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

Volume estimation of brain ventricles using Cavalieri's principle and Atlas-based methods in Alzheimer disease: Consistency between methods

Automatic estimations of brain ventricles are needed to assess disease progression in neurodegenerative disorders such as Alzheimer Disease (AD). The objectives of this study are to evaluate the diagnostic performances of an automated volumetric assessment tool in estimating lateral ventricle volumes in AD and to compare this with Cavalieri's principle, which is accepted as the gold standard method. This is across-sectional volumetric study including 25 Alzheimer patients and 25 healthy subjects undergoing magnetic resonance images (MRI) with a 3D turbo spin echo sequence at 1.5 Tesla. The Atlas-based method incorporated MRIStudio software to automatically measure he volumes of brain ventricles. To compare the corresponding measurements, we used manual point-counting and semi-automatic planimetry methods based on Cavalieri's principle. Bland-Altman test results indicated an excellent agreement between Cavalieri's principle and the Atlas-based method in all volumetric measurements (p < 0.05). We obtained a 64% sensitivity and 92% specificity for lateral ventricular volumes according to the Atlas-based method. AD subjects had significantly larger left and right lateral ventricle volume (LVV) when compared to control subjects in respect to three volumetric methods (p < 0.01). Lateral ventricle-to-brain ratio (VBR) statistically increased 49.23% in measurements done with the point-counting method, 45.12% with the planimetry method, and 45.49% with the Atlas-based method in AD patients (p < 0.01). As a result, the Atlas-based method may be used instead of manual volumetry to estimate brain volumes. Additionally, this method provides rapid and accurate estimations of brain ventricular volumes in-vivo examination of MRI.

Monitoring Tumor Volume in Patients With Prostate Cancer Undergoing Active Surveillance: Is MRI Apparent Diffusion Coefficient Indicative of Tumor Growth?

OBJECTIVE

The purpose of this study was to measure longitudinal change in tumor volume of the dominant intraprostatic lesion and determine whether baseline apparent diffusion coefficient (ADC) and change in ADC are indicative of tumor growth in patients with prostate cancer undergoing active surveillance.

SUBJECTS AND METHODS

The study group included 151 men (mean age, 68.1 ± 7.4 [SD] years; range, 50-83 years) undergoing active surveillance with 3D whole prostate, zonal, and tumor volumetric findings documented at endorectal MRI examinations performed at two time points (median interval, 1.9 years). Tumor (location confirmed at transrectal ultrasound or template biopsy) ADC was measured on the slice with the largest lesion. Twenty randomly selected patients had the measurements repeated by the same observer after a greater than 4-month interval, and the limits of agreement of measurements were calculated. Tumor volume increases greater than the upper limit of agreement were designated measurable growth, and their baseline ADCs and change in ADC were compared with those of tumors without measurable growth (independent-samples t test).

RESULTS

Fifty-two (34.4%) tumors increased measurably in volume. Baseline ADC and tumor volume were negatively correlated (r = -0.42, p = 0.001). Baseline ADC values did not differ between those with and those without measurable growth (p = 0.06), but change in ADC was significantly different (-6.8% ± 12.3% for those with measurable growth vs 0.23% ± 10.1% for those without, p = 0.0005). Percentage change in tumor volume and percentage change in ADC were negatively correlated (r = -0.31, p = 0.0001). A 5.8% reduction in ADC indicated a measurable increase in tumor volume with 54.9% sensitivity and 77.0% specificity (AUC, 0.67).

CONCLUSION

Tumor volume increased measurably in 34.4% of men after 2 years of active surveillance. Change in ADC may be used to identify tumors with measurable growth.

Effect of bladder distension on doses to organs at risk in Pulsed-Dose-Rate 3D image-guided adaptive brachytherapy for locally advanced cervical cancer

PURPOSE

To evaluate the impact of bladder distension on doses to organs at risk in patients treated with 3D image-guided adaptive pulsed-dose-rate (PDR) brachytherapy (BT) for locally advanced cervical cancer.

METHODS AND MATERIALS

Twenty-two patients who had previously been treated by external beam radiation therapy (EBRT), underwent BT treatment planning to a pelvic MRI (or a CT scan in case of contraindication) after their bladder was filled with 100 cc of physiological saline (full bladder). This was immediately followed by a CT scan after emptying of the bladder. A fusion of these two examinations was conducted, and the dosimetry was duplicated for the study with an empty bladder. Equieffective doses of 2 Gy per fraction from EBRT and BT of bladder/rectum/sigmoid colon/small bowel were compared.

RESULTS

A full bladder condition was found to be non-inferior in terms of the bladder D2cc (a difference of -0.9 Gy; 97.5% CI [-∞; 2.6]), and it resulted in a reduction in the bladder D0.1cc (p = 0.038). Bladder expansion resulted in a significant reduction of maximum doses received by the small bowel, both in terms of the D0.1cc (51.2 Gy vs. 63.4 Gy, p < 0.001) and the D2cc (48.5 Gy vs. 53.6 Gy, p < 0.001). A negative correlation was seen between the difference in the small bowel D2cc and the body mass index; (r = -0.55; p = 0.008). No differences were noted in regard to doses to the rectum and sigmoid colon.

CONCLUSIONS

Bladder distension with 100 cc of physiological saline can reduce maximum doses received by the small bowel without the alteration of the doses received by the other organs at risk during a 3D image-guided adaptive PDR BT for locally advanced cervical cancer. However, the maintenance of a predefined bladder volume is difficult to achieve with PDR BT, whereas it could be easily managed before each session in case of high-dose-rate BT.

