High-resolution MR imaging of stage I cervical neoplasia with a dedicated transvaginal coil: MR features and correlation of imaging and pathologic findings

An endovaginal MRI array with a forward-looking coil for advanced gynecological cancer brachytherapy procedures: Design and initial results

PURPOSE

To develop an endovaginal MRI array that provides signal enhancement forward into the posterior parametrium and sideways into the vaginal wall, accelerating multiple-contrast detection of residual tumors that survive external beam radiation. The array's enclosure should form an obturator for cervical cancer brachytherapy, allowing integration with MRI-guided catheter placement, CT, and interstitial radiation dose delivery.

METHODS

The endovaginal array consisted of forward-looking and sideways-looking components. The forward-looking element imaged the cervix and posterior endometrium, and the sideways-looking elements imaged the vaginal wall. Electromagnetic simulation was performed to optimize the geometry of a forward-looking coil placed on a conductive-metallic substrate, extending the forward penetration above the coil's tip. Thereafter, an endovaginal array with one forward-looking coil and four sideways-looking elements was constructed and tested at 1.5 Tesla in saline and gel phantoms, and three sexually mature swine. Each coil's tuning, matching, and decoupling were optimized theoretically, implemented with electronic circuits, and validated with network-analyzer measurements. The array enclosure emulates a conventional brachytherapy obturator, allowing use of the internal imaging array together with tandem coils and interstitial catheters, as well as use of the enclosure alone during CT and radiation delivery. To evaluate the receive magnetic field ( B 1 - ) spatial profile, the endovaginal array's specific absorption-rate (SAR) distribution was simulated inside a gel ASTM phantom to determine extreme heating locations in advance of a heating test. Heating tests were then performed during high SAR imaging in a gel phantom at the predetermined locations, testing compliance with MRI safety standards. To assess array imaging performance, signal-to-noise-ratios (SNR) were calculated in a saline phantom and in vivo. Swine images were acquired with the endovaginal array combined with the scanner's body and spine arrays.

RESULTS

Simulated B 1 - profiles for the forward-looking lobe pattern, obtained while varying several geometric parameters, disclosed that a forward-looking coil placed on a metal-backed substrate could double the effective forward penetration from approximately 25 to ∼40 mm. An endovaginal array, enclosed in an obturator enclosure was then constructed, with all coils tuned, matched, and decoupled. The ASTM gel-phantom SAR test showed that peak local SAR was 1.2 W/kg in the forward-looking coil and 0.3 W/kg in the sideways-looking elements, well within ASTM/FDA/IEC guidelines. A 15-min 4 W/kg average SAR imaging experiment resulted in less than 2^o C temperature increase, also within ASTM/FDA/IEC heating limits. In a saline phantom, the forward-looking coil and sideways-looking array's SNR was four to eight times, over a 20-30 mm field-of-view (FOV), and five to eight times, over a 15-25 mm FOV, relative to the spine array's SNR, respectively. In three sexually mature swine, the forward-looking coil provided a 5 + 0.2 SNR enhancement factor within the cervix and posterior endometrium, and the sideways-looking array provided a 4 + 0.2 SNR gain factor in the vaginal wall, relative to the Siemens spine array, demonstrating that the array could significantly reduce imaging time.

CONCLUSIONS

Higher SNR gynecological imaging is supported by forward-looking and sideways-looking coils. A forward-looking endovaginal coil for cervix and parametrium imaging was built with optimized metal backing. Array placement within an obturator enhanced integration with the brachytherapy procedure and accelerated imaging for detecting postexternal-beam residual tumors.

Imaging to assist fertility-sparing surgery

Cytological screening and human papilloma virus testing has led to diagnosis of cervical cancer in young women at an earlier stage. Defining the full extent of the disease within the cervix with imaging aids the decision on feasibility of fertility-sparing surgical options, such as extended cone biopsy or trachelectomy. High spatial resolution images with maximal contrast between tumour and surrounding background are achieved with T2-weighted and diffusion-weighted (DW) magnetic resonance imaging (MRI) obtained using an endovaginal receiver coil. Tumour size and volume demonstrated in this way correlates between observers and with histology and differences between MRI and histology estimates of normal endocervical canal length are not significant. For planning fertility-sparing surgery, this imaging technique facilitates the best oncological outcome while minimising subsequent obstetric risks. Parametrial invasion may be assessed on large field of view T2-weighted MRI. The fat content of the parametrium limits the utility of DW imaging in this context, because fat typically shows diffusion restriction. The use of contrast-enhanced MRI for assessing the parametrium does not provide additional benefits to the T2-weighted images and the need for an extrinsic contrast agent merely adds additional complexity and cost. For nodal assessment, 18fluorodeoxyglucose positron emission tomography-computerised tomography (18FDG PET-CT) remains the gold standard.

Proton MRS of cervical cancer at 7 T

The differentiation grade of cervical cancer is histologically assessed by examining biopsies or surgical specimens. MRS is a highly sensitive technique that images tissue metabolism and can be used to increase the specificity of tissue characterization in a non-invasive manner. We aim to explore the feasibility of using in vivo ¹ H-MRS at 7 T in women with cervical cancer to study tissue fatty acid composition. 10 women with histologically proven Stage IB1-IIB cervical cancer were scanned with a whole-body 7 T MR system with a multi-transmit system and an internal receive only monopole antenna. A STEAM sequence was used to obtain ¹ H-MRS data. Fatty acid resonances were fitted with Lorentzian curves and the 2.1 ppm/1.3 ppm ratios were calculated. ¹ H-MRS data showed fatty acid signals resonating at 2.1 ppm, 1.9 ppm, 1.5 ppm, 1.3 ppm and 0.9 ppm. Mean 2.1/1.3 ppm ratios were 0.019 ± 0.01, 0.021 ± 0.006, 0.12 ± 0.089 and 0.39 ± 0.27 for normal, Grade I, Grade II and Grade III groups respectively. Poorly differentiated tumor tissue (Grade III) showed elevated fatty acid ratios when compared with the well differentiated tumor (Grade I) or normal tissue. ¹ H-MRS in cervical cancer at 7 T is feasible and individual fatty acid signals were detected. In addition, poorly differentiated tumors show more fatty acid unsaturation. The 2.1 ppm/1.3 ppm ratio has potential for tumor characterization in a non-invasive manner for uterine cervical cancer.

Agreement Between Magnetic Resonance Imaging and Pathologic Findings in the Tumor Size Evaluation Before and After Neoadjuvant Chemotherapy Treatment: A Prospective Study

Objectives

To compare the agreement between magnetic resonance imaging (MRI) results and postsurgical pathologic findings for tumor size evaluation in cervical cancer patients before and after neoadjuvant chemotherapy (NACT) treatment.

