SIPAP: A new MR classification for pituitary adenomas

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Acta Radiologica ISSN: 0284-1851 (Print) 1600-0455

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Nepper-Rasmussen To cite this article: A. L. Edal, K.

Nepper-Rasmussen (1997) SIPAP: A new MR classification

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1 Acta Radiologica ISSN: (Print) (Online) Journal homepage: SIPAP: A new MR classification for pituitary adenomas A. L. Edal, K. Skjödt & H. J. Nepper-Rasmussen To cite this article: A. L. Edal, K. Skjödt & H. J. Nepper-Rasmussen (1997) SIPAP: A new MR classification for pituitary adenomas, Acta Radiologica, 38:1, To link to this article: Published online: 04 Jan Submit your article to this journal Article views: 2523 Full Terms & Conditions of access and use can be found at

2 Acta Radiologica 38 (1997) Printed in Denmark. All rights reserved Copyright 0 Acta Radiologica 1997 ACTA RADIOLOGICA ISSN SIPAP - A NEW MR CLASSIFICATION FOR PITUITARY ADENOMAS A. L. EDAL, K. SKJODT and H. J. NEPPER-RASMUSSEN Department of Radiology, Odense University Hospital, Odense, Denmark. Abstract Purpose: To present a new MR classification for pituitary adenomas, a grading system named SIPAP. Material and Methods: SIPAP is an acronym for the 5 juxtasellar directions of tumour extension to or penetration into adjacent structures of the sella region, using a 6- figure number for each adenoma. This retrospective study was based on 87 mid-field MR examinations of 56 patients with biochemically or surgically confirmed pituitary adenomas. Sagittal TI-weighted SE and coronal T1-weighted 3D FFE sequences before and after i.v. contrast administration were performed. Results: The SIPAP classification was well adapted to the material. All tumours except one postoperative remnant could be classified in the grading system. The classification was useful before and after treatment, for follow-up over a longer period, and for comparing adenomas with different hormonal activity with reference to patient age and sex. Conclusion: The SIPAP classification together with tumour size is an optimal meth- I od for the registration of pituitary adenomas. I Key words: Pituitary adenomas, classification; MR imaging. Correspondence: Anette Loft Edal, Radiology Department, Odense University Hospital, Sdr Boulevard 29, DK-5000 Odense C, Denmark. FAX: Accepted for publication I July MR imaging is regarded as the modality of choice in the diagnosis of pituitary adenomas (1, 4, 8, 9, 12, 13). In recent years there has been an increasing demand for a simple and useful MR classification based on the major directions of tumour growth. Our proposed MR classification for pituitary adenomas emanates from the KNOSP-STEINER classification (7) of parasellar growth, to which has been added a grading system for superior, inferior, anterior and posterior tumour extension. The object of this study was to construct an MR classification for the optimal radiological description of tumour delineation, tumour relationship to juxtasellar structures, and tumour size (height, length and width). This description should serve as a simple tool for registration that can be readily used by all staff. Material and Methods This retrospective study was based on 56 patients with pituitary adenomas (mean age 47.9 years, range years at the first examination). There were 35 women (mean age 44.2 years, range years) and 21 men (mean age 54.0 years, range years). A total of 87 MR examinations were performed in a period of 45 months. Thirty patients were examined once, 23 patients twice, 2 patients 3 times, and one patient 5 times. By means of a first MR examination 20 patients were evaluated preoperatively (Group A) (mean time before operation 38.1 days, range days). Twenty-three patients were evaluated postoperatively (Group B) (mean time after operation 53.7 months, range months); 3 of them had in addition had radiation therapy postoperatively at respectively 36, 24 and 18 months before MR imaging. Thirteen patients had pituitary adenomas diagnosed by MR but not proven by surgery (Group C). All patients were evaluated either by neurosurgical or endocrinological specialists before MR investigation. MR studies were performed on a 0.5 T superconducting system (Philips Gyroscan T5) with the use 30

NEW MR CLASSIFICATION FOR PITUITARY ADENOMAS SI PAP classification S I PRight pleff A P ~1 [TI jll ~1 r-01 0+4 0+2 0+4 0+4 0+1 0+1 Extension: Grading: Suprasellar 0 + 4 lnfrasellar 0 + 2 Parasellar 0

3 NEW MR CLASSIFICATION FOR PITUITARY ADENOMAS SI PAP classification S I PRight pleff A P ~1 [TI jll ~1 r Extension: Grading: Suprasellar lnfrasellar Parasellar Right Left Anterior 0 4 Posterior 0 4 Fig. 1. SIPAP classification based on the 6-figure registration. of a head coil (300 mm diameter). The acquisition matrix was 256x256 and the field of view 180 mm. A TI -weighted sagittal spin-echo sequence (TR/TE/acquisitions /15-20/2) with 5-mmthick slices and 0.5-mm gap was performed first. Then a coronal 3D fast field echo (3D-FFE) imaging protocol (TR/TE/acquisitions 30/13/2, flip angle 30" and slice thickness 2 mm without gap) was used in all examinations, with coronal images performed before and immediately after i.v. contrast enhancement of Gd-DTPA (469 mg/ml), using 0.1 rnmolkg b.w. Grading system The SIPAP classification is basically a 6-figure number describing the extrasellar extension of pituitary adenomas (Fig. 1). Reading the gradingnumber from left to right we obtain the 6 juxtasellar directions of interest: 1) suprasellar, 2) infrasellar, 3) parasellar (right side), 4) parasellar (left side), 5) anterior and 6) posterior. These identify the 2 sides of parasellar extension. Coronal MR images are chosen for grading the first 4 directions of tumour Grade 0 Grade 1 Grade 2 Grade 3 Grade 4 Monro block Fig. 2. The 5 grades of suprasellar tumour extension. a) Grade 0: No bulging of the adenoma into the suprasellar space. b) Grade 1 : The adenoma bulges upwards into the suprasellar cistern but without reaching the optical chiasm. c) Grade 2: It reaches the optical chiasm but without displacing it. d) Grade 3: The adenoma displaces and usually stretches the chiasm to a variable degree. e) Grade 4: Obstructive hydrocephalus of one or both lateral ventricles caused by tumour extension. 31

growth, while sagittal images are used for anterior and posterior extensions. 1. Suprasellar extension, Grades 0-4 (Fig. 2): Grade 0 (Fig.

