الفهرس 
THE LIVEROnly 14 pages are availabe for public view
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Abstract
Microwave ablation is the most recent development in the field of Image Guided Thermal Tumor Ablation
The electromagnetic microwaves agitate water molecules in the surrounding tissue, producing friction and heat, thus inducing cellular death via coagulation necrosis.
The new simultaneous activation MWA system is adapted for the simultaneous activation of multiple-antenna clusters to achieve efficient production of large and controlled coagulation volumes to be used in large focal lesions.
Careful patient selection, choice of the most appropriate imaging modality, full pre-ablation imaging work-up is performed to accurately stage and locate the HCC lesions and to exclude tumor emboli and metastases. Proper coagulation status is needed to withstand the ablation procedures. MWA technique allows for flexible approaches to treatment, but percutaneous treatment is much preferable, as it is the least invasive, can be performed on an outpatient basis, and can be repeated in recurrent tumors. With imaging guidance (i.e., ultrasonography, computed tomography, magnetic resonance and fluoroscopy), the tumor is localized, and a microwave antenna is placed directly into the tumor and electromagnetic wave is emitted from generator to antenna. The therapeutic response is considered complete when contrasted CT or MRI showed no enhancement in the lesion.
Child-Pugh classification, tumor size, and number of tumors are identified as significant independent prognostic factors in patients with HCC treated with Microwave ablation.
The 5yrs survival rate with microwave ablation of HCC is fairly high. There is a significantly higher long term survival for patients with a single tumor of 4.0cm or smaller in maximum diameter and Child-Pugh class A cirrhosis.
Comparing to RF; MWA results in larger zone of active heating allowing for a more uniform tumor kill in the targeted zone and next to blood vessels. The electromagnetic nature of microwaves makes it not subject to tissue boiling and charring which act as electrical insulators, thus allowing the intra-tumoral temperature to be driven considerably higher, resulting in a larger ablation zone within a shorter ablation time.
MWA may be superior to PEI for the local control of moderately or poorly differentiated small HCC (<or= 15mm).
Microwave ablation may become one of the treatments of choice in Child-Pugh class C patients with small HCC lesions.
If local tumor recurrence is often due to survival of tumor cells near local blood vessels, MWA may help reduce recurrence following ablative therapy.
In the current study microwave ablation was utilized to treat 38 hepatic tumor nodules in 30 patients and treated with ultrasound-guided percutaneous MWA. The study group included 25 male patients (83.3%) and 5 female patients (16.6%), with age ranging from 50 to 70yrs (mean age 60.4yrs). The mean age of study cases was 64.45.8yrs; males represented 83.3% of cases. HBV and HCV were present among 33.3% and 93.3% of cases respectively. Diagnosis was made by typical computed tomography (CT) criteria of HCC by triphasic spiral CT with or without elevation of α-fetoprotein. Twenty five patients (83.3%) of the 30 patients had an increased serum α-fetoprotein level (>200g/L) and 5 patient had normal serum α-fetoprotein level (16.6%). All cases had CT enhancement before ablation (100%), with 83.3% had elevated AFP level.
All patients completed the procedure safely and the median ablation time was 10min (range: 5-15min). Technical success, as determined at dynamic CT performed 1 month after percutaneous MWA, was achieved in 38 (100%) of 38 nodules. All cases had No CT enhancement after ablation (100%), with 83.3%had decreases AFP level. Follow-up for all cases extended for 6 months with a mean of 4 months (162 days 81); including the first follow-up step at 1sth month after MWA then after 3-5 months; accordingly 10 (33.3%) patients were followed once, and 20 (66.6%) patients were followed twice. During this limited period, none of the patients died, no local recurrence was detected. However, new lesions at other sites of the liver occurred in 3 (10%) patients. The mean INR of study cases was 1.080.17; the mean ablation time was 9.435.5.
In the current study, no complication occurred related to the ablation procedure. After percutaneous MWA, one patients had mild pleural effusion. The effusion was relieved with the oral administration of analgesics and antibiotics and chest physiotherapy. One patient had small 2x2cm. subcapsular hematoma that resolved on follow up after two weeks with n o treatment. Five (16.6%) patients had a mild fever, which lasted 1-3 days. No other clinically relevant complications were observed. About 17% of cases had fever, 3.3% had hematoma and 3.3% had pleural effusion.