PMC5406223_01
Case of a patient previously treated for colorectal cancer presenting with PET-positive metastasis that was treated with percutaneous microwave ablation guided by fusion imaging and virtual navigation. (a). PET/CT images demonstrating a 4 cm FDG avid recurrence (arrow) located at the liver dome. (b). The lesion was completely invisible at ultrasound (arrow). (c). The lesion was undetectable at non-enhanced CT too (arrow). (d). Even contrast-enhanced ultrasound was not able to show the lesion due to the presence of interposed aerated lung parenchyma (arrow). (e). The treatment was performed using a system for image fusion that shows the real-time ultrasound in the upper left quadrant (arrow gas forming during ablation), the CT images on the upper right quadrant, the PET images in the lower right quadrant and the fused images in the lower left quadrant. (f). PET/CT after treatment showing complete ablation of the treated lesion.
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figure1
A 58-year-old male with history of resection of colorectal cancer two years earlier and percutaneous image-guided thermal ablation of a hepatic metastasis at segment VIII 10 months earlier was referred to our institution for possible local treatment of a 4 cm recurrence on the cranial side of the previously ablated area, which was detected by 18-FDG-PET/CT (Figure 1a). Given that in our centre, most liver thermal ablations are performed under ultrasound (US) guidance, we preliminarily performed an US examination to localise the lesion, but unfortunately, it was completely invisible on B-mode US (Figure 1b) due to its location in the liver dome, completely hidden behind the aerated lung. It was undetectable also on the unenhanced computed tomography (CT) of the positron emission tomography-CT (PET-CT) study (Figure 1c). Thus, we attempted to enhance the visibility of the lesion with CEUS, but due to the presence of the aerated lung, it was impossible to detect the lesion (Figure 1d). During ablation, the gas produced by heating was used to monitor the correctness of targeting (Figure 1e). At 24 hours from the treatment, we performed a PET/CT examinations, which demonstrated the complete ablation of the metastasis (Figure 1f).
PMC5406223_02
Case of an adrenal metastasis from lung cancer treated with percutaneous microwave ablation. (a,b). Preoperative CT demonstrated a 31 mm right adrenal metastasis (arrow) that was located in close proximity with critical structures such as pancreas (arrowheads in a) or stomach (arrowheads in b). (c). A small caliber needle was placed medially to the adrenal gland and CO2 injected in order to displace the lesion from surrounding critical structures. (d). A microwave antenna was inserted into the adrenal metastasis (arrow) and ablation was performed. (e). Final result 24 hours after ablation showing complete devascularisation of the lesion (arrow).
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figure2
When the patient was evaluated for ablation, the adrenal lesion measured 31 mm (Figure 2a). As the adrenal lesion was very close to sensitive surrounding structures, such as the stomach, the colon and the pancreas (Figure 2a, 2b), percutaneous injection of carbon dioxide (CO2) was planned in order to displace the sensible structure from the adrenal gland. A 21 G needle was percutaneously placed under CT guidance medially and deeper to the lesion, in its close proximity (Figure 2c). After the injection of CO2, we were able to achieve a good distribution of the gas around the gland and a good displacement of the surrounding structures (Figure 2c). At this point, the microwave antenna was inserted into the gland and the ablation was performed by using an energy of 60W for 6 min (Figure 2d). The control performed with contrast enhanced CT 24 hours after the treatment demonstrated the complete devascularisation of the treated lesion (Figure 2e), which was considered to be completely ablated.
PMC5406223_03
Laser ablation of a small HCC with US and CEUS guidance. (a). Oblique subcostal US (left side of the split screen) and contrast-enhanced US (right side of the split screen) scan of the right lobe of the liver, showing a 12 x 11 mm in size hyper-enhancing HCC in segment VI, strictly close to the liver capsule. (b). Oblique subcostal contrast-enhanced US scan of the right lobe of the liver, showing a residual hyper-enhancing focus 5 mm in size in the posterior portion of the nodule treated with LTA (arrow, right side of the split screen). (c). CEUS-guided insertion of the needle (arrow, right side of the split screen) towards the hyper-enhancing target (arrowhead, left side of the split screen); (d). A hyperechoic cloud is produced after delivery of 1800 J in 6 minutes. (e). Oblique intercostal contrast-enhanced US scan performed 5 minutes after retreatment showing a coagulation area of 20 x 16 mm with no evidence of viable tumour.