Response patterns of recurrent glioblastomas treated with tumor-treating fields

Glioblastoma multiforme (GBM) is the most common form of primary malignant brain cancer. Median overall survival (OS) for newly diagnosed patients is only about 12 to 18 months. GBM tumors invariably recur, and there is no widely recognized and effective standard treatment for recurrent GBM. NovoTTF Therapy is a novel and US Food and Drug Administration (FDA)-approved antimitotic treatment for recurrent GBM with potential benefits compared with other options. Recurrent GBM patients from two prior trials with demonstrated radiologic tumor response to single-agent NovoTTF Therapy were analyzed to better characterize tumor response patterns and evaluate the associations between response, compliance, and OS. In addition, a compartmental tumor growth model was developed and evaluated for its ability to predict GBM response to tumor-treating fields (TTFields). The overall response rate across both trials was 15% (4% complete responses): 14% in the phase III trial (14/120) and 20% (2/10) in a pilot study. Tumor responses to NovoTTF Therapy developed slowly (median time to response, 5.2 months) but were durable (median duration, 12.9 months). Response duration was highly correlated with OS (r(2) = .92, P<.0001), and median OS for responders was 24.8 months. Seven of 16 responders exhibited initial tumor growth on magnetic resonance imaging. Compliance appeared to be linked with both improved response and survival. The tumor growth model predicted tumor arrest and shrinkage only after several weeks of continuous NovoTTF Therapy, consistent with the observed clinical findings of initial transient tumor growth in some patients. NovoTTF Therapy is a novel antimitotic treatment for recurrent GBM associated with slowly developing but durable tumor responses in approximately 15% of patients. Some responders exhibit initial tumor growth before shrinkage, indicating treatment should not be terminated prior to allowing for the full effect of NovoTTF Therapy to be realized. OS is longer in responders than in nonresponders. High daily compliance rates may be associated with increased likelihood of an objective response and are predictive of improved survival.

The effect of cyclooxygenase-2 expression on tumor volume response in patients treated with radiotherapy for uterine cervical cancer

We investigated the correlation between Cyclooxygenase-2 (COX-2) expression and the tumor response in patients with cervical cancer that were treated with curative radiotherapy (RT). Fifty-seven patients with squamous cell carcinoma were treated with concurrent radiochemotherapy (CRCT, n=29) or RT alone (n=28). The response of each patient was evaluated by three serial Magnetic Resonance Imaging examinations: before the start of RT, at four weeks after the start of RT (mid-RT) and at four weeks after the completion of RT (post-RT). Forty-three patients had positive COX-2 expression. The COX-2 negative patients achieved a higher rate of complete response (CR) at mid-RT than did the COX-2 positive patients (28.6% vs. 7.0%, P=0.054), but not at post-RT (64.3% vs. 69.8%). The initial tumor volume was a significant predictor of CR at mid-RT (P=0.003) and post-RT (P=0.004). The multivariate analysis showed that the initial tumor volume (at mid-RT and post-RT) and CRCT (at post-RT) were significant predictors of CR; however, the COX-2 expression was not. In conclusion, the COX-2 expression status has no significant correlation with the tumor response. Further studies on the changes in COX-2 expression levels during RT may be helpful for determination of its role in the tumor response to treatment and patient prognosis.

Endoscopic imaging and size estimation of colorectal adenomas in the multiple intestinal neoplasia mouse

BACKGROUND

The scientific potential of animal models of carcinogenesis has not been fully realized because of our limited ability to monitor tumor growth in vivo.

OBJECTIVE

To develop an endoscopy-based protocol for the accurate estimation of adenoma size in vivo from images obtained during colonoscopy.

DESIGN

To compare estimates of lesion size acquired during endoscopy with those obtained from magnetic resonance imaging (MRI) and at necropsy.

SETTING

A small-animal imaging facility.

SUBJECTS

Adenomatous polyposis coli multiple intestinal metaplasia Fox Chase Cancer Center mice that develop multiple colorectal adenomas.

METHODS

The mice received colonoscopic examination by using a rigid endoscope, and high-resolution images of colon adenomas were captured by using a charge-coupled-device camera. Lesion size was estimated by comparing the dimensions of the adenoma relative to a reference rod by using a novel geometric construction. The resulting areas were compared with estimates from MRIs and validated at necropsy.

MAIN OUTCOME MEASUREMENTS

Cross-sectional area of colon adenomas.

RESULTS

The cross-sectional area of 20 adenomas was measured in vivo during colonoscopy and compared with the size as measured at necropsy, which yielded a Pearson correlation coefficient of 0.94 (P = 6.52 x 10(-9)). Assessment of interoperator variability, when using measurements from 11 adenomas, yielded a Pearson correlation coefficient of 0.85 (P = 4.35 x 10(-3)) and demonstrated excellent reproducibility.

LIMITATIONS

Only the distal colon could be viewed, and endoscopic measurements were 2-dimensional.

CONCLUSIONS

An endoscopic method for the reliable measurement of colorectal adenomas in vivo was established. The application of this technique to mouse models of colon carcinogenesis will provide unique insight into the dynamics of adenoma growth.

Comparison of tumor regression rate of uterine cervical squamous cell carcinoma during external beam and intracavitary radiotherapy

PURPOSE

We compared the radioresponse of cervical carcinoma that was closely related to local disease control by the tumor regression rate (RR) during intracavitary radiotherapy (ICRT) and external beam radiotherapy (EBRT) on the presumption that ICRT has a stronger treatment impact than EBRT because of its specific dose distribution.

