Tomanek B, Sharp JC, Smith IC. MR spectroscopy using multi-ring
surface coils. Magnetic Resonance in Medicine, 1999. 42: p. 655–664
