Clinical Radiology 69 (2014) 549e550

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Correspondence

Re: Thoracic endometriosis syndrome: CT and MRI features

Sir d We read with great interest the paper by Rousset et al.1 dealing with the computed tomography (CT) and magnetic resonance imaging (MRI) features of thoracic endometriosis, published in Clinical Radiology in December 2013. We would like to thank the authors for the great quality of this work. We just wanted to add our own experience in diagnosing this rare, but probably overlooked, condition using MRI. Very few data on the MRI features of diaphragmatic endometriosis can be found in literature. We totally agree with the authors on the fact that this technique is far superior to CT in displaying diaphragmatic endometriosis lesions, thanks to its higher contrast resolution.1 Given the young

age of women affected by endometriosis, MRI should be the preferred technique where possible (Fig 1). Fat-saturated T1-weighted sequences are known to be very accurate for the detection of small endometriomas and should be routinely included in the standard MRI protocol for the exploration of the female pelvis, as pointed out by Siegelman et al.2 Whenever a pleural or diaphragmatic localization of endometriosis is clinically suspected, we routinely perform a three-dimensional (3D) gradient-echo fat-suppressed T1weighted sequence in the coronal plane for exploration of the thoracic bases. Fat-saturation is obtained using a dualecho Dixon technique with water reconstruction (LAVA sequence, GE Healthcare, Milwaukee, WI, USA). This technique is usually used in abdominal and pelvic imaging, especially for dynamic contrast-enhanced sequences. It enables homogeneous fat suppression compared with other techniques.3 This sequence may be acquired in a single breath-hold, with a section thickness of 4 mm, and usually lasts no more than 25e30 s, which is acceptable for the vast majority of these young patients. Therefore, motion artefacts, which can be responsible for false negatives at MRI, as

Figure 1 Example of diaphragmatic endometriosis in a 28-year-old patient who complained of intermittent pain in the right thoracic basal area. CT was performed 2 years earlier for suspected pulmonary embolism and was considered normal. (a) Retrospectively, well-delineated bulging of the diaphragmatic surface can be seen on the coronal-reformatted image (arrow). (b) This lesion is much more easily depicted on the coronal 3D dual-echo fat-suppressed T1 image (arrow). (c) Another small-sized endometrioma (arrow) viewed on coronal 3D dual-echo fat-suppressed T1weighted imaging. DOI of original article: http://dx.doi.org/10.1016/j.crad.2013.10.014.

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Correspondence / Clinical Radiology 69 (2014) 549e550

mentioned by Rousset et al.,1 can be reduced. Furthermore, concomitant exploration of the thoracic bases and pelvic cavity can be performed using the same body coil, which may prove useful given the known association between both localizations.4 In conclusion, we think that whenever diaphragmatic involvement is clinically suspected in patients with endometriosis, MRI is the most expedient imaging technique that may help diagnose haemorrhagic foci. In particular, the 3D dual-echo fat-suppressed T1-weighted sequence is a rapid sequence that can easily be added to the exploration of the pelvic cavity.

References 1. Rousset P, Rousset-Jablonski C, Alifano M, et al. Thoracic endometriosis syndrome: CT and MRI features. Clin Radiol 2014;69:323e30. 2. Siegelman ES, Oliver ER. MR imaging of endometriosis: ten imaging pearls. RadioGraphics 2012;32:1675e91. 3. Low RN, Panchal N, Vu AT, et al. Three-dimensional fast spoiled gradientecho dual echo (3D-FSPGR-DE) with water reconstruction: preliminary experience with a novel pulse sequence for gadolinium-enhanced abdominal MR imaging. J Magn Reson Imaging 2008;28:946e56. 4. Rousset-Jablonski C, Alifano M, Plu-Bureau G, et al. Catamenial pneumothorax and endometriosis-related pneumothorax: clinical features and risk factors. Hum Reprod 2011;26:2322e9.

P.F. Montoriol*, D. Da Ines, N. Bourdel, J.M. Garcier, M. Canis CHU Estaing, Clermont-Ferrand, France * Guarantor and correspondent: P.F. Montoriol, CHU Estaing, Clermont-Ferrand, France. E-mail address: [email protected] (P.F. Montoriol) Ó 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.crad.2014.01.023

Re: Thoracic endometriosis syndrome: CT and MRI features. A reply Sir d We would like to thank Dr Montoriol and coworkers for their interest1 in our paper2 and their comment on the usefulness of coronal breath-hold three-dimensional (3D) dual-echo fat-suppressed T1-weighted imaging. Diaphragmatic endometriosis is rare but also largely underdiagnosed. Adding this sequence to a standard pelvic magnetic resonance imaging (MRI) study, when clinically relevant, may improve thoracic endometriosis recognition.

DOIs of original article: http://dx.doi.org/10.1016/j.crad.2013.10.014, http://dx.doi.org/10.1016/j.crad.2014.01.023.

Diaphragmatic MRI is mainly contributory when positive, and we agree that hyperintense diaphragmatic foci on fat-suppressed T1-weighted sequence are highly suggestive of endometriotic implants. However, the main limitation of diaphragmatic MRI is its lack of sensitivity, especially for the detection of small implants. In our experience, 3D reformations in other orientation planes than that of the acquisition sequence show poorer spatial and contrast resolution. Thus, we recommend adding an axial transverse acquisition sequence to improve the detection because it is the most appropriate for evaluating the posterosuperior portion of the right diaphragm, where endometrial cell implantation most often occurs.3 Moreover, combining different acquisition planes can help ruling out false positives induced by susceptibility artefacts. Finally, although the breath-hold 3D dual-echo (or gradient-echo) fat-suppressed T1-weighted sequence seems to be a very suitable sequence for detecting diaphragmatic endometriosis, its accuracy has not been compared to that of fast spin-echo sequences, to the best of our knowledge. In conclusion, we totally agree with the comments of Dr Montoriol and coworkers, pointing out the relevance of a diaphragmatic screening in addition to routine pelvic MRI examination. However, diaphragmatic endometriosis exploration remains challenging and a complete dedicated MRI examination may also be considered in patients with high clinical suspicion of thoracic endometriosis.

References 1. Montoriol PF, Da Ines D, Bourdel N, et al. Re: Thoracic endometriosis syndrome: CT and MRI features. Clin Radiol 2014;69:549e50. 2. Rousset P, Rousset-Jablonski C, Alifano M, et al. Thoracic endometriosis syndrome: CT and MRI features. Clin Radiol 2014;69:323e30. 3. Alifano M, Trisolini R, Cancellieri A, et al. Thoracic endometriosis: current knowledge. Ann Thorac Surg 2006;81:761e9.

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P. Rousseta,*, M.-P. Revelb Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Universit e Claude Bernard Lyon 1, Lyon, France

Groupe Hospitalier Cochin Hotel-Dieu, Universit e Paris Descartes, Paris, France * Guarantor and correspondent: P. Rousset, Hospices Civils de Lyon, Department of Radiology, Centre Hospitalier Lyon Sud, 165 Chemin nite, France. du Grand Revoyet, 69495 Pierre Be Tel.: þ33 4 78 86 14 42; fax: þ33 4 78 86 65 18. E-mail address: [email protected] (P. Rousset) b

Ó 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.crad.2014.01.022

Re: Thoracic endometriosis syndrome: CT and MRI features.

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