MATERIALS AND METHODS

A total of 37 patients were treated by EBRT at 45.0 Gy over 5 weeks, followed by high-dose-rate ICRT at 6.0 Gy per weekly insertion at point A three to five times and by boost EBRT. RR was defined as the slope (day(-1)) of the tumor-volume shrinkage curve fit to an exponential regression equation. Assuming that the tumors were ellipsoid, the tumor volume was estimated using magnetic resonance (MR) images obtained before treatment, after 45.0 Gy of EBRT, and after the third ICRT insertion. RRs were compared based on the radiotherapy method.

RESULTS

RR ranged between -0.008 to 0.093 day(-1) (median 0.021 day(-1)) during EBRT and -0.001 to 0.097 day(-1) (median 0.018 day(-1)) during ICRT, showing no significant difference or correlation between treatments.

CONCLUSION

Contrary to expectations, RR did not directly relate to the impact of physical treatment. RR could be related to biological factors, such as the amount of tumor clearance and changes in tumor consistency during treatment.

Comparison of four methods for the estimation of intracranial volume: a gold standard study

Investigators can infer how much reduction in volume has occurred since brain volume was at its peak, by combining measures of brain volume with measures of intracranial volume (ICV). Several methodologies have been proposed to asses the ICV. However, we have not seen a gold-standard study evaluating the results of the methodologies for the assessment of ICV. In the present study, the actual intracranial volume of 20 dry skulls was measured using the water-filling method, using this as a gold standard. Anthropometry, cephalometry, point-counting, and planimetry techniques were applied to the same skulls to estimate the ICV. Anthropometric and cephalometric measurements were carried out directly on skulls and roentgenograms, respectively. Consecutive computed tomography sections at a thickness of 10 mm were used to estimate the ICV of the skulls by means of the point-counting and planimetry methods. The mean (+/-SD) of the actual ICV measured by the water-filling method was 1,262.0 +/- 160.4 cm(3) (1,389.5 +/- 96.5 cm(3) for males and 1,134.5 +/- 94.3 cm(3) for females, respectively). Our results showed that the estimated values obtained by all four methods differed from the actual volumes of the skulls (P < 0.05). The data obtained by anthropometry resulted in overestimation. However, cephalometry, point-counting, and planimetry methods produced underestimation. After calibration, there were no significant differences between the actual volumes and the results of the four methods (P > 0.05). While the anthropometric method is easy and quick to apply, its result may deviate from the actual values. The optimized stereological techniques of point-counting and planimetry methods may provide unbiased ICV results since they take the third dimension of the structures into account.

Explanation for the failure of neoadjuvant chemotherapy to improve outcomes after radiotherapy for locally advanced uterine cervical cancer from the standpoint of the tumor regression rate

PURPOSE

Treatment outcomes for patients with locally advanced cervical cancer are no better with neoadjuvant chemotherapy (NAC) combined with radiotherapy (RT) than with RT alone. We investigated the reason for this failure from the standpoint of the tumor regression rate (RR).

MATERIALS AND METHODS

A total of 48 patients with clinical stage IIB-IVA cervical squamous cell carcinoma were treated clinically with cisplatin-based NAC plus RT (n = 15) or RT alone (n = 33). The RR was defined as the slope of a tumor shrinkage curve derived with magnetic resonance images. The local control rate (LCR) and disease-free rate (DFR) were estimated by clinical stage (IIB vs. III-IVA), pretreatment volume (< or = median vs. > median), lymph node status (negative vs. positive), treatment type, overall treatment time (< or =8 weeks vs. >8 weeks), and RR (< or = median vs. > median) using univariate and multivariate analyses.

RESULTS

RR during NAC or during NAC and RT (n = 15) was not significantly higher than RR by RT alone (n = 33). Low RR and positive nodal status were significantly powerful prognostic factors for both the LCR and DFR, whereas the others were not.

CONCLUSION

Although effective in reducing tumor volume prior to RT, NAC showed no overall effect in increasing the RR, which was shown to be the most powerful prognostic factor.

Comparison of Three Methods for the Estimation of Total Intracranial Volume

There is a well-known close relationship between the total intracranial volume (TIV) and the brain size. Several studies in different countries have estimated the cranial capacity, which indirectly reflects the brain volume. However, we have not seen a study evaluating the results of the methodologies for the assessment of TIV. This study was carried out on 30 normal subjects whose ages ranged between 19 and 77 years old (males, 18; females, 12). Three different methods were used to assess the TIV. The mean (+/-SD) estimated TIV using linear dimensions method in males and females were 1416.8 +/- 64 cm and 1291.9 +/- 152 cm, respectively. The mean estimated TIV using point counting method in males and females was 1474 +/- 93 cm and 1252 +/- 72 cm, respectively. By using the planimetric method of the mean and SD of TIV, male and females were 1492.1 +/- 74 cm and 1319.6 +/- 100 cm, respectively. There were no statistical difference between TIV measurements obtained using the optimized stereologic technique and planimetry (P > 0.05). TIV between males and females was statistically significant (P < 0.001). This study showed that there are minor differences among the given 3 distinct methods. With the disadvantage of requiring more time to apply, the planimetry and point counting methods provide more assumption-free results than the anthropometric approach. However, the anthropometric method can be applied to assess TIV without needing sophisticated tools.

