Transrectal ultrasound for image-guided adaptive brachytherapy in cervix cancer – An alternative to MRI for target definition?

doi:10.1016/j.radonc.2016.01.021

Radiotherapy and Oncology

Volume 120, Issue 3, September 2016, Pages 467-472

https://doi.org/10.1016/j.radonc.2016.01.021 Get rights and content

Abstract

Purpose

To compare the maximum high risk clinical target volume (CTV_HR) dimensions and image quality between magnetic resonance imaging (MRI), transrectal ultrasound (TRUS) and computed tomography (CT) in image guided adaptive brachytherapy (IGABT) of locally advanced cervical cancer.

Material and methods

All patients with locally advanced cervical cancer treated with radiochemotherapy and IGABT between 09/2012-05/2013 were included in this study. T2-weighted MRI (1.5 tesla), TRUS and CT were performed before (MRI_preBT, TRUS_preBT) and/or after (MRI_BT, TRUS_BT and CT_BT) insertion of the applicator. 3D TRUS image acquisition was done with a customized US stepper device and software. The HR CTV was defined on 3D image sequences acquired with different imaging modalities by one blinded observer, in accordance to the GEC-ESTRO recommendations for MRI-based target volume delineation, as the complete cervical mass including the tumour, any suspicious areas of parametrial involvement and the normal cervical stroma. Maximum HR CTV width and thickness were measured on transversal planes. Image quality was classified using the following scoring system: Grade 0: not depicted, Grade 1: inability to discriminate, margin not recognizable, Grade 2: fair discrimination, margin indistinct, Grade 3: excellent discrimination, margin distinct. Descriptive statistics, mean differences between the groups, with MRI_BT as reference, and a paired t-test were calculated.

Results

Images from 19 patients (FIGO IB: 3, IIB: 9, IIIB: 5, IVB: 2) were available for analysis. The mean difference in maximum HR CTV width of TRUS_BT, TRUS_preBT, MRI_preBT, CT_BT to MRI_BT was 0.0 mm ± 4.7 (n.s.), −1.1 mm ± 5.6 (n.s.), 0.7 mm ± 6.4 (n.s.) and 13.8 mm ± 6.7 (p < 0.001). The mean difference in maximum HR CTV thickness of TRUS_BT, TRUS_preBT, MRI_preBT, CT_BT to MRI_BT was -3.4 mm ± 5.9 (p = 0.037), −3.4 mm ± 4.2 (p < 0.001), 2.0 mm ± 6.1 (n.s.) and 13.9 mm ± 6.3 (p < 0.001). Mean scores of image quality of the target volume was 2.9 for TRUS_preBT, 2.3 for TRUS_BT, 2.9 for MRI_preBT, 2.7 for MRI_BT and 2.1 for CT_BT.

Conclusion

For the assessment of the HR CTV in IGABT of cervical cancer, TRUS is within the intraobserver variability of MRI. TRUS is superior to CT as it yields systematically smaller deviations from MRI, with good to excellent image quality. Small differences of TRUS HR CTV thickness are likely related to differences in image slice orientation and compression of the cervix by the TRUS probe before insertion of the brachytherapy applicator.

Section snippets

Patients and treatment

All patients with cervix cancer FIGO Ib to IVb (paraaortic lymph node metastases) treated with definitive radiochemotherapy between September 2012 and May 2013 at the Department of Radiation Oncology of the Medical University of Vienna were included in this study. Treatment consisted of whole pelvis EBRT (45–50.4 Gy with 1.8 Gy per fraction) with or without concomitant chemotherapy and IGABT. IGABT was performed in the end or after EBRT in two applications with two fractions each delivering in

Patients

Twenty-three patients with locally advanced cervical cancer were treated with MRI based IGABT from September 2012 to May 2013 at the Department of Radiation Oncology of the Medical University of Vienna. Nineteen patients fulfilled the inclusion criterion. Four patients had to be excluded because of non-availability of the TRUS system during brachytherapy (n = 2) or because of TRUS related technical reasons (n = 2, only screenshots available, no 3D volume recorded).

In these 19 patients in total 30

Discussion

In this study we investigated the value of TRUS for HRCTV assessment in cervical cancer brachytherapy. For this purpose the HRCTV dimensions were measured and compared to MRI and CT. MRI_BT is currently considered the gold standard in IGABT and was therefore used as the reference measurement [15], [16], whereas CT and TRUS were the primarily investigated imaging modalities. MRI_preBT can be seen as an internal validation indicating the intraobserver variation – if TRUS is within the range of MRI

Conclusion

For the assessment of the HR CTV in IGABT of cervical cancer, TRUS is within the intraobserver variability of MRI. TRUS is superior to CT as it yields systematically smaller deviations from MRI, with good to excellent image quality. Small differences of TRUS HR CTV thickness is likely related to differences in image slice orientation and compression of the cervix by the TRUS probe before insertion of the brachytherapy applicator.

