The value of magnetic resonance imaging in assessment of carcinoma of the cervix and its response to radiotherapy

Determination of tumour regression rates during radiotherapy for cervical carcinoma by serial MRI: comparison of two measurement techniques and examination of intraobserver and interobserver variability

Tumour regression rates of 11 patients with cervical carcinoma were estimated during external beam radiotherapy (EBRT) using serial MRI (average time interval 7 days; range 3-15 days). An average of five investigations (range 4-8) was performed per subject. Tumour volume was measured by two observers using the Cavalieri method of modern design stereology in combination with (a) planimetry and (b) point counting. The mean precision of all the volume estimates obtained by manually tracing the outline of the tumour was 6.6%. The mean precision obtained by counting an average of 176 points per investigation on the same transects was 6.7%. The intraobserver repeatability of planimetry, interobserver reproducibility of planimetry and point counting were excellent with no significant difference between the volume estimates obtained using either technique. Based on the planimetry measurements, initial tumour volumes ranged from 6.5 to 222 cm3 (mean 63 cm3, median 44 cm3). Based on the point counting measurements, initial tumour volumes ranged from 7.2 to 235 cm3 (mean 68 cm3, median 46 cm3). Tumour regression began within a few days of commencing EBRT and showed an exponential relationship with time (p < 0.01). There was good agreement between the regression rates obtained by planimetry and those obtained by point counting. No significant correlation was found between initial tumour volume and tumour regression rate for either planimetry or point counting. Planimetry measurements were, on average, obtained in about half the time taken for point counting (i.e. 30 min and 50 min, respectively). Although point counting is generally likely to be the more efficient approach, planimetry may be the preferred approach for estimating tumour volume when a purpose built track ball is available and the tumour morphology is relatively simple. Volume measurement should be obtained using the Cavalieri method to ensure that the estimates are unbiased and that their precision can be predicted. The measured tumour regression rates may have important implications for improving local tumour control, optimum timing of brachytherapy and minimizing the risk of radiation damage.

Predictive value of clinical examination, transrectal ultrasound and magnetic resonance imaging prior to radiotherapy in carcinoma of the cervix

The objectives of this study were to compare tumour staging and volume assessment by examination under anaesthesia (EUA), transrectal ultrasound (TRU) and magnetic resonance imaging (MRI) in patients with invasive carcinoma of the cervix, and to correlate findings with long-term outcome following treatment by radiotherapy. Tumour staging was performed on 60 patients immediately before starting radiotherapy. Clinicians and radiologists performing EUA, TRU or MRI were blinded to the results of other investigations. Tumour stage and dimensions were recorded prospectively for each technique, and analysed for concordance. The relationship between pre-treatment stage, size of tumour and patient outcome after radiotherapy was assessed, using clinical status 5 years after treatment as the truth measure. EUA, TRU and MRI assigned the same tumour stage in only 30% of patients and EUA and MRI agreed tumour stage in a further 27%. In cases of disagreement, the MRI stage correlated better with outcome than the TRU or EUA stage. There was a significant difference between tumour volume obtained from measurements made on MRI and those from TRU. 62% of patients with enlarged lymph nodes on pre-treatment MRI either died, or developed tumour recurrence or metastases. The ability of MRI to assess the full extent of bulky tumours and the presence of lymph node enlargement was an advantage over both EUA and TRU in identifying patients with a poor prognosis.

Computerized axial tomographic scan measurements as prognostic indicators in patients with cervical carcinoma

This retrospective study of 56 patients with carcinoma of the uterine cervix treated with radical radiotherapy at the Royal Marsden Hospital, London, examined whether simple measurements of maximum tumour dimension from computerized axial tomographic (CT) scans have any prognostic significance. Our results indicate that tumour depth (i.e. maximum antero-posterior dimension) of 4 cm or more is associated with a statistically significant increased relative risk of death of 2.4 (95% CI 1.1-5.5; p = 0.045), as compared with tumours with a depth of less than 4 cm. In addition, there was a clear correlation between tumour depth and lymph node involvement (r = 0.36; p < 0.01), and tumour depth and width (r = 0.70; p < 0.005). We suggest that a measurement of maximum tumour depth from the staging CT scan in these patients provides valuable additional information about likely occult lymph node metastases and prognosis, over and above that suggested by the FIGO staging system alone.