Nouveautés en curiethérapie gynécologique : nouvelles technologies, curiethérapie pulsée, imagerie, définitions de nouveaux volumes d'intérêt et leur impact sur la dosimétrie : applications dans le cadre d'un STIC

Brachytherapy plays a fundamental role in the therapeutic approach of patients with stage I-IV cervical carcinoma. Technical modalities have evolved during the last decades: stepping source technology, imaging modalities development, specially IMN, treatment planning system integrating 3D images. Images from CT-Scan and MRI have contributed to a better knowledge of tumoral extension and critical organs. CT and/or MRI compatible applicators allow a sectional image based approach with a better definition of tumour volume compared to traditional approaches. The introduction of 3D image based approach for GTV and CTV requires new definitions and a common language. In 2000, a working group within GEC-ESTRO was created to support 3D image based 3D treatment planning approach in cervix cancer BT. The task was to determine a common terminology enabling various groups to use a common language. Recommendations were described and proposed based on clinical experience and dosimetric concepts of different institutions. Two CTVs were described en relation to the risk for recurrence: high-risk CTV and intermediate risk CTV. In order to better define the role of such definitions and their potential impact on the complication incidence in patients with cervical cancer, a special French programme was developed. The aim of this programme is to study the incidence of the severe 2-year complication rate in two comparable patient populations: one population is treated using PDR brachytherapy with CT-Scan or MRI with the applicators in place allowing a 3D dosimetry with optimization, the second population is treated using standard X-rays radiographs without any delineation of the target nor optimisation. Each population arm includes 425 patients. A medicoeconomic assessment is performed, allowing a real cost of the most sophisticated approach compared to a historical dosimetric system.

Early determination of uterine cervical squamous cell carcinoma radioresponse identifies high- and low-response tumors

PURPOSE

To investigate whether early-assessed radioresponse of tumors corresponds with late-assessed radioresponse, which is associated with local disease control in radiotherapy (RT) for cervical cancer.

METHODS AND MATERIALS

This prospective study included 12 patients with cervical squamous cell carcinoma treated by RT with or without concurrent cisplatin. Tumor volume was estimated by scheduled magnetic resonance imaging before (preRT), 3 to 4 weeks after (early assessment), and 6 to 7 weeks after (late assessment) RT initiation. Radioresponse was assessed with tumor shrinkage curves based on these volumes. Radioresponse for each tumor was calculated as the slope (day(-1)) of the shrinkage curve by fitting to an exponential equation.

RESULTS

Early-assessed radioresponse ranged from 0.001 to 0.106 day(-1) (median, 0.021 day(-1)) and late-assessed radioresponse from 0.009 to 0.091 day(-1) (median, 0.021 day(-1)), with no significant difference between them (p = 0.1191). The early-assessed radioresponse correlated with the late-assessed radioresponse (R(2) = 0.714, p = 0.0005).

CONCLUSIONS

Correspondence between early- and late-assessed radioresponse in a series of tumors showing a wide range of radioresponse was not particularly close overall. However, early assessment of radioresponsiveness did seem to be useful for characterizing those tumors with high or low radioresponsiveness.

CT-guided intracavitary radiotherapy for cervical cancer: Comparison of conventional point A plan with clinical target volume-based three-dimensional plan using dose–volume parameters

PURPOSE

To perform an intracavitary radiotherapy (ICR) plan comparison between the conventional point A plan (conventional plan) and computed tomography (CT)-guided clinical target volume-based plan (CTV plan) by analysis of the quantitative dose-volume parameters and irradiated volumes of organs at risk in patients with cervical cancer.

METHODS AND MATERIALS

Thirty plans for 192Ir high-dose-rate ICR after 30-40-Gy external beam radiotherapy were investigated. CT images were acquired at the first ICR session with artifact-free applicators in place. The gross tumor volume, clinical target volume (CTV), point A, and International Commission on Radiation Units and Measurements Report 38 rectal and bladder points were defined on reconstructed CT images. A fractional 100% dose was prescribed to point A in the conventional plan and to the outermost point to cover all CTVs in the CTV plan. The reference volume receiving 100% of the prescribed dose (V(ref)), and the dose-volume parameters of the coverage index, conformal index, and external volume index were calculated from the dose-volume histogram. The bladder, rectal point doses, and percentage of volumes receiving 50%, 80%, and 100% of the prescribed dose were also analyzed.

RESULTS

Conventional plans were performed, and patients were categorized on the basis of whether the 100% isodose line of point A prescription dose fully encompassed the CTV (Group 1, n = 20) or not (Group 2, n = 10). The mean gross tumor volume (11.6 cm3) and CTV (24.9 cm3) of Group 1 were smaller than the corresponding values (23.7 and 44.7 cm3, respectively) for Group 2 (p = 0.003). The mean V(ref) for all patients was 129.6 cm(3) for the conventional plan and 97.0 cm3 for the CTV plan (p = 0.003). The mean V(ref) in Group 1 decreased markedly with the CTV plan (p < 0.001). For the conventional and CTV plans in all patients, the mean coverage index, conformal index, and external volume index were 0.98 and 1.0, 0.23 and 0.34, and 3.86 and 2.15, respectively. Statistical analysis showed that the conformal index and external volume index improved significantly with the CTV plan, and this improvement was more marked in Group 1. The mean values of the bladder and rectal point doses and volume fractions receiving 50%, 80%, and 100% of the reference dose did not differ between plans for all patients. The reduction in the mean rectal and bladder point doses and irradiated volumes for the CTV plan was statistically significant in Group 1.

CONCLUSION

Computed tomography-guided CTV planning of ICR is superior to conventional point A planning in terms of conformity of target coverage and avoidance of overdosed normal tissue volume. To ascertain the potential benefit of treatment outcome, ICR with image-guided three-dimensional plans will be pursued and correlated with the dose-volume parameters.