Conflict of interest notification

The Department of Radiotherapy at the Medical University of Vienna receives/received financial and/or equipment support for research and educational purposes from Nucletron an Elekta company., Varian Medical Systems, Inc., and Isodose Control B.V.

References (30)

R. Pötter et al.
Clinical impact of MRI assisted dose volume adaptation and dose escalation in brachytherapy of locally advanced cervix cancer
Radiother Oncol
(2007)
R. Pötter et al.
Clinical outcome of protocol based image (MRI) guided adaptive brachytherapy combined with 3D conformal radiotherapy with or without chemotherapy in patients with locally advanced cervical cancer
Radiother Oncol
(2011)
E.C. Rijkmans et al.
Improved survival of patients with cervical cancer treated with image-guided brachytherapy compared with conventional brachytherapy
Gynecol Oncol
(2014)
C.N. Nomden et al.
Clinical outcome and dosimetric parameters of chemo-radiation including MRI guided adaptive brachytherapy with tandem-ovoid applicators for cervical cancer patients: a single institution experience
Radiother Oncol
(2013 Apr)
C. Charra-Brunaud et al.
Impact of 3D image-based PDR brachytherapy on outcome of patients treated for cervix carcinoma in France: results of the French STIC prospective study
Radiother Oncol
(2012)
D. Minkoff et al.
Cervical cancer outcome prediction to high-dose rate brachytherapy using quantitative magnetic resonance imaging analysis of tumor response to external beam radiotherapy
Radiother Oncol
(2015 Apr)
A.N1. Viswanathan et al.
Three-dimensional imaging in gynecologic brachytherapy: a survey of the American Brachytherapy Society
Int J Radiat Oncol Biol Phys
(2010)
A.N. Viswanathan et al.
Computed tomography versus magnetic resonance imaging-based contouring in cervical cancer brachytherapy: results of a prospective trial and preliminary guidelines for standardized contours
Int J Radiat Oncol Biol Phys
(2007)
C. Ordeanu et al.
Local experience in cervical cancer imaging: comparison in tumour assessment between TRUS and MRI
Rep Pract Oncol Radiother
(2015)
J.A. Dimopoulos et al.
Recommendations from Gynaecological (GYN) GEC-ESTRO Working Group(IV): basic principles and parameters for MR imaging within the frame of image based adaptive cervix cancer brachytherapy
Radiother Oncol
(2012)

A.N. Viswanathan et al.

Comparison and consensus guidelines for delineation of clinical target volume for CT- and MR-based brachytherapy in locally advanced cervical cancer

Int J Radiat Oncol Biol Phys

(2014 Oct 1)

J.C.A. Dimopoulos et al.

Systematic evaluation of MRI findings in different stages of treatment of cervical cancer: potential of MRI on delineation of target, pathoanatomic structures, and organs at risk

Int J Rad Oncol Biol Phys

(2006)

C. Kirisits et al.

Dose and volume parameters for MRI-based treatment planning in intracavitary brachytherapy for cervical cancer

Int J Radiat Oncol Biol Phys

(2005)

C.A. Perez et al.

Tumor size, irradiation dose, and long-term outcome of carcinoma of uterine cervix

Int J Radiat Oncol Biol Phys

(1998 May 1)

J.C. Dimopoulos et al.

The Vienna applicator for combined intracavitary and interstitial brachytherapy of cervical cancer: clinical feasibility and preliminary results

Int J Radiat Oncol Biol Phys

(2006 Sep 1)

Cited by (50)