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figure3
One HCC was located in segment VII and measured 36 x 28 mm, the other one was located in segment VI strictly close to the liver capsule and measured 12 x 11 mm (Figure 3a). Contrast-enhanced US (CEUS) performed about 5 min after the end of the procedures depicted a coagulation area of 44 x 32 mm in segment VII with no evidence of residual hyper-enhancing foci, suggesting complete necrosis of the nodule treated with MWA. Conversely, a viable, hyper-enhancing focus of 5 mm in diameter was observed in the posterior portion of the nodule in segment VI treated with LTA (Figure 3b). The treatment was immediately repeated, and two laser fibres spaced 6 mm next to each other were placed into the residual tumour under CEUS guidance (Figure 3c). A further 1800 Joules per fibre was delivered in 6 min (Figure 3d), and CEUS performed 5 min after the retreatment showed a coagulation area of 20 x 16 mm with no evidence of viable tumour (Figure 3e).
PMC5406223_04
PET/CT-guided cryoablation of perisplenic metastasis in a patient with uterine cancer. (a). Contrast-enhanced CT shows the hypodense mass along the posterolateral border of the spleen (arrow) confirming a solitary peritoneal metastases. (b). Fused PET/CT image acquired using 35 s suspended ventilation prior to probe placement shows the FDG-avid perisplenic peritoneal mass positioned posterior and lateral to the spleen (arrow). The metastatic mass appears partially necrotic in the medial part of the tumour and indents the spleen (arrowheads). Note the radio-opaque skin markers overlying the spleen which are placed in order to help plan the exact coordinates for the placement of the cryoablation probes. (c). Another slice level of the fused planning PET/CT showing large FDG-avid perisplenic peritoneal metastasis (arrow) with its medial surface in close proximity to the left kidney and the anterior surface adjacent to the spenic flexure of the colon (arrowhead). (d). CT fluoroscopy images show placement of the needles and probes into the tumour. (e). CT fluoroscopy shows placement of a 20-G Chiba needle for hydrodisplacement of the splenic flexure of colon with instillation of dilute iodinated contrast into the space between tumour and colonic wall. This manoeuver prevents cryoablation injury of the bowel. (f). Fused PET/CT image shows placement of the hydrodisplacement needle between tumour and bowel wall (arrow). (g). Fused PET/CT at the level of the upper cryoablation probe performed after initial cryoablation shows a hypointense region encompassing the tumour (white arrowheads) which represents the cryoablation iceball. The area of FDG uptake (red arrow) remains unchanged as compared to initial planning PET/CT since FDG does not dissipate from the tumour during or following cryoablation. (h). Fused PET/CT performed towards the end of the cryoablation at the level of lower cryoablation probes shows persistent FDG uptake within the tumour and a hypodense iceball on CT extending beyond the FDG avid tumour. This confirms an adequate ablation margin including and extending beyond the entire tumour. Note the bowel wall is at a significant distant from the cryoablation zone which has been achieved by hydrodisplacement. (i) 3D VIBE breath hold contrast-enhanced MRI shows the hypoenhancing ablation zone (red arrow). No enhancing residual tumour visualised. (j). Follow-up contrast-enhanced CT (axial and coronal) shows the hypoenhancing ablation zone without enhancing residual tumour. There is a small area of reactive left pleural effusion (white arrow) which is expected following ablations adjacent to the diaphragm. The left renal margin adjacent to the ablation zone in the coronal image does not show significant cryoablation-related hypodensity, thus ensuring lack of significant renal parenchymal damage.
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figure4
CT, along the posterolateral border of the spleen suggestive of metastatic peritoneal disease (Figure 4a). Pelvic metastases were not visualised. Chemotherapy with doxorubicin was initiated, but the patient could not tolerate more than two doses. The resulting fused PET/CT images are also perfectly coregistered (Figure 4b and c). CT fluoroscopic guidance to reach the space between the anterior margin of the tumour and the bowel wall and a small volume of saline mixed with CT contrast was infused (Figures 4d, e and e). CT fluoroscopy was used to check the position of the instilled saline. PET/CT confirmation of proper placement of both cryoablation probes and hydro displacement needle, the cryoablation was started (Figure 4f). PET/CT performed during the cryoablation shows growth of the hypodense iceball encompassing the entire tumour (Figure 4g and h). She underwent a follow-up MRI the next day to assess the results of the cryoablation and to provide a baseline for future follow-up (Figure 4i).