Assessment of the optimum section thickness for the estimation of liver volume using magnetic resonance images: a stereological gold standard study

Estimation of liver volume using magnetic resonance (MR) images has been described previously. We have, however, not found a gold standard study, which analyzes the effect of section thickness on the estimation of liver volume. In the present study, five normal cadaveric livers were scanned in the horizontal plane using a 1.5 T MR machine (Signa 1.5T SYS#GEMSOW General Electronic, Wisconsin, USA). Consecutive sections at a thickness of 10, 7.5, 5 and 2.5 mm were used to estimate the total volume of the livers by means of the Cavalieri principle. The point counting and planimetry were used for the volume estimates. With a view to evaluating the accuracy of two techniques, all the estimations were done by the same observer. The estimated volumes concur with the actual volume of the livers obtained by the fluid displacement technique (p > 0.05). However, the section thickness has an over- or under-projection effect on the estimated volume. The obtained volume estimation results were analyzed to reveal the deviation principles of the estimates based on the section thickness. The most suitable section thickness for the liver volume estimation was assessed to be 4-5 mm. There were no significant differences between the estimation results of two methods (p > 0.05). The point-counting technique did, however, take less time than planimetry for estimating liver volume from MR images. Results also showed that the effect of section thickness on volume estimates using the two approaches could not be omitted and the values obtained could be calibrated using the proposed regression formula presented in this study.

Voxel-based morphometry and stereology provide convergent evidence of the importance of medial prefrontal cortex for fluid intelligence in healthy adults

We investigated whether a relationship exists between frontal lobe volume and fluid intelligence as measured by both Cattell's Culture Fair test and the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Performance scale, but not with crystallized intelligence as measured by the WAIS-R Verbal scale, in healthy adults, using two well-established image analysis techniques applied to high-resolution MR brain images. Firstly, using voxel-based morphometry (VBM), we investigated whether a significant relationship exists between gray matter concentration and fluid intelligence on a voxel-by-voxel basis. Secondly, we applied the Cavalieri method of modern design stereology in combination with point counting to investigate possible relationships between macroscopic volumes of relevant brain regions defined as dorsolateral, dorsomedial, orbitolateral, and orbitomedial prefrontal cortex on the basis of neuroanatomical landmarks, and fluid intelligence. We also examined the effect on these relationships of normalizing regional brain volumes to intracranial volume. VBM analysis revealed a positive correlation between gray matter concentration in the medial region of prefrontal cortex and Culture Fair scores (corrected for multiple comparisons), and also WAIS-R Performance Intelligence sum of scaled scores (SSS) (uncorrected for multiple comparisons before controlling for age, and this converges with the stereological finding of the positive correlation between volume of dorsomedial prefrontal cortex normalized to intracranial volume and Culture Fair scores after controlling for age. WAIS-R Verbal Intelligence SSS showed no correlations. We interpret our findings, from independent analyses of both VBM and stereology, as evidence of the importance of medial prefrontal cortex in supporting fluid intelligence.

Recommendations from Gynaecological (GYN) GEC-ESTRO Working Group (I): concepts and terms in 3D image based 3D treatment planning in cervix cancer brachytherapy with emphasis on MRI assessment of GTV and CTV

BACKGROUND AND PURPOSE

Brachytherapy (BT) plays a crucial role in the management of invasive cervix cancer from stage I to IV. Intracavitary techniques are based on afterloading devices, with different types of applicators. CT and/or MRI compatible applicators allow a sectional image based approach with a better assessment of gross tumour volume (GTV) and definition and delineation of target volume (CTV) compared to traditional approaches. Accurate and reproducible delineation of GTV, CTV and PTV, as well as of critical organs has a direct impact on BT treatment planning, especially if it is possible to adapt the pear-shape isodose by optimisation using DVH analysis. When introducing a 3D image based approach for GTV and CTV assessment, there is a need for a common language to describe the concepts and to define the terms which are to be used.

METHODS

In 2000, GEC-ESTRO decided to support 3D imaging based 3D treatment planning approach in cervix cancer BT with the creation of a Working Group. The task was to describe basic concepts and terms and to work out a terminology enabling various groups working in this advanced field to use a common language. The recommendations described in this report were proposed based on clinical experience and dosimetric concepts of different institutions (IGR, Leuven, Vienna) and were stepwise validated against the background of different clinical experience.

CONCLUSIONS

As GTV and CTV for BT change significantly during treatment, time frame for assessment of GTV and CTV for BT is specified in this report: at time of diagnosis GTV(D), CTV(D) and at time of BT GTV(B), CTV(B). Furthermore, CTV for BT is defined related to risk for recurrence: high risk CTV and intermediate risk CTV. Beside verbal descriptions detailed examples are given, partly in form of schematic drawings.

Assessment of tumor regression by consecutive pelvic magnetic resonance imaging and dose modification during high-dose-rate brachytherapy for carcinoma of the uterine cervix

PURPOSE

To assess tumor regression, as determined by pelvic magnetic resonance imaging (MRI), and evaluate the efficacies and toxicities of the interim brachytherapy (BT) modification method, according to tumor regression during multi-fractionated high-dose-rate (HDR) BT for uterine cervical cancer.