Clinical implementation of 3D transvaginal ultrasound for intraoperative guidance of needle implant in template interstitial gynecologic high-dose-rate brachytherapy
2023, Brachytherapy
To demonstrate novel clinical implementation of a 3D transvaginal ultrasound (3DTVUS) system for intraoperative needle insertion guidance in perineal template interstitial gynecologic high-dose-rate brachytherapy and assess its impact on implant quality.
Interstitial implants began with preimplant 3DTVUS to visualize the tumor and anatomy, with intermittent 3DTVUS to assess the implant and guide needle adjustment. Analysis includes visualization of the implant relative to anatomy, identification of cases where 3DTVUS is beneficial, dosimetry, and a survey distributed to 3DTVUS clinicians.
Seven patients treated between November 2021 and October 2022 were included in this study. Twenty needles were inserted under 3DTVUS guidance. The tumor and vaginal wall were well-differentiated in four and all seven patients, respectively. Patients with tumours below the superior aspect of the vagina are suited for 3DTVUS. Four radiation oncologists responded to the survey. There was general agreement that 3DTVUS improves implant and anatomy visualization and is preferred over standard 2D ultrasound guidance techniques.
Based on qualitative feedback from primary users and a small preliminary patient cohort, 3DTVUS imaging improves tumor and vaginal wall visualization during gynecologic perineal template interstitial needle implant and is a powerful tool for implant assessment in an intraoperative setting.
Contemporary image-guided cervical cancer brachytherapy: Consensus imaging recommendations from the Society of Abdominal Radiology and the American Brachytherapy Society
2022, Brachytherapy
Citation Excerpt :
In general, ultrasound-based dosimetry is two-dimensional and comparable to radiography. Uterine and cervical sizes measured relative to the tandem on US correlate well with MRI, with distances generally agreeing to within 3 mm in the sagittal plane (39–43), so point-based dosimetry is comparable to radiography. However, three-dimensional dosimetry methods using CT or MRI are preferred over ultrasound to minimize toxicities and improve tumor coverage.
To present recommendations for the use of imaging for evaluation and procedural guidance of brachytherapy for cervical cancer patients.
An expert panel comprised of members of the Society of Abdominal Radiology Uterine and Ovarian Cancer Disease Focused Panel and the American Brachytherapy Society jointly assessed the existing literature and provide data-driven guidance on imaging protocol development, interpretation, and reporting.
Image-guidance during applicator implantation reduces rates of uterine perforation by the tandem. Postimplant images may be acquired with radiography, computed tomography (CT), or magnetic resonance imaging (MRI), and CT or MRI are preferred due to a decrease in severe complications. Pre-brachytherapy T2-weighted MRI may be used as a reference for contouring the high-risk clinical target volume (HR-CTV) when CT is used for treatment planning. Reference CT and MRI protocols are provided for reference.
Image-guided brachytherapy in locally advanced cervical cancer is essential for optimal patient management. Various imaging modalities, including orthogonal radiographs, ultrasound, computed tomography, and magnetic resonance imaging, remain integral to the successful execution of image-guided brachytherapy.
Toward 3D-TRUS image-guided interstitial brachytherapy for cervical cancer
2022, Brachytherapy
Citation Excerpt :
In the second trial (5), images were acquired during an automated rotation of the TRUS probe along its longitudinal axis. MRI in the first series (4) was performed with a 1.5 Tesla system (Avanto, Siemens AG, Germany), MRI in the second series (5) was performed with a 0.35 Tesla system (Magnotom C, Siemens AG, Germany) according to the Gyn GEC ESTRO recommendations for imaging in IGABT (7). In both series (4,5), T2-weighted axial, and para-axial images were obtained covering the area from the tip of the uterine fundus to the caudal border of the pubic symphysis including any vaginal tumor extension with the applicator in place.
To qualitatively and quantitatively analyze needle visibility in combined intracavitary and interstitial cervical cancer brachytherapy on 3D transrectal ultrasound (TRUS) in comparison to gold standard MRI.
Image acquisition was done with a customized TRUS stepper unit and software (Medcom, Germany; Elekta, Sweden; ACMIT, Austria) followed by an MRI on the same day with the applicator in place. Qualitative assessment was done with following scoring system: 0 = no visibility 1 (= poor), 2 (= fair), 3 (= excellent) discrimination, quantitative assessment was done by measuring the distance between each needle and the tandem two centimeters (cm) above the ring and comparing to the respective measurement on MRI.
Twenty-nine implants and a total of 188 needles (132 straight, 35 oblique, 21 free-hand) were available. Overall, 79% were visible (87% straight, 51% oblique, 76% free-hand). Mean visibility score was 1.4 ± 0.5 for all visible needles. Distance of the visible needles to tandem was mean ± standard deviation (SD) 21.3 millimeters (mm) ± 6.5 mm on MRI and 21.0 mm ± 6.4 mm on TRUS, respectively. Difference between MRI and TRUS was max 14 mm, mean ± SD -0.3 mm ± 2.6 mm. 11% differed more than 3 mm.
Straight needles were better detectable than oblique needles (87% vs. 51%). Detectability was impaired by insufficient rotation of the TRUS probe, poor image quality or anatomic variation. As needles show a rather indistinct signal on TRUS, online detection with a standardized imaging protocol in combination with tracking should be investigated, aiming at the development of real time image guidance and online treatment planning.