Methods

The study analyzed the agreement between pretreatment MRI results and postsurgical pathologic findings about the tumor size in 100 cervical cancer patients without NACT and 397 cervical cancer patients with NACT, respectively.

Results

In general, the agreement between pretreatment MRI results and postsurgical pathologic findings of tumor size was 0.855 (95% confidence interval [CI], 0.763–0.909) in cervical cancer patients without NACT, whereas the agreement between posttreatment MRI results and postsurgical pathologic findings was 0.503 (95% CI, 0.421–0.576). Only 62.72% (249/397) of patients who underwent NACT treatment have the same chemotherapy response evaluation results; the κ coefficient was 0.384(95% CI, 0.310–0.457) between posttreatment MRI and postsurgical pathologic findings. We still found International Federation of Gynecology and Obstetrics stage is associated with the chemotherapy response evaluation.

Conclusions

Our data suggest that pretreatment MRI can be a surrogate indicator for postsurgical pathologic findings. However, posttreatment MRI could not be a surrogate indicator for postsurgical pathologic findings. The chemotherapy response evaluation based on only MRI is not so reliable. More indicators should be developed for chemotherapy response evaluation.

Volumetry of the dominant intraprostatic tumour lesion: intersequence and interobserver differences on multiparametric MRI

OBJECTIVE

To establish the interobserver reproducibility of tumour volumetry on individual multiparametric (mp) prostate MRI sequences, validate measurements with histology and determine whether functional to morphological volume ratios reflect Gleason score.

METHODS

41 males with prostate cancer treated with prostatectomy (Cohort 1) or radical radiotherapy (Cohort 2), who had pre-treatment mpMRI [T2 weighted (T2W) MRI, diffusion-weighted (DW)-MRI and dynamic contrast-enhanced (DCE)-MRI], were studied retrospectively. Dominant intraprostatic lesions (DIPLs) were manually delineated on each sequence and volumes were compared between observers (n = 40 analyzable) and with radical prostatectomy (n = 20). Volume ratios of DW-MRI and DCE-MRI to T2W MRI were documented and compared between Gleason grade 3 + 3, 3 + 4 and 4 + 3 or greater categories.

RESULTS

Limits of agreement of DIPL volumes between observers were: T2W MRI 0.9, -1.1 cm3, DW-MRI 1.3, -1.7 cm3 and DCE-MRI 0.74, -0.89 cm3. In Cohort 1, T2W volumes overestimated fixed specimen histological volumes (+33% Observer 1, +16% Observer 2); DW- and DCE-MRI underestimated histological volume, the latter markedly so (-32% Observer 1, -79% Observer 2). Differences between T2W, DW- and DCE-MRI volumes were significant (p < 10-8). The ratio of DW-MRI volume (73.9 ± 18.1% Observer 1, 72.5 ± 21.9% Observer 2) and DCE-MRI volume (42.6 ± 24.6% Observer 1, 34.3 ± 24.9% Observer 2) to T2W volume was significantly different (p < 10-8), but these volume ratios did not differ between the Gleason grades.

CONCLUSION

The low variability of the DIPL volume on T2W MRI between Observers and agreement with histology indicates its suitability for delineation of gross tumour volume for radiotherapy planning. The volume of cellular tumour represented by DW-MRI is greater than the vascular (DCE) abnormality; ratios of both to T2W volume are independent of Gleason score. Advances in knowledge: (1) Manual volume measurement of tumour is reproducible within 1 cm3 between observers on all sequences, confirming suitability across observers for radiotherapy planning. (2) Volumes derived on T2W MRI most accurately represent in vivo lesion volumes. (3) The proportion of cellular (DW-MRI) or vascular (DCE-MRI) volume to morphological (T2W MRI) volume is not affected by Gleason score.

Separation of type and grade in cervical tumours using non-mono-exponential models of diffusion-weighted MRI

OBJECTIVES

Assessment of empirical diffusion-weighted MRI (DW-MRI) models in cervical tumours to investigate whether fitted parameters distinguish between types and grades of tumours.

METHODS

Forty-two patients (24 squamous cell carcinomas, 14 well/moderately differentiated, 10 poorly differentiated; 15 adenocarcinomas, 13 well/moderately differentiated, two poorly differentiated; three rare types) were imaged at 3 T using nine b-values (0 to 800 s mm-2). Mono-exponential, stretched exponential, kurtosis, statistical, and bi-exponential models were fitted. Model preference was assessed using Bayesian Information Criterion analysis. Differences in fitted parameters between tumour types/grades and correlation between fitted parameters were assessed using two-way analysis of variance and Pearson's linear correlation coefficient, respectively.

RESULTS

Non-mono-exponential models were preferred by 83 % of tumours with bi-exponential and stretched exponential models preferred by the largest numbers of tumours. Apparent diffusion coefficient (ADC) and diffusion coefficients from non-mono-exponential models were significantly lower in poorly differentiated tumours than well/moderately differentiated tumours. α (stretched exponential), K (kurtosis), f and D* (bi-exponential) were significantly different between tumour types. Strong correlation was observed between ADC and diffusion coefficients from other models.

CONCLUSIONS

Non-mono-exponential models were preferred to the mono-exponential model in DW-MRI data from cervical tumours. Parameters of non-mono-exponential models showed significant differences between types and grades of tumours.

KEY POINTS

• Non-mono-exponential DW-MRI models are preferred in the majority of cervical tumours. • Poorly differentiated cervical tumours exhibit lower diffusion coefficients than well/moderately differentiated tumours. • Non-mono-exponential model parameters α, K, f, and D* differ between tumour types. • Micro-structural features are likely to affect parameters in non-mono-exponential models differently.

High-resolution T2-weighted cervical cancer imaging: a feasibility study on ultra-high-field 7.0-T MRI with an endorectal monopole antenna

Objectives

We studied the feasibility of high-resolution T₂-weighted cervical cancer imaging on an ultra-high-field 7.0-T magnetic resonance imaging (MRI) system using an endorectal antenna of 4.7-mm thickness.

Methods

A feasibility study on 20 stage IB1–IIB cervical cancer patients was conducted. All underwent pre-treatment 1.5-T MRI. At 7.0-T MRI, an external transmit/receive array with seven dipole antennae and a single endorectal monopole receive antenna were used. Discomfort levels were assessed. Following individualised phase-based B₁⁺ shimming, T₂-weighted turbo spin echo sequences were completed.

Results

Patients had stage IB1 (n = 9), IB2 (n = 4), IIA1 (n = 1) or IIB (n = 6) cervical cancer. Discomfort (ten-point scale) was minimal at placement and removal of the endorectal antenna with a median score of 1 (range, 0–5) and 0 (range, 0–2) respectively. Its use did not result in adverse events or pre-term session discontinuation. To demonstrate feasibility, T₂-weighted acquisitions from 7.0-T MRI are presented in comparison to 1.5-T MRI. Artefacts on 7.0-T MRI were due to motion, locally destructive B₁ interference, excessive B₁ under the external antennae and SENSE reconstruction.