MATERIALS AND METHODS

Consecutive MRI studies were performed pre-radiotherapy (RT), pre-BT and during interfraction of BT (inter-BT) in 69 patients with cervical cancer. External beam radiotherapy (EBRT) was performed, using a 10 MV X-ray, in daily fraction of 1.8 Gy with 4-fields, 5 d/wk. Radiation was delivered up to 50.4 Gy, with midline shielding at around 30.6 Gy. Of all 69 patients, 50 received modified interim BT after checking the inter-BT MRI. The BT was delivered in two sessions; the first was composed of several 5 Gy fractions to point A, twice weekly, using three channel applicators. According to the three measured orthogonal diameters of the regressed tumor, based on inter-BT MR images, the initial BT plan was modified, with the second session consisting of a few fractions of less than 5 Gy to point A, using a cervical cylinder applicator.

RESULTS

The numbers of patients in FIGO stages Ib, IIa, IIb and IIIb+IVa were 19 (27.5%), 18 (26.1%), 27 (39.2%) and 5 (7.2%), respectively. Our treatment characteristics were comparable to those from the literatures with respect to the biologically effective dose (BED) to point A, rectum and bladder as reference points. In the regression analysis a significant correlation was observed between tumor regression and the cumulative dose to point A on the follow-up MRI. Nearly 80% regression of the initial tumor volume occurred after 30.6 Gy of EBRT, and this increased to 90% after an additional 25 Gy in 5 fractions of BT, which corresponds to 73.6 Gy of cumulative BED(10) to point A. The median total fraction number, and those at the first and second sessions of BT were 8 (5 approximately 10), 5 (3 approximately 7) and 3 (1 approximately 5), respectively. The median follow-up time was 53 months (range, 9 approximately 66 months). The 4-year disease-free survival rate of all patients was 86.8%. Six (8.7%) patients developed pelvic failures, but major late complications developed in only two (2.9%).

CONCLUSION

Our study shows that effective tumor control, equivalent survival and low rates of major complications can be achieved by modifying the fraction size during BT according to tumor regression, as determined by consecutive MR images. We recommend checking the follow-up MRI at a cumulative BED(10) of around 65 Gy to point A, with the initial BT modified at a final booster BT session.

Conventional, conformal, and intensity-modulated radiation therapy treatment planning of external beam radiotherapy for cervical cancer: The impact of tumor regression

PURPOSE

Investigating the impact of tumor regression on the dose within cervical tumors and surrounding organs, comparing conventional, conformal, and intensity-modulated radiotherapy (IMRT) and the need for repeated treatment planning during irradiation.

METHODS AND MATERIALS

Fourteen patients with cervical cancer underwent magnetic resonance (MR) imaging before treatment and once during treatment, after about 30 Gy. Target volumes and critical organs were delineated. First conventional, conformal, and IMRT plans were generated. To evaluate the impact of tumor regression, we calculated dose-volume histograms for these plans, using the delineations of the intratreatment MR images. Second conformal and IMRT plans were made based on the delineations of the intratreatment MR images. First and second plans were compared.

RESULTS

The average volume receiving 95% of the prescribed dose (43 Gy) by the conventional, conformal, and IMRT plans was, respectively, for the bowel 626 cc, 427 cc, and 232 cc; for the rectum 101 cc, 90 cc, and 60 cc; and for the bladder 89 cc, 70 cc, and 58 cc. The volumes of critical organs at this dose level were significantly reduced using IMRT compared with conventional and conformal planning (p < 0.02 in all cases). After having delivered about 30 Gy external beam radiation therapy, the primary gross tumor volumes decreased on average by 46% (range, 6.1-100%). The target volumes on the intratreatment MR images remained sufficiently covered by the 95% isodose. Second IMRT plans significantly diminished the treated bowel volume, if the primary gross tumor volumes decreased >30 cc.

CONCLUSIONS

Intensity-modulated radiation therapy is superior in sparing of critical organs compared with conventional and conformal treatment, with adequate coverage of the target volumes. Intensity-modulated radiation therapy remains superior after 30 Gy external beam radiation therapy, despite tumor regression and internal organ motion. Repeated IMRT planning can improve the sparing of the bowel and rectum in patients with substantial tumor regression.

Detection and volume determination of colonic tumors in Min mice by magnetic resonance micro-imaging

We applied MRI to the in vivo detection of spontaneous colorectal tumors in a unique mouse model, the Fox Chase Cancer Center (FCCC) ApcMIN mouse. Unlike other Min (multiple intestinal neoplasia) strains, FCCC ApcMIN animals develop an appreciable number of tumors in the large intestine, which makes them an appropriate mouse model for colon cancer in humans. We describe a method for marking the colon on MRI data sets that involves a bowel-cleansing procedure and the insertion of a polyurethane tube (filled with an MRI contrast agent) fully into the colon. We found that tumors as small as 1.5 mm in diameter can be consistently identified from MRI datasets with a voxel size of 0.1 mm x 0.133 mm x 0.133 mm. Tumor volumes were determined from the MRM data sets with the use of a novel approach to planimetry in 3D data sets. We observed a correlation between tumor volume (as measured from the MRI datasets) and tumor weight of 0.942, and a P-value of 0.008, based on Spearman's test. These data show that MRI can be used to accurately monitor tumor growth in mouse models of colorectal carcinogenesis.

Stereology versus planimetry to estimate the volume of malignant liver lesions on MR imaging

Liver tumor volume measurements are clinically useful in patients undergoing cancer treatment. The techniques of planimetry and stereology were applied for this purpose on magnetic resonance (MR) imaging. Fifty-eight malignant liver lesions were depicted on MR images in 20 consecutive patients. The volume of all lesions was estimated using stereology technique, based on point counting. Stereological tumor volume estimations were compared with those determined by manual planimetry. The repeatability of both techniques was assessed. Tumor volumes estimated by the two techniques were highly correlated (r = 0.98, p < 0.0001). The 95% limits of agreement showed that the stereological volume estimations may differ from the planimetric assessments by less than 23%. Both techniques presented comparable intra- and interobserver variability. The planimetry was 1.5 times faster than the stereology. Both volumetric techniques may provide reliable and reproducible liver tumor volume estimations. The planimetry may be the method of choice because of its superior speed.

