Standard high-resolution pelvic MRI vs. low-resolution pelvic MRI in the evaluation of deep infiltrating endometriosis
Arnaldo Scardapane, Filomenamila Lorusso, Marco Scioscia, Annunziata Ferrante, Amato Antonio Stabile Ianora & Giuseppe Angelelli European Radiology ISSN 0938-7994 Volume 24 Number 10 Eur Radiol (2014) 24:2590-2596 DOI 10.1007/s00330-014-3297-4
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Author's personal copy Eur Radiol (2014) 24:2590–2596 DOI 10.1007/s00330-014-3297-4
UROGENITAL
Standard high-resolution pelvic MRI vs. low-resolution pelvic MRI in the evaluation of deep infiltrating endometriosis Arnaldo Scardapane & Filomenamila Lorusso & Marco Scioscia & Annunziata Ferrante & Amato Antonio Stabile Ianora & Giuseppe Angelelli
Received: 26 March 2014 / Revised: 26 May 2014 / Accepted: 26 June 2014 / Published online: 10 July 2014 # European Society of Radiology 2014
Abstract Objective To compare the capabilities of standard pelvic MRI with low-resolution pelvic MRI using fast breath-hold sequences to evaluate deep infiltrating endometriosis (DIE). Methods Sixty-eight consecutive women with suspected DIE were studied with pelvic MRI. A double-acquisition protocol was carried out in each case. High-resolution (HR)-MRI consisted of axial, sagittal, and coronal TSE T2W images, axial TSE T1W, and axial THRIVE. Low-resolution (LR)MRI was acquired using fast single shot (SSH) T2 and T1 images. Two radiologists with 10 and 2 years of experience reviewed HR and LR images in two separate sessions. The presence of endometriotic lesions of the uterosacral ligament (USL), rectovaginal septum (RVS), pouch of Douglas (POD), and rectal wall was noted. The accuracies of LR-MRI and HRMRI were compared with the laparoscopic and histopathological findings. Results Average acquisition times were 24 minutes for HRMRI and 7 minutes for LR-MRI. The more experienced radiologist achieved higher accuracy with both HR-MRI and LR-MRI. The values of sensitivity, specificity, PPV, NPV, and accuracy did not significantly change between HR and LR images or interobserver agreement for all of the considered anatomic sites. Conclusions LR-MRI performs as well as HR-MRI and is a valuable tool for the detection of deep endometriosis extension. A. Scardapane (*) : F. Lorusso : A. Ferrante : A. A. Stabile Ianora : G. Angelelli Interdisciplinary Department of Medicine, University Hospital “Policlinico” of Bari, Piazza Giulio Cesare, 11, 70124 Bari, Italy e-mail:
[email protected] M. Scioscia Department of Obstetrics and Gynecology, Sacro Cuore Don Calabria General Hospital, Negrar, Verona, Italy
Key Points • High- and low-resolution MRI perform similarly in deep endometriosis evaluation • Low-resolution MRI significantly reduces the duration of the examination • Radiologist experience is fundamental for evaluating deep pelvic endometriosis Keywords Diagnosis . Magnetic resonance imaging . Pelvis . Female urogenital disease . Endometriosis
Introduction Deep infiltrating endometriosis (DIE) is defined as endometriotic lesions penetrating into the retroperitoneal space or the wall of pelvic organs to a depth of at least 5 mm, resulting in fibrosis and muscular hyperplasia [1]. Deep endometriosis involves, in descending order of frequency, the uterosacral ligaments (USL), the rectosigmoid colon, the vagina, and the bladder [2]. Diagnosis of DIE is challenging because physical examination has poor accuracy in detecting the different locations affected by DIE, since most of the lesions are inaccessible to digital pelvic examination [3]. Although a definitive diagnosis of endometriosis is obtained by laparoscopic visualisation of suspicious lesions, a preoperative imaging evaluation of the location and extent of disease is crucial to ensure the best therapeutic procedure and treatment planning, especially in cases of bowel involvement. To date, several imaging techniques have been proposed to diagnose DIE, including transvaginal and transrectal ultrasound, double-contrast barium enema, computed tomography (CT), and magnetic resonance imaging (MRI), and each has both advantages and limitations for pre-surgical assessment of the patient. Nowadays, many studies have shown that MRI remains the
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best non-invasive method to evaluate the different locations of DIE, with an overall sensitivity of 90 % [4–6]. Given its large field of view based on multiplanar capabilities and outstanding contrast resolution, MR imaging allows an accurate diagnosis of both anterior and posterior compartments of the pelvis [4, 7–9]. Extensive pelvic adhesions and ureteral involvement are also appreciated, representing important indications for MR imaging [4]. Moreover, the association of MRI and contrast-enhanced MR colonography has been shown to be a feasible and promising technique for a complete evaluation of deep pelvic endometriosis, since the retrograde colon distension and intravenous administration of gadolinium-based contrast medium may improve the accuracy of MRI for detection of colorectal implants, even for less experienced radiologists [4, 6, 10, 11]. Despite these advantages, MRI is often a poorly tolerated examination, particularly due to the duration of the procedure and the anxiety and claustrophobia experienced by patients. Based on these findings, the aim of the present study was to evaluate the accuracy of a fast low-resolution MRI imaging protocol using single-shot (SSH) T2 and fast breath-hold T1 images to predict the location of deep infiltrating endometriosis, using laparoscopic and histological data as the reference standard.
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MR findings were always transmitted to the referring gynaecologist before laparoscopy, which was scheduled for all of the patients within two to nine weeks (median 50 days). At surgery, the presence, site, number, size, and extent of endometriotic lesions were carefully noted, and all surgical specimens were assessed histologically to confirm the presence of endometriosis. MR findings were compared with those from laparoscopy, which is considered the gold standard.