Conclusions

High-resolution T₂-weighted 7.0-T MRI of stage IB1–IIB cervical cancer is feasible. The addition of an endorectal antenna is well tolerated by patients.

Key Points

• High resolution T₂-weighted 7.0-T MRI of the inner female pelvis is challenging

• We demonstrate a feasible approach for T₂-weighted 7.0-T MRI of cervical cancer

• An endorectal monopole receive antenna is well tolerated by participants

• The endorectal antenna did not lead to adverse events or session discontinuation

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-016-4419-y) contains supplementary material, which is available to authorized users.

Comparison of optimised endovaginal vs external array coil T2-weighted and diffusion-weighted imaging techniques for detecting suspected early stage (IA/IB1) uterine cervical cancer

OBJECTIVE

To compare sensitivity and specificity of endovaginal versus external-array coil T2-W and T2-W + DWI for detecting and staging small cervical tumours.

METHODS

Optimised endovaginal and external array coil MRI at 3.0-T was done prospectively in 48 consecutive patients with stage Ia/Ib1 cervical cancer. Sensitivity/specificity for detecting tumour and parametrial extension against histopathology for a reading radiologist were determined on coronal T2-W and T2W + DW images. An independent radiologist also scored T2-W images without and with addition of DWI for the external-array and endovaginal coils on separate occasions >2 weeks apart. Cohen's kappa assessed inter- and intra-observer agreement.

RESULTS

Median tumour volume in 19/38 cases positive on subsequent histology was 1.75 cm(3). Sensitivity, specificity, PPV, NPV were: reading radiologist 91.3 %, 89.5 %, 91.3 %, 89.5 %, respectively; independent radiologist T2-W 82.6 %, 73.7 %, 79.1 %, 77.8 % for endovaginal, 73.9 %, 89.5 %, 89.5 %, 73.9 % for external-array coil. Adding DWI improved sensitivity and specificity of endovaginal imaging (78.2 %, 89.5 %); adding DWI to external-array imaging improved specificity (94.7 %) but reduced sensitivity (66.7 %). Inter- and intra-observer agreement on T2-W + DWI was good (kappa = 0.67 and 0.62, respectively).

CONCLUSION

Endovaginal coil T2-W MRI is more sensitive than external-array coil for detecting tumours <2 cm(3); adding DWI improves specificity of endovaginal imaging but reduces sensitivity of external-array imaging.

KEY POINTS

• Endovaginal more accurate than external-array T2-W MRI for detecting small cervical cancers. • Addition of DWI improves sensitivity and specificity of endovaginal T2-W imaging. • Addition of DWI substantially reduces sensitivity of external-array T2-W imaging.

Quantification of delineation errors of the gross tumor volume on magnetic resonance imaging in uterine cervical cancer using pathology data and deformation correction

BACKGROUND

To safely optimize target volumes using magnetic resonance imaging (MRI) for uterine cervical cancer radiation therapy, MRI findings need to be validated. The aim of this study was to correlate pre-operatively acquired MRI and surgical specimen imaging for uterine cervical cancer patients using deformable image registration and quantify gross tumor volume (GTV) delineation discrepancies.

MATERIAL AND METHODS

For 16 retrospectively selected early-stage uterine cervical cancer patients, the cervix-uterus structure, uterine cavity and the GTV were delineated on 2D pathology photos after macroscopic intersection and corresponding pre-operatively acquired T2-weighted 2D sagittal MR images. Segmentations of pathology photos and MR images were simultaneously registered using a three-step multi-image registration strategy. The registration outcome was evaluated by the Dice similarity coefficient (DSC) and the surface distance error (SDE). In addition, GTV expansions within the cervix-uterus structure needed to obtain 95% GTV coverage were determined.

RESULTS

After three-step multi-image registration, the median DSC and median SDE were 0.98 and 0.4 mm (cervix-uterus) and 0.90 and 0.4 mm (uterine cavity), respectively. The average SDE around the GTV was 0.7 mm (range, 0.1 mm - 2.6 mm). An underestimation of MRI-based GTV delineations was found when no margin was applied, indicated by a mean GTV coverage of 61%. To obtain 95% GTV coverage for 90% of the patients, a minimum 12.0 mm margin around MRI-based GTVs was needed.

CONCLUSION

The presented three-step multi-image registration strategy was suitable and accurate to correlate MRI and pathology data for uterine cervical cancer patients. To cover the pathology-based GTV, a margin of at least 12.0 mm around GTV delineations on T2-weighted MRI is needed.

Magnetic resonance imaging of cervical carcinoma using an endorectal surface coil

INTRODUCTION

The objective of this trial is to investigate the diagnostic value of magnetic resonance imaging (MRI) with an endorectal surface coil for precise local staging of patients with histologically proven cervical cancer by comparing the radiological, clinical, and histological results.

MATERIALS AND METHODS

Women with cervical cancer were recruited for this trial between February 2007, and September 2010. All the patients were clinically staged according to the FIGO classification and underwent radiological staging by MRI that employed an endorectal surface coil. The staging results after surgery were compared to histopathology in all the operable patients.

RESULTS

A total of 74 consecutive patients were included in the trial. Forty-four (59.5%) patients underwent primary surgery, whereas 30 (40.5%) patients were inoperable according to FIGO and underwent primary radiochemotherapy. The mean age of the patients was 50.6 years. In 11 out of the 44 patients concordant staging results were obtained by all three staging modalities. Thirty-two of the 44 patients were concordantly staged by FIGO and histopathological examination, while only 16 were concordantly staged by eMRI and histopathological examination. eMRI overstaged tumors in 14 cases and understaged them in 7 cases.

CONCLUSIONS

eMRI is applicable in patients with cervical cancer, yet of no benefit than staging with FIGO or standard pelvic MRI. The most precise preoperative staging procedure still appears to be the clinical examination.

Preoperative imaging in patients undergoing trachelectomy for cervical cancer: validation of a combined T2- and diffusion-weighted endovaginal MRI technique at 3.0 T

AIM

The aim of this study is to validate high-resolution endovaginal T2- and diffusion-weighted MRI measurements (tumour size, volume and length of uninvolved cervical canal) against histology in patients undergoing trachelectomy.

PATIENTS/INTERVENTIONS

55 consecutive patients 25-44 years with cervical cancer being considered for trachelectomy were prospectively assessed with endovaginal T2-W and diffusion-weighted MRI. Two independent observers blinded to histology recorded maximum tumour dimension, volume and distance from the superior aspect of the tumour to the internal os. Following trachelectomy, pathologist-outlined tumour sections were photographed with a set scale and similar measurements were recorded.