Dosimetric impact of target definition in brachytherapy for cervical cancer – Computed tomography and trans rectal ultrasound versus magnetic resonance imaging
2022, Physics and Imaging in Radiation Oncology
Magnetic Resonance Imaging (MRI) based target definition in cervix brachytherapy is limited by its availability, logistics and financial implications, therefore, use of computed tomography (CT) and Trans Rectal UltraSonography (TRUS) has been explored. The current study evaluated the dosimetric impact of CT + TRUS based target volumes as compared to gold standard MRI.
Images of patients (n = 21) who underwent TRUS followed by MRI and CT, were delineated with High-Risk Clinical Target Volume in CT (CTV_HR-CT) and in MRI (CTV_HR-MR). CTV_HR-CT was drawn on CT images with TRUS assistance. For each patient, two treatment plans were made, on MRI and CT, followed by fusion and transfer of CTV_HR-MR to the CT images, referred as CTV_HR-MRonCT. The agreement between CTV_HR-MRonCT and CTV_HR-CT was evaluated for dosimetric parameters (D₉₀, D₉₈ and D₅₀; Dose received by 90%, 98% and 50% of the volumes) using Bland-Altman plots, linear regression, and Pearson correlation.
No statistically significant systematic difference was found between MRI and CT. Mean difference (±1.96 SD) of D₉₀, D₉₈ and D₅₀ between CTV_HR-MRonCT and CTV_HR-CT was 2.0, 1.2 and 5.6 Gy respectively. The number of patients who have met the dose constraints of D₉₀ > 85 Gy were 90% and 80% in MR and in CT respectively, others were in the borderline, with a minimum dose of 80 Gy. The mean ± SD dose-difference between MR and CT plans for bladder was significant (5 ± 13 Gy; p = 0.12) for D_0.1cm3, while others were statistically insignificant.
CT + TRUS based delineation of CTV_HR appear promising, provide useful information to optimally utilize for brachytherapy planning, however, MRI remains the gold standard.
Clinical values of transrectal ultrasound in judging GTV of cervical cancer
2021, Brachytherapy
To investigate the clinical value of transrectal ultrasound in judging the Gross Target Volume (GTV) of cervical cancer (CC).
A total of 196 CC patients admitted to the Department of Radiotherapy, China-Japan Union Hospital, Jilin University, from January 2016 to June 2019 were selected as the study subjects. The GTVs before and after applicator insertion were determined by transrectal ultrasound and compared with those judged by MRI.
All 196 patients were successfully undergoing applicator insertion according to the pretreatment plan. The GTV doses reached the clinical requirements during treatment. There was no significant difference between the GTVs judged by MRI and ultrasound before insertion in terms of upper/lower diameter (MRI Before 1 vs. Ultrasound Before 1) (MB1 vs. UB1), left/right diameter (MB2 vs. UB2), or ventral/dorsal diameter (MB3 vs. UB3), and the intragroup correlation coefficients (ICC) were 0.59, 0.77, and 0.66, respectively; moreover, there was no significant difference between the GTVs judged by MRI and ultrasound after insertion in terms of MRI After one vs. Ultrasound After one (MA1 vs. UA1), MA2 vs. UA2, and MA3 vs. UA3, and the ICC values were 0.62, 0.79, and 0.76, respectively.
Transrectal ultrasound can satisfactorily determine the GTV of CC and has certain value in brachytherapy for CC.
Ultrasound-guided Brachytherapy for Cervix Cancer
2021, Clinical Oncology
Radiotherapy and brachytherapy are the definitive treatments for locally advanced cervix cancer. The use of soft-tissue imaging, particularly magnetic resonance imaging, has enhanced their effectiveness and improved clinical outcomes. However, the use of magnetic resonance imaging is largely restricted to well-resourced centres in both the first and developing world and remains elusive to many less advantaged centres, particularly those in areas with a high burden of cervix cancer. Ultrasound is an accessible, affordable and accurate imaging modality that can be used throughout the brachytherapy procedure. Ultrasound is primarily used to ensure safe insertion of the applicator but can also be used to guide planning. The methods used to utilise ultrasound images for planning are described. Ultrasound is particularly useful as a verification aid to confirm applicator placement after patients are moved and transferred around the radiotherapy department. It can also be used to verify the dimensions of treatment volumes over the course of brachytherapy. There is a crucial unmet need for an accessible economical soft-tissue imaging modality in cervical brachytherapy. Ultrasound has the potential to meet this need.

View all citing articles on Scopus

View full text

Image guided brachytherapy in cervical cancerTransrectal ultrasound for image-guided adaptive brachytherapy in cervix cancer – An alternative to MRI for target definition?

Abstract

Purpose

Material and methods

Results

Conclusion

Section snippets

Patients and treatment

Patients

Discussion

Conclusion

Conflict of interest notification

Radiother Oncol

Radiother Oncol

Gynecol Oncol

Radiother Oncol

Radiother Oncol

Radiother Oncol

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Rep Pract Oncol Radiother

Radiother Oncol

Int J Radiat Oncol Biol Phys

Int J Rad Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Image guided brachytherapy in cervical cancer
Transrectal ultrasound for image-guided adaptive brachytherapy in cervix cancer – An alternative to MRI for target definition?