PMC7317322_01
The initial plain radiograph of the femur ((a) anteroposterior and (b) lateral) depicting (dotted line) a centrally located lytic lesion at the femoral diaphysis with concomitant reactive cortical thickness. The initial MRI scan of the lesion. (c) Short T1 reverse- (STIR-) weighted image (WI) coronal view. (d) T2WI axial view (see text for more details).
CRIONM2020-4052034.001.jpg
PMC7317322_01_CRIONM2020-4052034.001.jpg
fig1
Plain radiographs (Figures 1(a) and 1(b)) revealed the existence of a rounded and well-defined lytic lesion at the right femoral diaphysis with evidence of surrounding mild laminated chronic-type periosteal reaction.
Axial CT image (a) at three months post-RFA, revealing the existence of dystrophic calcifications (black arrow). Coronal MRI scan images of the diaphysis of the right femur of the patient at three months post-RFA, depicting a well-defined lytic lesion with central necrosis. The necrosis had an intermediate to low MR sign on T1WI ((b), white arrow) and prominent surrounding oedema on STIR ((c), arrowhead). After the intravenous administration of contrast media, the lesion showed enhancement only at its periphery ((d) short arrow).
CRIONM2020-4052034.002.jpg
PMC7317322_01_CRIONM2020-4052034.002.jpg
fig2
The CT scan revealed a central zone with fluid density due to necrosis (Figure 2(a)). The MRI scan confirmed the central necrosis of the tumor, a moderate enhancement at the periphery of the lesion and a mild surrounding bone oedema, which was a consequence of the RFA procedure (Figures 2(b)-2(d)).
Axial CT scan (a) at six months post-RFA, depicting the formation of callous at the cortex hole area (white arrow). MRI scan at six months post-RFA. (b) Coronal STIR images showing decreased surrounding oedema (when compared with the previous scan) and necrotic appearance of almost the entire lesion (black and white arrow). Axial T1WI images before (c) and after (d) the administration of contrast media, depicting the central necrosis (grey arrow) and the peripheral type of enhancement (short arrow).
CRIONM2020-4052034.003.jpg
PMC7317322_01_CRIONM2020-4052034.003.jpg
fig3
The CT scan depicted the existence of callus at the cortex hole area (Figure 3(a)). The MRI scan revealed a more prominent central necrosis, while the post-contrast enhancement and the surrounding bone oedema were decreased (Figures 3(b)-3(d)).
MRI scan at 48 months post-RFA. Axial (a) and coronal (b) T1WI images show no bone oedema (white arrow) and only minor cortical thickening (arrowhead). Proton density WI (PDWI) with fat suppression MRI scan image (c) verified the absence of bone oedema (grey arrow). Axial T1WI MRI scan image (d) following the administration of contrast media suppression show no enhancement.
CRIONM2020-4052034.004.jpg
PMC7317322_01_CRIONM2020-4052034.004.jpg
fig4
During subsequent follow-up visits at 12, 18, 24, and 36 months post-RFA, the MRI characteristics depicting necrosis at the RFA area gradually subsided, until they became normal at the last follow-up visit at month 48 (Figure 4).