RESULTS

Fifteen of 45 patients subsequently treated with fertility-sparing surgery had residual tumour (median histological volume: 0.28 cm(3), IQR=0.14-1.06 cm(3)). Sensitivity, specificity, positive and negative predictive values for detecting tumour: Observer 1: 86.7%, 80.0%, 68.4%, and 92.3%, respectively; Observer 2: 86.7%, 90.0%, 81.0%, and 93.1%, respectively. Size and volume correlated between observers (r=0.96, 0.84, respectively, p<0.0001). Size correlated between each observer and histology (observer 1 r=0.91, p<0.0001; observer 2 r=0.93, p<0.0001), volume did not (observer 1: r=0.08, p=0.6; observer 2: r=0.21, p=0.16); however, differences between observer measurements and histology were not significant (size p=0.09, volume p=0.15). Differences between MRI and histology estimates of endocervical canal length were not significant (p=0.1 both observers).

CONCLUSION

In subcentimetre cervical cancers, endovaginal MRI correlates with pathology and is invaluable in assessing patients for fertility-sparing surgery.

Influencing surgical management in patients with carcinoma of the cervix using a T2- and ZOOM-diffusion-weighted endovaginal MRI technique

BACKGROUND

Endovaginal MRI (evMRI) at 3.0-T with T2-weighted (T2-W) and ZOnal Oblique Multislice (ZOOM)-diffusion-weighted imaging (DWI) potentially improves the detection of stage Ia/Ib1 cervical cancer. We aimed to determine its sensitivity/specificity, document tumour-to-stromal contrast and establish the effect of imaging on surgical management.

METHODS

Following ethical approval and written informed consent, 57 consecutive patients with suspected stage Ia/Ib1 cervical cancer underwent evMRI at 3.0-T using T2-W and ZOOM-DWI. Sensitivity/specificity were calculated against histopathology for two independent observers. Tumour-to-stromal contrast was determined on T2-W, and diffusion-weighted (b=800 s mm(-2)) images and apparent diffusion coefficients (ADCs) were recorded. In patients due for radical vaginal trachelectomy (RVT), change of surgical management based on imaging findings was documented.

RESULTS

Sensitivity/specificity for detecting tumour was the following: reporting read 88.0/81.8%, anonymised read 92.0/81.8% (observer 1); 84.0/72.7% (observer2; median tumour volume=1.7 cm(3)). Intraobserver agreement was excellent (kappa=0.89) and the interobserver agreement was good (kappa=0.65). Tumour-to-stromal contrast was greater on ZOOM-DWI compared with T2-W images (3.35±2.36 vs 1.39±0.95; P<0.0004). Tumour and stromal ADCs were significantly different (P<0.00001). In 31 patients due for RVT, evMRI altered surgical management in 12 (38.7%) cases (10 cone-biopsy, 2 chemoradiotherapy).

CONCLUSION

T2-W+ZOOM-DWI evMRI has high sensitivity/specificity for detecting stage Ia/Ib1 cervical tumours; in patients due for RVT, the surgical management was altered in ∼39%.

New MR techniques in gynecologic cancer

OBJECTIVE

Functional MR techniques report on a variety of biologic features of tumors: dynamic contrast-enhanced, diffusion-weighted, and intrinsic susceptibility-weighted MRI and MR spectroscopy reflect, at a simplistic level, vascularity, cellularity, hypoxic status, and metabolism, respectively. This article reviews the evidence for each of the functional MR readouts to determine these clinical end points and thus influence the management of ovarian, endometrial, and cervical cancer.

CONCLUSION

These techniques may be implemented in gynecologic malignancies to detect, characterize, and stage tumors as well as potentially to predict the outcome and measure response to treatment.

Relationship between imaging biomarkers of stage I cervical cancer and poor-prognosis histologic features: quantitative histogram analysis of diffusion-weighted MR images

OBJECTIVE

The purpose of this study was to determine whether histogram analysis of apparent diffusion coefficient (ADC) values from diffusion-weighted MRI can be used to differentiate cervical tumors according to their histologic characteristics.

SUBJECTS AND METHODS

Sixty patients with International Federation of Gynecology stage I cervical cancer underwent MRI at 1.5 T with a 37-mm-diameter endovaginal coil. T2-weighted images (TR/TE, 2000-2368/90) followed by diffusion-weighted images (TR/TE, 2500/69; b values, 0, 100, 300, 500, and 800 s/mm(2)) were acquired. An expert observer drew regions of interest around a histologically confirmed tumor on ADC maps by referring to the T2-weighted images. Pixel-by-pixel ADCs were calculated with a monoexponential fit of data from b values of 100-800 s/mm(2), and ADC histograms were obtained from the entire tumor volume. An independent samples Student t test was used to compare differences in ADC percentile values, skew, and kurtosis between squamous cell carcinoma and adenocarcinoma, well or moderately differentiated and poorly differentiated tumors, and absence and presence of lymphovascular space invasion.

RESULTS

There was no statistically significant difference in ADC percentiles between squamous cell carcinoma and adenocarcinoma, but the median was significantly higher in well or moderately differentiated tumors (50th percentile, 1113 ± 177 × 10(-6) mm(2)/s) compared with poorly differentiated tumors (50th percentile, 996 ± 184 × 10(-6) mm(2)/s) (p = 0.049). Histogram skew was significantly less positive for adenocarcinoma compared with squamous cell carcinoma (p = 0.016) but did not differ between tumor grades. There was no significant difference between any parameter with regard to lymphovascular space invasion.

CONCLUSION

Median ADC is lower in poorly compared with well or moderately differentiated tumors, while lower histogram-positive skew in adenocarcinoma compared with squamous cell carcinoma is likely to reflect the glandular content of adenocarcinoma.

Endovaginal magnetic resonance imaging of stage 1A/1B cervical cancer with A T2- and diffusion-weighted magnetic resonance technique: effect of lesion size and previous cone biopsy on tumor detectability

OBJECTIVE

To evaluate the effects of previous cone biopsy and lesion size on detectability of stage 1a/1b cervical cancer using endovaginal T2- and diffusion-weighted magnetic resonance imaging.

METHODS

One hundred and thirteen patients with cervical tumor were imaged using an endovaginal coil with T2-weighted (T2-W) and diffusion-weighted single-shot echo-planar sequences; 85 managed surgically (58 with prior cone biopsy/LLETZ) were evaluated. T2-W images and ADC maps viewed simultaneously were scored positive or negative for tumor and compared with histology at surgery. MRI tumor volumes, maximum radiological and histological dimensions were recorded. ROC analysis determined the MRI volume with optimal sensitivity/specificity for identifying tumor in those without and with prior cone biopsy/LLETZ and the maximum histological dimension for correctly identifying tumor with MRI. Mean apparent diffusion coefficients (ADCs) from tumor and adjacent normal epithelium were compared.