MRI protocol and image analysis Magnetic resonance images were acquired with a 1.5 T MR imaging device (Philips, Achieva 1.5 T) with a four-channel phased-array coil (SENSE-body coil). Pelvic MRIs were performed regardless of menstrual cycle phase. Patients were asked to refrain from voiding for 30 minutes before the procedure, and an antiperistaltic drug (10 mg butylscopolamine (Buscopan), Boehringer Ingelheim, Germany) was injected intramuscularly just before imaging. No bowel cleansing was performed. All of the women were studied with a double-imaging protocol after having obtained written informed consent. Firstly, a standard high-resolution HR pelvic protocol (HRMRI) was carried out as follows:
Materials and methods & Study population Our prospective single-centre study was authorized by the local ethics committee and carried out between December 2012 and December 2013. Sixty-eight consecutive patients (mean age, 33.6±5.5 years) with clinical suspicion of DIE were enrolled. All patients had previously undergone gynaecological assessment for endometriosis, infertility, or chronic pelvic pain. Inclusion criteria were as follows: 1) clinical symptoms suggestive of endometriosis, including chronic pelvic pain, dysmenorrhea, dyspareunia, and infertility (n=24); 2) sonographic evidence of endometriotic ovarian cysts or peritoneal implants (n=31); 3) detection on gynaecological examination of endometriotic nodules at the posterior vaginal fornix, rectum, or uterosacral ligaments (n=18); 4) symptoms suggestive of bladder or colorectal endometriosis, such as tenesmus and dysuria (n = 9), abdominal pain before and during defecation, rectal pain during menstruation, irritable bowel syndrome, and rectal tenesmus (n= 28), respectively. None of the patients had a history of major abdominal surgery. Nine patients had previous appendectomy while 16 had already undergone surgery for enucleation of endometrioma.
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T2-weighted turbo spin-echo (TSE) in the axial, coronal, and sagittal planes (matrix 512×512; field of view (FOV) 260 mm; number of signal averages (NSA) 3; TE 110 ms; shortest TR; number of sections 24; thickness 4–5 mm; acquisition time 3 minutes 30 seconds); T1-weighted TSE sequences in the axial plane (matrix 512×512; FOV 260 mm; NSA 2; TE 11 ms; shortest TR; number of sections 24; thickness 5 mm; acquisition time 3 minutes 5 seconds); T1-weighted high-resolution isotropic volume with fat suppression (THRIVE) sequences in the axial plane (matrix 256×256; number of sections 100; thickness 2 mm; SENSE factor 4; shortest TE/TR; flip angle 10°; FOV 350 mm, acquisition time 30 seconds).
Subsequently, the following fast low-resolution pelvic protocol (LR-MRI), using breath-hold T2- and T1-weighted images, was acquired: &
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Axial, coronal, and sagittal single-shot fast spin echo (SS FSE) T2-weighted (T2W) sequences in the axial plane (thickness 4–5 mm; TE 100 ms; shortest TR; flip angle 90°; matrix 320×320; FOV 350–380 mm; breath-hold acquisition) T1-weighted (T1W) axial sequences (thickness 5 mm; TE 4.6 ms in phase; shortest time to repeat (TR); matrix 256×
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256 with 512×512 reconstruction matrix; (FOV) 350– 380 mm; breath-hold acquisition); Two radiologists (A.S. with 10 years of experience and F.L. with 2 years of experience, identified throughout the manuscript as R1 and R2, respectively) independently reviewed the examinations. Both radiologists were aware of the clinical suspicion of deep endometriosis but were not directly involved in the image acquisition session. Two separate sessions were established for image interpretation before laparoscopy: in the first session, the radiologists were asked to review the LR-MRIs, and in the second session, which was scheduled 10 days later, the HR-MRIs were interpreted. THRIVE sequence was considered as a part of both protocols and was included in both interpretation sessions. Both image quality and diagnostic confidence were assessed for both series of images using a four-point scale, as follows: 1) not adequate for diagnosis, 2) poor, 3) sufficient, and 4) good. The diagnosis of DIE was established according to the criteria suggested by Bazot et al. [4], based on the presence of morphological abnormalities (low-signal-intensity nodules or spiculated masses on T2-weighted sequences) associated with high-signal-intensity foci corresponding to endometrial glands and small haemorrhagic foci on T2- and T1-weighted and/or fat-suppressed sequences. The reviewers were asked to report lesions of uterosacral ligaments (USL), rectovaginal septum (RVS), rectum, and pouch of Douglas (POD) obliteration. To identify intestinal lesions, we took into account the specific signs classified by Kataoka et al. [7] as direct signs (presence of parietal nodules or plaques with low signal intensity on T2-weighted sequences and high-signalintensity foci on T1-weighted sequences) and indirect signs (adhesions between bowel loops, uterus, and/or adjacent organs, abnormal angulation of bowel loops, and retroverted uterus). Tethering of pelvic structures and loss of the corresponding cleavage planes, without appreciable nodular lesions, suggested a diagnosis of pelvic-space obliteration caused by adhesions. In addition, bladder and ureteral lesions were reported.
Statistical analysis Image quality and diagnostic confidence between HR-MRI and LR-MRI were compared using the Wilcoxon rank test. Sensitivity, specificity, negative (NPV) and positive (PPV) predictive values, and diagnostic accuracy of both radiologists were calculated for each site examined, with laparoscopy considered as the gold standard for diagnosis. The differences in sensitivities and specificities were analysed using the McNemar test as described by Hawass in 1997 [12].
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Interobserver agreement was calculated with the Cohen’s kappa test. Statistical significance was set at p