Quantification of tumour response to radiotherapy

In 1979, the World Health Organization (WHO) established criteria based on tumour volume change for classifying response to therapy as (i) progressive disease (PD), (ii) partial recovery (PR), and (iii) no change (NC). Typically, the tumour volume is reported from diameter measurements, using the calliper method. Alternatively, the Cavalieri method provides unbiased volume estimates of any structure without assumptions about its shape. In this study, we applied the Cavalieri method in combination with point counting to investigate the changes in tumour volume in four patients with high grade glioma, using 3D MRI. In particular, the volume of tumour within the enhancement boundary, the enhancing abnormality (EA), was estimated from T(1) weighted images, and the volume of the non-enhancing abnormality, (NEA) enhancing abnormality, was estimated from T(2) relaxation time and magnetic transfer ratio tissue characterization maps. We compared changes in tumour volume estimated by the Cavalieri method with those obtained using the calliper method. Absolute tumour volume differed significantly between the two methods. Analysis of relative change in tumour volume, based on the WHO criteria, provided a different classification using the calliper and Cavalieri methods. The benefit of the Cavalieri method over the calliper method in the estimation of tumour volume is justified by the following factors. First, Cavalieri volume estimates are mathematically unbiased. Second, the Cavalieri method is highly efficient under an appropriate sampling density (i.e. EA volume estimates can be obtained with a coefficient of error no higher than 5% in 2-3 min). Third, the source of variation of the volume estimates due to disagreements between observers, and within observer, is much greater in the positioning of the calliper diameters than in the identification of the tumour boundaries when applying the Cavalieri method. Additionally, the error prediction formula, available to estimate the coefficient of error of Cavalieri volume estimates from the data, allows us to establish more precise classification criteria against which to identify potentially clinical significant changes in tumour volume.

The impact of sectional imaging on dose escalation in endocavitary HDR-brachytherapy of cervical cancer: results of a prospective comparative trial

PURPOSE

The purpose of this comparative prospective study was to assess the effect of CT and MR based individualisation and adaptation on the dose distribution in the target volume and organs at risk compared to a radiography based procedure.

MATERIAL AND METHODS

In 15 patients MR scans, in 10 patients additional axial CT-scans with compatible tube-ring applicator in situ were performed and digitally transferred to the PLATO(R) planning system. Considering clinical examination and MR-scan before radiotherapy individual 3-D dose distribution was calculated and adapted based on (1) two orthogonal radiographs; (2) isodoses superimposed on the CT images; and (3) isodoses superimposed on the MR images. Adaptation was strictly limited by the dose level at 2 cm(3) bladder or rectum volume (D(2)) to allow comparison of CT and MR plans. All three individualised dose distributions were superimposed on the MR images and cumulative dose-volume histograms were calculated for comparison.

RESULTS

3-D individualisation based on sectional imaging enabled higher dose to the target volume (isodose enclosing 95% of the CTV=CTV(95)) compared to individualised treatment plans based on orthogonal radiographs by a mean factor of 1.2 (1-1.7). The dose to bladder and/or rectum wall was at the same time not increased beyond the prescribed tolerance level (71% of the prescribed target dose). In a subgroup of 10 patients MRI based treatment plans were superior to CT based treatment plans allowing for a higher dose (138% vs. 124%).

CONCLUSION

Sectional imaging based treatment planning, in particular using MR, was superior to radiography allowing for a clinical meaningful dose escalation without increasing the dose to bladder and rectum beyond the tolerance level.

Magnetic resonance cystometry: accurate assessment of bladder volume with magnetic resonance imaging

OBJECTIVES

To evaluate magnetic resonance hydrometry for the calculation of bladder volume. The reference standard to assess bladder volume is urethral catheterization, which may be linked with the risk of trauma and infection. Hence, ultrasonography is the preferred diagnostic method. However, ultrasonography is investigator dependent and inaccurate in the hands of an inexperienced operator.

METHODS

Investigations were performed in a 1.0-Tesla clinical scanner with a manufacturer-provided single-shot turbo spin-echo sequence. We examined 30 healthy volunteers (21 males and 9 females) with a mean age of 26.4 years. To quantify the volume of fluid in a magnetic resonance image, a histogram algorithm was used and a calibration phantom applied. Prevoid and postvoid images were acquired. The bladder volume was calculated as the difference between the prevoid and postvoid image fluid volumes. The magnetic resonance-calculated data were compared with the actually voided volumes.

RESULTS

The measured voided bladder volume was 400 +/- 33 mL, whereas magnetic resonance hydrometry yielded 390 +/- 31 mL. The difference between both measurements was not statistically significant. The 95% confidence interval for the difference of both measurements ranged from -22.6 to 2.4 mL. The regression had an r2 of 0.97.

CONCLUSIONS

The feasibility of magnetic resonance hydrometry to quantify the bladder volume noninvasively was demonstrated.

Comparison of two volumetric techniques for estimating liver volume using magnetic resonance imaging

PURPOSE

To compare the conventional technique of manual planimetry with the point counting technique for estimating liver volume from magnetic resonance imaging (MRI) data.