RESULTS

Sensitivity and specificity for detecting tumor in those without (100%; 100% respectively) and with (80%; 78.9% respectively) prior cone biopsy/LLETZ were significantly different (p<0.001). Following cone biopsy/LLETZ, MRI tumor volume of 83 mm3 detected tumor with 80% sensitivity, 94.7% specificity; a 5.3mm maximal histological dimension was detected on MRI with 100% sensitivity, 100% specificity. Tumor ADCs were significantly lower (p<0.001) than paired normal epithelial tissue (median, 988×10(-6) mm2/s vs. 1564×10(-6) mm2/s) but neither tumor nor epithelial ADCs differed significantly between patients with or without prior cone biopsy/LLETZ (p=0.48 and 0.15, respectively).

CONCLUSIONS

Endovaginal MRI with T2- and diffusion-weighted sequences has significantly lower sensitivity and specificity for tumor detection following cone biopsy/LLETZ.

Evaluation of magnetic resonance diffusion and spectroscopy measurements as predictive biomarkers in stage 1 cervical cancer

OBJECTIVE

To establish whether ADC and total choline were significantly different between cervical tumors with different histological characteristics (type, degree of differentiation, presence or absence of lymphovascular invasion, lymph-node involvement) in order to establish their role as predictive biomarkers.

METHODS

62 patients with stage 1 cervical cancer were scanned at 1.5 T. T2-weighted imaging (TR/TE=4500/80 ms), to identify tumor and normal cervix, was followed by diffusion-weighted imaging (TR/TE=2500/69 ms; 5 b-values 0, 100, 300, 500 and 800 s/mm(2)) and MR spectroscopic imaging (15 mm slice, 7.5 mm in-plane resolution, TR=888 ms). Regions of interest in normal cervix and tumor were drawn on apparent diffusion coefficient (ADC) maps by an expert observer with reference to the T2-weighted images. ADCs were calculated using a monoexponential fit of data from all b-values. MR spectra in voxels designated as tumor (>30% tumor) or non-tumor were quantified using LCModel and referenced to tissue water.

RESULTS

There was a statistically significant difference between the ADC of tumor regions (1117+/-183x10(-6) mm(2)/s) and of selected normal regions (1724+/-198x10(-6) mm(2)/s; p<0.001), and between tumors that were well/moderately differentiated (1196+/-181x10(-6) mm(2)/s) compared with those that were poorly differentiated (1038+/-153x10(-6) mm(2)/s; p=0.016). There was no significant difference between the ADCs of the tumors when separated by other characteristics (tumor type, lymphovascular invasion, lymph-node metastases), or between measured total choline in any of the groups.

CONCLUSION

ADCs are lower in cancer compared to normal cervical tissue, with degree of tumor differentiation contributing to this difference.

Ressonância magnética no estadiamento dos tumores de colo uterino

O câncer de colo uterino é a maior causa de morte entre mulheres em todo o mundo, notadamente nos países em desenvolvimento. A Federação Internacional de Ginecologia e Obstetrícia preconiza o estadiamento durante o ato operatório, porém nos casos mais avançados a abordagem terapêutica não é cirúrgica. Nestes casos, o estadiamento, em geral, é feito com o exame clínico ginecológico e exames básicos de imagem. Entretanto, essa forma de abordagem não expressa a real extensão da doença e não inclui importantes fatores prognósticos como volume tumoral, invasão estromal e acometimento linfonodal. A ressonância magnética está sendo cada vez mais utilizada para este fim, pois nos estádios iniciais seu desempenho pode ser comparado aos achados intra-operatórios e nos estádios avançados se mostra superior em relação à avaliação clínica. A ressonância magnética apresenta excelente resolução para diversas densidades das estruturas pélvicas, não utiliza radiação ionizante, é confortável, melhora o estadiamento, permite a detecção precoce de recidiva e a identificação de fatores prognósticos fidedignos que contribuem na decisão e predição dos resultados terapêuticos, com excelente custo-efetividade. Este artigo tem como objetivo revisar os aspectos da ressonância magnética mais importantes no estadiamento desta doença.

Magnetic resonance imaging of uterine malignancies

Magnetic Resonance Imaging (MRI) is the criterion standard in the assessment and staging of uterine cancer because of the high tissue contrast between glandular lining and inner and outer muscle layers of the uterine corpus and cervix on T2-weighted scans. It is also an essential tool in monitoring treatment response and in assessing disease recurrence in these patients. The key to a successful examination lies in good patient preparation, use of antiperistaltic agents, and a meticulous scanning technique. Endometrial carcinomas are the most common uterine malignancy, occurring in a primarily postmenopausal population. Dynamic contrast-enhanced scans may be required in addition to T2-weighted images to assess the presence of myometrial invasion in this age group. Cervical cancers occur in a younger population and are readily assessed with T2-weighted imaging. Use of an endovaginal receiver coil allows high spatial resolution imaging of the cervix, which is particularly useful when assessing patients for fertility-sparing procedures such as trachelectomy. Uterine sarcomas are 1% to 3% of all uterine malignancies and usually arise from a mixture of homologous and heterologous elements. Rarely, lymphoma, small cell carcinoma and metastatic deposits involve the uterus. This review summarizes the optimal scanning techniques for demonstrating uterine malignancy and discusses the role of imaging and the MRI appearances of uterine tumors.

Cervical cancer: value of an endovaginal coil magnetic resonance imaging technique in detecting small volume disease and assessing parametrial extension

BACKGROUND

Estimation of tumor volume by endovaginal magnetic resonance (MR) imaging is a better indicator of prognosis than FIGO stage in women with cervical cancer treated by standard modalities. However, the introduction of fertility conserving surgical techniques makes fresh demands upon imaging of these small tumors.

OBJECTIVE

To determine the sensitivity and specificity of endovaginal MRI in detecting small volume disease and assessing parametrial extension in uterine cervical cancer by comparing the findings with those at radical hysterectomy in order to establish its role in guiding the surgical decision-making process preoperatively.

METHODS

A retrospective study was performed in 119 patients who underwent endovaginal and external phased array MR imaging at 0.5 T or 1.5 T before radical hysterectomy. Tumor presence within the cervix and parametrial extension was noted on the endovaginal images. Histopathological findings were correlated with MR imaging results for all patients.

