CT MONITORING OF TREATMENT OF ENDOMETRIAL CARCINOMA
Huang Disheng, Ju Jiayin,
Zhang Hong, Shen Lan,
Sun Kun, He Guoqing
- Department of MRI/CT , Central Hospital, Mianyang, Sichuan
- Department of Ultrasound, General Hospital, China Army Police.
HIFU is a new technique for treating tumours without surgery that was developed independently in P.R. China in recent years. The heating effect of HIFU ablates the target tissues. CT is the main method for evaluating pathology after HIFU treatment.
Materials and Methods
- Patients were selected from a gynecology clinic, screened by imaging method from Dec. 2005 to Apr. 2007. There were 21 cases diagnosed with uterine cancer and opted for HIFU therapy for their uterine tumour. Age ranged from 20 to 55 years old, the mean age was 42.
- From 21 cases of uterine cancer, there were 22 tumours check out by CT. Twenty cases with 1 tumour, and one case with 2 tumours. The diameters of tumours ranged from 2.0 to 8.0cm. There were 13 tumours sized from 2.0 to 5.0cm, 9 tumours from 5.0 to 8.0cm. 13 tumours were endometrial; the other 9 tumours were sub-endometrial.
- Method: HIFU Tumour Therapy System, CZ901 manufactured by Mianyang Sonic Electronic Ltd., Sichuan Output Power 250W -300W. One point treatment between 5 to 10 seconds, actual time 50%, Focus of the treatment head: 170mm
- These 21 cases were scanned by CT in planned and enhanced multi-layer spiral ways, thickness of layer 2 to 3mm. Coordinate, MPR: vector, coronary. First scan was done during the week before the therapy. Callback after the therapy at 1, 3, 6, 12 months.
Follow up (monitoring) for the Therapy Results
CT, MRI (State Regulation 2003)
PET, Bone Tumour: ECT, DSA
Ultrasonic Image
Ultrasound was not the only follow up method
Pathologic Change after HIFU Therapy
HIFU therapy produced the instant high temperature and changed the physical functions in the target region, where the tissue protein was altered and repaired by ablation. Heat temperature ablation correlates to temperature and time: 43 Cby 12 hours., 70 Cby 0.25 seconds, 100 Cby 0.1 seconds. The treatment on the target burning spot ranged from just 0.5 to 1.0 seconds, temperature increased to 65 C - 100 C
Pathologic Change of the Ablated Repaired Region
Ablated repaired region being gradually absorbed, reduced and fibrosed (pedicel, calcify). The boundary between normal part and repaired part is clear (5 -7 layers of cells)
CT Display of Uterine Tumour
There is a difference between shuttle tumour cell and pedicel tissue, which could be calcified and degraded. CT can display lower, equal, and higher densities, as well as size and amounts. Enhancement could consolidate a bit, but it is usually lower than the normal tissue around it.
CT Display after HIFU Therapy
The ablation-repaired region is formatted rapidly, which can be checked out by CT one day after therapy. The boundary of the target's burning spot is clear. In the low density region, CT value is 20 to 30HU.
Immediately after treatment, the low density region of the burning spot is round and mixed with multi-spot slices, but the repaired region is not yet consolidated.
HIFU therapy in 21 cases, 22 tumours
CT checking, 4 weeks post therapy: 13 target tumours clearly appeared in low density, with no consolidation and the boundaries clear; all of which belong to ablated repaired tissue after HIFU therapy and can be measured exactly.
But in 6 of them, there were light consolidations in the thin circles around the target regions. Every case is measured by the product of maximum diameter by its perpendicular diameter.
In 5 target regions, there were low density areas with multi-spot slices which could not synchronize with each other. The areas could not be measured exactly since there were some shadows of isodensity slice mixed with them. In one case checked by CT 14 weeks post-therapy, the original ablated repaired region in low density was clearly reduced. Five cases (6 target regions) were checked by CT 34 weeks post-therapy, the original ablated repaired region in low density was clearly reduced, and one tumour was cleaned away completely.
CT Observation after Therapy
The recovery of the ablated repaired region usually starts from the boundary, it can be found by CT that the boundary of target region in low density is gradually faint, and the area smaller. This process is slow. Normally it will take 7 to 18 months for the repaired region to disappear, which correlates with the size of the target region. Consolidation gradually increased, it started from the circle boundary (pedicel) and filled in the repaired region. One of the cases showed calcinosis in a small slice.
Estimation Standard
According to the standard estimation for tumour therapy issued by WHO, it is measured by the product of the maximum diameter and its perpendicular diameter from the CT scan image of tumour. The therapy estimation is based on the measurement and observation of CT images in different times, before and after HIFU therapy.
Complete Recovery (CR): The ablated repaired region covers the full target region by CT observation. Partial Recovery (PR): The measurement is by two diameters. For single tumour target region, the rate of repaired region to tumour region is over 50%, the repair is measured by the product of maximum diameter and its perpendicular diameter. For the multi tumour target regions, the rate is the sum of all repaired regions to the sum of all tumour regions, and over 50%. Repaired regions calculated are the same as single one above. No Change (NC), Mild Recovery (MR) and Stabilized Deterioration (SD). MR: Ablated repaired region covers the tumour region between 25% to 50%. SD: Repaired region covers tumour region less than 25%, or tumour region increased not more than 25%. Pathologic Deterioration (PD). PD: The tumour increases over 25%, or new tumour produced.
The Results by CT Observation
After HIFU therapy, the results from CT observation for 21 cases of uterine tumour (22 tumours) are listed here, according to WHO Standard Estimation.
CR: 6 cases, 7 tumours
PR: 9 cases, 9 tumours
NC: 6 cases, 6 tumours
PD: 0 cases
The total efficiency (CR+PR) is 72.7%.
Conclusion
CT plays an important role in assessing the results of uterine tumour HIFU therapy. The therapy result is measured by the volume of, and the density change in, the ablated region. For uterine tumours, the recovery process of the repaired region is slow. For short term observation, emphasis should not be on the change of tumour volume. CT cannot detect the temperature in the tumour region, and should not be used during the HIFU procedure.