MATERIALS AND METHODS

This study comprised abdominal MR examinations of 38 consecutive patients. Evaluation of the images showed that liver size appeared normal in 27 patients and increased in 11. Liver volume was estimated using the techniques of planimetry and point counting. Both techniques were used in combination with the Cavalieri method of modern design stereology. A systematic slice sampling procedure was performed to estimate liver volumes using both volumetric techniques. The point counting technique was optimized by altering the point spacing of the grid. The agreement between the two techniques was found. Measurement repeatability of both volumetric techniques was also evaluated.

RESULTS

Both techniques allowed the same degree of optimization through the procedure of systematic section sampling. The application of a point spacing of 2.5 cm reduced the time measurement by a factor of 3.5 in relation with the time needed with planimetry. An excellent agreement was observed between the two volumetric techniques with mean differences (+/-SD) of 2.4 +/- 41.6 cm(3) and 8.5 +/- 49.8 cm(3) for the patients presenting normal and increased liver sizes, respectively. Both techniques were highly reproducible.

CONCLUSION

The point counting technique could be considered a more efficient approach than planimetry for estimating liver volume from MRI, due to its speed and simplicity.

Postprandial decrease in splenic volume demonstrated by magnetic resonance imaging and stereology

The aim of this study was to determine if the volume of the spleen changes after food intake. We applied an unbiased and efficient method for splenic volume estimation using magnetic resonance imaging (MRI) in combination with modern design stereology. MR images of the spleen were obtained for 10 healthy volunteers (five men and five women; mean age 28.9 years [range 23-35 years]) without a history of splenomegaly. The initial scans were performed in the morning after overnight fasting. Each volunteer then consumed a standard balanced meal weighing 500 g [2,460 kJ (627 kcal) energy] with 500 ml of still mineral water. Second identical MR scans were performed approximately 1 hr later. Postprandially, splenic volume decreased by an average of 6.6% (P = 0.005), probably due to increased splanchnic blood flow after food intake.

Estimation of body composition in muscular dystrophy by MRI and stereology

We have applied the Cavalieri method of modern design stereology with magnetic resonance imaging for estimating the volume of whole-body muscle and fat compartments in four patients with muscular dystrophy, a patient with myopathy, five controls, an anorexic subject, and a body builder. Detailed systematic series (ie, 50) of axial MR images (T1-weighted, TR/TE 400/10 msec) were obtained throughout the whole body of each subject. The results showed that 15, 20, and 35 axial sections through the body are sufficient to secure coefficients of error (CEs) on the estimates of total muscle and fat volume of around 10%, 5%, and 3% respectively in muscular dystrophy patients and controls. The mean normalized volumes of muscle in four muscular dystrophy patients were decreased by 27% (t-test: P < 0.05), and those of total fat were increased by 12% (t-test: P > 0.05) relative to controls. The Cavalieri method provides a direct, efficient, and mathematically unbiased approach for studying human body compartments and may have application in assessing treatment efficacy in patients with muscular dystrophy. J. Magn. Reson. Imaging 2000;12:467-475.

[Role of laparoscopy in the management of uterine cervix cancer]

At the turn of this century, the evidence of the benefits of a concurrent chemo-radiotherapy in locally advanced tumors and the development of mini-invasive surgery (laparoscopic and radical vaginal surgery) are the two main advances in the management of cervical carcinomas. From a personal experience of 304 cervical carcinomas, the different techniques of laparoscopy used in cervical carcinomas are addressed and discussed. Their long-term results when involved in the management protocols of cervical carcinomas at different stages are reported. From this series, some conclusions are drawn: 1) laparoscopy can spare a laparotomy in early-stage node-negative patients with low tumoral volume; 2) it can spare a systematic extended-field radiation therapy in high-risk patients with node-negative para-aortic exploration; 3) it can spare surgery in patients with a centro-pelvic advanced stage or recurrence, possibly candidates for an exenterative procedure, if occult spread is found in the intra- or retroperitoneal areas. The more and more frequent combination of the mini-invasive surgery for staging and treatment and radiotherapy or chemotherapy explains the need for new protocols of a more and more complex and specialized management.

Contrast enhanced dynamic MRI of cervical carcinoma during radiotherapy: early prediction of tumour regression rate

This prospective study investigated the relationship between changes in the MRI dynamic enhancement of cervical carcinoma early during radiotherapy, and tumour regression rate throughout radiotherapy. A total of 36 MRI examinations was performed in seven patients with cervical carcinoma, including a T2 weighted sequence weekly during radiotherapy and also a multislice dynamic Gd-DTPA enhanced sequence before and after the first 2 weeks of radiotherapy. Tumour enhancement was determined on dynamic images using a region of interest and signal-to-noise ratio method. Serial tumour volumes over time on T2 weighted images were estimated using the Cavalieri method of modern design-based stereology to obtain tumour regression rate. It was found that peak and mean enhancement prior to radiotherapy ranged from 3.0 to 13.3, and from 1.9 to 12.2, respectively. After 2 weeks of radiotherapy, peak and mean enhancement ranged from 7.5 to 13.0, and from 6.3 to 10.6, respectively. The change in peak and mean tumour enhancement between dynamic scans ranged, respectively, from -2.0 to 8.4 and from -4.5 to 8.5. Tumour volume decreased exponentially with time (p < 0.01). Tumour regression rates ranged from 2.0% to 15.2% per day, and correlated positively with changes of both peak and mean tumour enhancement (p < 0.01). It is concluded that MRI dynamic enhancement during the first 2 weeks of radiotherapy may provide early prediction of tumour regression rate, and therefore be of value in designing treatment schedules for cervical carcinoma.