RESULTS

The sensitivity and specificity for detecting tumor by endovaginal MR imaging in the 119 patients were 96.9 and 59.0%, respectively. Thirty-six percent of tumors were <or=1 cm(3) in volume. For these, sensitivity and specificity for tumor detection were 87% and 65% respectively. For evaluation of parametrial status, sensitivity was 80%, and specificity was 91.3%. A cut-off MRI tumor volume of 5.2 cm(3) predicted histologically confirmed lymph node metastases with a sensitivity of 78.6% and specificity of 72.5%.

CONCLUSION

Endovaginal magnetic resonance imaging has high sensitivity in the preoperative staging of uterine cervical cancer even for tumors <or=1 cm(3). It is an invaluable technique in planning fertility-conserving or radical surgical treatment of early stage cervical cancer.

Use of neoadjuvant chemotherapy prior to radical hysterectomy in cervical cancer: monitoring tumour shrinkage and molecular profile on magnetic resonance and assessment of 3-year outcome

The objective of this study is to assess tumour response to neoadjuvant chemotherapy prior to radical hysterectomy in cervical cancer using magnetic resonance (MR) to monitor tumour volume and changes in molecular profile and to compare the survival to that of a control group. Eligibility included Stage Ib-IIb previously untreated cervical tumours >10 cm(3). Neoadjuvant chemotherapy in 22 patients (methotrexate 300 mg x m(-2) (with folinic acid rescue), bleomycin 30 mg x m(-2), cisplatin 60 mg m(-2)) was repeated twice weekly for three courses and followed by radical hysterectomy. Post-operative radiotherapy was given in 14 cases. A total of 23 patients treated either with radical surgery or chemoradiotherapy over the same time period comprised the nonrandomised control group. MR scans before and after neoadjuvant chemotherapy and in the control group documented tumour volume on imaging and metabolites on in vivo spectroscopy. Changes were compared using a paired t-test. Survival was calculated using the Kaplan-Meier method. There were no significant differences between the neoadjuvant chemotherapy and control groups in age (mean, s.d. 43.3+/-10, 44.7+/-8.5 years, respectively, P=0.63) or tumour volume (medians, quartiles 35.8, 17.8, 57.7 cm(3) vs 23.0, 15.0, 37.0 cm(3), respectively, P=0.068). The reduction in tumour volume post-chemotherapy (median, quartiles 7.5, 3.0, 19.0 cm(3)) was significant (P=0.002). The reduction in -CH(2) triglyceride approached significance (P=0.05), but other metabolites were unchanged. The 3-year survival in the chemotherapy group (49.1%) was not significantly different from the control group (46%, P=0.94). There is a significant reduction in tumour volume and -CH(2) triglyceride levels after neoadjuvant chemotherapy, but there is no survival advantage.

Pretreatment tumour volume measurement on high-resolution magnetic resonance imaging as a predictor of survival in cervical cancer

OBJECTIVE

To evaluate pretreatment tumour volume as a predictor of survival in patients with cervical cancer using both endovaginal and external coil magnetic resonance imaging in order to achieve high spatial resolution and delineate small volume disease.

DESIGN

A retrosfection case series.

SETTING

A tertiary referral centre for gynaecological oncology.

POPULATION/SAMPLE

One hundred and six consecutive women with invasive carcinoma of the cervix underwent endovaginal and external coil magnetic resonance imaging on a 0.5-T or 1.5-T scanner.

METHODS

T2-W FSE images, sagittal and transverse to the cervix, were obtained and tumour volume was calculated on the sagittal images by the standard technique of multiplying the sum of the areas by the slice thickness. Patients were treated in accordance with normal clinical practice and their subsequent outcome was recorded. The relationships between clinical or imaging parameters and survival were assessed with Cox's proportional hazard method.

MAIN OUTCOME MEASURES

Disease-free survival.

RESULTS

In 89 of these women, the tumour was Stage I and 88 of the 106 were treated principally by surgery. The median tumour volume was 4.75 cm(3) (upper and lower quartiles 22 and 0.6). The median length of follow up of surviving patients was 223 weeks (quartiles 158 and 274 weeks). Stage, treatment type, lymphovascular space involvement, invasion of the parametrium, closeness of the excision margin, lymph node metastases, and magnetic resonance imaging measurements of tumour volume, parametrial invasion and lymph node disease were all significantly associated with survival in univariate analysis. Only magnetic resonance imaging measurement of tumour volume remained consistently and strongly associated with survival after multivariate analysis of parameters available prior to treatment (P= 0.001, Wald statistic 10.74). A receiver operating characteristic curve of tumour volume and disease-free survival confirmed the utility of this investigation and suggested that a cutoff around 13.0 cm(3) would predict survival with a positive predictive value of 0.93 and a negative predictive value of 0.75.

CONCLUSION

Magnetic resonance imaging assessment of tumour volume using both an endovaginal and an external coil approach provides an accurate prediction of prognosis in cervical cancer and defines a population of women at high risk of recurrence and death. The predictive value of this investigation is superior to the clinical and histological parameters previously used. Use of this technique permits a more accurate choice of treatment options. These results suggest that it is the size of tumour burden that determines the outcome rather than invasion beyond the anatomical margins of the uterus.

1H magnetic resonance spectroscopy of invasive cervical cancer: an in vivo study with ex vivo corroboration

The objective of this study was to establish in vivo (1)H-magnetic resonance (MR) spectroscopic appearances of cervical cancer using an endovaginal receiver coil and corroborate findings with magic angle spinning (MAS) MR spectroscopy of tissue samples. Fifty-three women (14 controls and 39 with cervical cancer) underwent endovaginal coil MR imaging at 1.5 T with T(1)- and T(2)-weighted scans sagittal and transverse to the cervix. Localized (1)H MR spectra (PRESS technique, TR 1600 ms, TE 135 ms) were accumulated in all controls and 29 cancer patients whose tumour filled > 50% of a single 3.4 cm(3) voxel. Peaks from triglyceride-CH(2) and -CH(3) were defined as present and in-phase (with the choline resonance), present but out-of-phase, or not present. Peak areas of choline-containing compounds were standardized to the area of unsuppressed tissue water resonance. Comparisons in observed resonances between groups were made using Fisher's exact test (qualitative data) and a t-test (quantitative data). Biopsies from these women analysed using MAS-MR spectroscopy and normalized to the intensity of an external standard of silicone rubber were similarly compared. Adequate water suppression permitted spectral analysis in 11 controls and 27 cancer patients. In-phase triglyceride-CH(2) resonances (1.3 ppm) were observed in 74% of tumours but in no control women (p < 0.001). No differences were observed in the presence of a 2 ppm resonance, choline-containing compounds or creatine in cancer compared with control women. However, ex vivo analysis showed significant differences not only in -CH(2), but also in -CH(3), a 2 ppm resonance, choline-containing compounds and creatine between tissues from control women and cancer tissue (p < 0.001, = 0.001, = 0.036, < 0.001 and = 0.004 respectively). On in vivo (1)H-MR spectroscopy, the presence of positive triglyceride-CH(2) resonances can be used to detect and confirm the presence of cervical cancer. However, technical improvements are required before routine clinical use.

1H magnetic resonance spectroscopy of preinvasive and invasive cervical cancer: In vivo-ex vivo profiles and effect of tumor load

PURPOSE

To compare in vivo (1)H magnetic resonance (MR) spectra of preinvasive and invasive cervical lesions with ex vivo magic angle spinning (MAS) spectra of intact biopsies from the same subjects and to establish the effects of tumor load in the tissue sampled on the findings.

MATERIALS AND METHODS

A total of 51 subjects (nine with normal cervix, 10 with cervical intraepithelial neoplasia [CIN], and 32 with cervical cancer) underwent endovaginal MR at 1.5 T. Single-voxel (3.4 cm(3)) (1)H MR spectra were acquired and voxel tumor load was calculated (tumor volume within voxel as a percentage of voxel volume). Resonances from triglycerides -CH(2) and -CH(3) and choline-containing compounds (Cho) were correlated with voxel tumor load. Biopsies analyzed by (1)H MAS-MR spectroscopy (MRS) had metabolite levels correlated with tumor load in the sample at histology.

RESULTS

In vivo studies detected Cho in normal, CIN, and cancer patients with no significant differences in levels (P = 0.93); levels were independent of voxel tumor load. Triglyceride -CH(2) and -CH(3) signals in-phase with Cho were present in 77% and 29%, respectively, of cancer subjects (but not in normal women or those with CIN), but did not correlate with voxel tumor load. Ex vivo cancer biopsies showed levels of triglycerides -CH(2) and -CH(3) and of Cho that were significantly greater than in normal or CIN biopsies (P < 0.05); levels were independent of the tumor load in the sample. The presence of -CH(2) in vivo predicted the presence of cancer with a sensitivity and specificity of 77.4% and 93.8% respectively, positive (PPV) and negative (NPV) predictive values were 96% and 68.2%; for -CH(2) ex vivo, sensitivity was 100%; specificity, 69%; PPV, 82%; and NPV, 100%.

CONCLUSION

Elevated lipid levels are detected by MRS in vivo and ex vivo in cervical cancer and are independent of tumor load in the volume of tissue sampled.

Esophageal cancer staging with endoscopic MR imaging: pilot study

The authors defined esophageal anatomy and evaluated esophageal cancer staging in a pilot group by comparing endoscopic magnetic resonance (MR) imaging results with pathologic and endoscopic ultrasonographic (US) results when available. A porcine esophagus, one volunteer, and 23 patients suspected of having esophageal cancer were imaged at 0.5 T. MR imaging was successful in 21 patients. Eight of these patients underwent esophagectomy (one after chemotherapy, which invalidated comparison with MR imaging; another did not undergo lymphadenectomy) and one underwent laparoscopy and nodal staging only; eight underwent US. When verified with pathologic staging, endoscopic MR imaging was accurate in six of seven patients (T stage) and five of six patients (N stage; nodal areas too obscured by artifact for comparison in one case). MR imaging and US results concurred in seven of eight (T stage) and five of eight (N stage) patients. No complications were observed. Endoscopic MR imaging is safe and probably comparable to endoscopic US, but with a tendency to overstage the disease.

The correlation of preoperative CT, MR imaging, and clinical staging (FIGO) with histopathology findings in primary cervical carcinoma

The aim of this study was to compare the preoperative findings of abdominal/pelvic CT and MRI with the preoperative clinical International Federation of Obstetrics and Gynecology (FIGO) staging and postoperative pathology report in patients with primary cancer of the cervix. Thirty-six patients with surgical-pathological proven primary cancer of the cervix were retrospectively studied for preoperative staging by clinical examination, CT, and MR imaging. Studied parameters for preoperative staging were the presence of tumor, tumor extension into the parametrial tissue, pelvic wall, adjacent organs, and lymph nodes. The CT was performed in 32 patients and MRI (T1- and T2-weighted images) in 29 patients. The CT and MR staging were based on the FIGO staging system. Results were compared with histological findings. The group is consisted of stage 0 (in situ):1, Ia:1, Ib:8, IIa:2, IIb:12, IIIa:4, IVa:6, and IVb:2 patients. The overall accuracy of staging for clinical examination, CT, and MRI was 47, 53, and 86%, respectively. The MRI incorrectly staged 2 patients and did not visualize only two tumors; one was an in situ (stage-0) and one stage-Ia (microscopic) disease. The MRI is more accurate than CT and they are both superior to clinical examination in evaluating the locoregional extension and preoperative staging of primary cancer of the cervix.

An inductively-coupled, detachable receiver coil system for use with magnetic resonance compatible endoscopes

PURPOSE

To construct an inductively-coupled receiver coil system for use with a magnetic resonance (MR) compatible endoscope, and to evaluate its use in a pilot group of patients with esophageal cancer.

MATERIALS AND METHODS

An inductively-coupled coil system, comprising a saddle geometry cylindrical receiver coil fitted as a sleeve around the endoscope tip and a pick-up coil housed within a channel of an MR-compatible endoscope, was designed and developed for use at 0.5 T. Twenty-three patients with esophageal cancer were recruited for MR endoscopy. In 17 cases, the endoscopic coil system was used in conjunction with an external surface coil in order to obtain information from the surrounding mediastinum. The examination took 40-50 minutes.

RESULTS

MR imaging using the inductively-coupled endoscopic coil was successful in 21 cases (one failed intubation and one artifact from unrelated external source). Image artifact was largely due to respiration and global patient motion in sedated individuals undergoing endoscopy.

CONCLUSION

Inductively-coupled coil systems may be used with endoscopes to allow improved safety through increased patient-system isolation and detachability of coils and electronics for repair or replacement with coils tuned for different frequencies.

Histopathologic correlation of high-resolution magnetic resonance imaging of human cervical tissue samples at 3 tesla: validation of a technique

RATIONALE AND OBJECTIVES

High-resolution magnetic resonance (HR-MR) images of human cervical tissue samples were correlated with low magnification histology to investigate the MR presentation of normal and pathologic anatomic structures in cervical tissue samples at 3T.

METHODS

Tissue samples were obtained from five large loop excision of the transformation zone (LLETZ) cone biopsies and one surgical specimen. HR-MR images (3D-Spin Echo sequence: TR/TE: 1500/60 milliseconds, voxel size of 117 x 208 x 234 microm) and low magnification (5x) histology sections were acquired in the same anatomical planes and correlated.

RESULTS

In vitro HR-MR imaging of cervical tissue samples correlated well with low magnification microscopic histology, demonstrating normal anatomy (epithelium and its mucus layer, connective tissue of the stroma, glands, blood vessels). In vitro HR-MR imaging adds information about tumor content and margins.

CONCLUSIONS

High resolution MR imaging of cervical tissue samples assists in the identification of both normal structures and pathologic changes.

Imaging of cancer of the cervix

Cancer of the endometrium is the most common invasive gynecologic malignancy in North America. Although transvaginal sonography is often the initial imaging examination in women with dysfunctional uterine bleeding, MRI offers multifactorial assessment once the diagnosis of endometrial cancer has been established. Specifically, preoperative contrast-enhanced MRI alters the likelihood ratios for myometrial invasion, which in turn affects type and extent of surgery performed. This information also helps identify patients who would most benefit from referral to a tertiary care center for treatment by a gynecologic oncologist.

Cervical carcinoma with full-thickness stromal invasion: relationship between tumor size on T2-weighted images and parametrial involvement

PURPOSE

The purpose of this work was to investigate the relationship between tumor size on T2-weighted images and parametrial involvement by cervical carcinoma with full-thickness stromal invasion and to evaluate whether the size of the tumor on T2-weighted images is a useful index of parametrial involvement.

METHOD

T2-weighted images of 33 patients with cervical carcinoma showed full-thickness stromal invasion. Three-dimensional diameters (transverse, anteroposterior, and craniocaudal) of the primary tumor were measured on T2-weighted images. The area and volume of the tumor were also calculated.

RESULTS

There were statistically significant differences between the patients with parametrial involvement and those without parametrial involvement for each tumor size. The criteria that showed the best accuracy for each tumor size were determined.

CONCLUSION

The tumor size on T2-weighted images is considered to be a useful index for evaluating parametrial involvement by cervical carcinoma with full-thickness stromal invasion.

Magnetic resonance imaging of the primary site in stage I cervical carcinoma: A comparison of endovaginal coil with external phased array coil techniques at 0.5T

OBJECTIVE

To compare endovaginal with pelvic phased array coil magnetic resonance imaging (MRI) in detection of Stage I cervical carcinoma by correlating the findings with histopathology.

PATIENTS AND METHODS

Forty consecutive patients with Stage I cervical carcinoma confirmed histologically were studied using an endovaginal coil alone immediately followed by a pelvic phased array coil. T1-W transverse and T2-W FSE sagittal images made with each coil were analyzed independently by two radiologists noting the presence and size of a mass within the cervix and any parametrial extension or involvement of adjacent organs. Tumor volumes were measured using the electronic calliper to compute tumor area on each slice and multiplying by the slice thickness. Thirty patients underwent radical hysterectomy, one a trachylectomy, one simple hysterectomy and four extended cone biopsies. Four patients had radiotherapy to the primary tumor. Following surgery, histopathologic findings were recorded and tumor volumes measured.

RESULTS

Tumor volumes ranged from 0-106 cm(3)(median 1.4 cm(3), mean 9 +/- 19.4 cm(3)). Thirty-six patients had correlation of the primary site with the surgical specimen. Agreement between observers was excellent for both endovaginal (k = 0.90) and pelvic phased array (k = 0.96) techniques. Combined sensitivity and specificity for both observers of endovaginal MR imaging for detection of tumor was 96% and 70%, respectively; for pelvic phased array imaging sensitivity was substantially less at 54%. Specificity was higher at 83.7%, probably because small abnormalities were seldom visible. In patients treated surgically, early parametrial involvement in four women on endovaginal MRI was confirmed histologically in two. Pelvic phased array imaging showed early parametrial involvement in four women and was confirmed in one.

CONCLUSION

Endovaginal MRI adds substantially to information from pelvic phased array images in the preoperative assessment of patients with early cervical cancer. J. Magn. Reson. Imaging 2000;12:1020-1026.

Design and use of internal receiver coils for magnetic resonance imaging

This review describes coils for MRI that are inserted into the body through natural orifices. It covers the design and implementation of small internal receiver coils for use in the pelvis and gastrointestinal tract. Normal anatomy delineated by the high resolution obtained by using these coils and the appearances in a number of disease states for each clinical application are described.

Value of magnetic resonance imaging with an endovaginal receiver coil in the pre-operative assessment of Stage I and IIa cervical neoplasia

OBJECTIVE

To assess the value of high resolution endovaginal magnetic resonance images (MRI) of the uterine cervix in planning management of early cervical cancer.

DESIGN

Prospective cross-sectional study.

SETTING

Specialist gynaecological oncology unit of a postgraduate teaching hospital.

PARTICIPANTS

Thirty nine women aged 25-76 years old (mean 42.5 years) with invasive carcinoma Stage I or IIa of the cervix.

METHODS

A ring coil was positioned endovaginally around the cervix. Imaging was performed on a 1.0 T HPQ Vista or 0.5 T Asset (Picker, Highland Heights, Ohio, USA) using T1 weighted and T2 weighted sequences in transverse and sagittal planes with thin slices (2.5 mm) and small fields of view (12 cm). Tumour volumes were measured and any extension into adjacent organs and parametrium was noted. The patients were followed up after treatment and the outcome related to the MRI findings.

RESULTS

There was one false positive and one false negative result among five Stage Ia patients being assessed for residual disease after cone biopsy or LLETZ. The MRI assessment of the size and distribution of the tumour was confirmed histologically in all 31 patients with Stage Ib or IIa disease who were treated surgically. One of these patients in whom no endocervical tumour was visible on MRI underwent radical trachelectomy. Three patients had radiotherapy as primary treatment. Patients with Stage Ib or IIa disease who had tumour volumes > 10 cm3 with early parametrial extension on MRI had a substantially worse prognosis at 24 months (disease-free survival 58.3% vs 95.5%, P = 0.003).

CONCLUSION

High resolution MRI with an endovaginal coil allows precise measurement of tumour volume and identifies patients with small volume disease who might be considered for more conservative therapy. This technique also reveals early parametrial invasion that cannot be identified reliably by any other method. Early parametrial invasion in women with large tumours appears to have a very much worse prognosis.

Cervical cancer

The stage estimated by clinical FIGO staging is the main determinant in guiding the treatment decisions. However, clinical FIGO staging does have inherent inaccuracies, because it does not include significant prognostic factors. Presently, MRI is not officially incorporated in the staging workup system; however, it is widely accepted as the most reliable imaging modality in evaluating cervical cancer and in treatment planning. MRI offers direct tumor visualization, accurate assessment of the depth of stromal invasion and tumor volume, lymph node evaluation, and reliable staging accuracy. Published reports show the superiority of MRI over clinical staging, and several recent works on dynamic MRI suggest further improvement of MRI in evaluating cervical cancer.