4 A. L. EDAL ET AL. Grade 0 Grade 1 Grade 2 Fig. 3. The 3 grades of infrasellar tumour extension. a) Grade 0: Intact floor of sella. b) Grade 1: Focal bulging of the adenoma as an indirect sign of perforation of the dura and the floor of the sella. c) Grade 2: Tumour penetration beneath the sphenoid sinus. growth, while sagittal images are used for anterior and posterior extensions. 1. Suprasellar extension, Grades 0-4 (Fig. 2): Grade 0 (Fig. 2a): is characterized by the adenoma not bulging into the suprasellar space. The outline of the diaphragm of the sella is smooth. Grade I (Fig. 2b): In Grade 1, the adenoma bulges upwards into the suprasellar cistern without reaching the lower edge of the optical chiasm. Grade 2 (Fig. 2c): is characterized by the adenoma reaching the optical chiasm, without displacing or stretching it. Grade 3 (Fig. 2d): In Grade 3 the suprasellar bulging of the adenoma displaces and usually stretches the chiasm to a variable degree. The anterior part of the 3rd ventricle is obliterated more or less as the tumour deforms and elevates its anterior floor. The anterior horn of the lateral ventricles may be partially compressed, but there is no hydrocephalus caused by obstruction of the foramen of Monro. Grade 4 (Fig. 2e): In Grade 4, tumour extension is of such a degree that GSF flow is compromised through one or both foramens of Monro, resulting in hydrocephalus in one or both lateral ventricles. 2. Znfrasellar extension, Grades 0-2 (Fig. 3): Grade 0 (Fig. 3a): is characterized by an intact floor of sella. The inferior contour of the adenoma is smooth and rounded. The floor may be expanded because of tumour size, but there is no sign of penetration into the sphenoid sinus. Grade 1 (Fig. 3b): is characterized by focal bulging of the adenoma as an indirect sign of perforation of the dura and the floor of the sella. More or less tumour mass has penetrated irregularly into the sphenoid sinus, which may be almost completely filled by tumour. Grade 2 (Fig. 3c): is characterized by tumour penetration beneath the sphenoid sinus to the rhinopharynx and/or forward to the ethmoid area and nasal cavity. a b C Grade 0 Grade 1 Grade 2 Fig. 4. The KNOSP-STEINER classification of parasellar tumour extension (7). a) Grade 0; b) Grade 1; c) Grade 2; d) Grade 3; e) Grade 4. Grades 0-3 are distinguished from each other by a medial tangent - the intercarotid line - through the cross-sectional centres, and a lateral tangent on the intra- and supracavernous internal carotid arteries. Grade 4 corresponds to total encasement of the intracavernous carotid artery. d Grade 3 e Grade 4 32

NEW MR CLASSIFICATION FOR PITUITARY ADENOMAS Fig. 5. Anterior tumour extension: Grades 0 and 1 are distinguished from each other in the sagittal plane by a line perpendicular to the tubercle of sella.

Posterior tumour extension: Grades 0 and 1 are distinguished from each other in the sagittal plane. Grade 0: No posterior-inferior growth of the adenoma behind the clivus.

There may be complete destruction of the dorsum of the sella. 3 and 4. Parasellar extension, Grades 04 (Fig.

5 NEW MR CLASSIFICATION FOR PITUITARY ADENOMAS Fig. 5. Anterior tumour extension: Grades 0 and 1 are distinguished from each other in the sagittal plane by a line perpendicular to the tubercle of sella. Grade 0: No tumour extension into the anterior cranial fossa. Grade 1: The adenoma grows into the anterior fossa. Fig. 6. Posterior tumour extension: Grades 0 and 1 are distinguished from each other in the sagittal plane. Grade 0: No posterior-inferior growth of the adenoma behind the clivus. Grade 1: Tumour growth behind and inferior to the dorsum of the sella or clivus, through the diaphragm of sella and into the prepontine subarachnoid space. There may be complete destruction of the dorsum of the sella. 3 and 4. Parasellar extension, Grades 04 (Fig. 4): For grading the parasellar extension of pituitary adenomas we use the KNOSP-STEINER classification (7), where the grades 0, 1, 2, and 3 are distinguished from each other by a medial tangent - the intercarotid line - through the cross-sectional centres, and a lateral tangent on the intra- and supracavernous internal carotid arteries. Grade 0 represents the normal condition, and Grade 4 corresponds to the total encasement of the intracavernous carotid artery. KNOSP et al. (7) compared the MR grades with surgical findings and concluded that the critical area, where invasion of the cavernous sinus space becomes very likely, was located between the interca- rotid line and the lateral tangent, corresponding to Grade 2 above. 5. Anterior extension, Grades el (Fig. 5): are distinguished from each other in the sagittal plane by a line perpendicular to the tubercle of sella. Grade 0: In Grade 0 the adenoma may grow into the suprasellar cistern, but without tumour extension into the anterior cranial fossa. Grade I: is characterized by tumour extension into the anterior cranial fossa, defined as tumour growth anterior to the line perpendicular to the tubercle of sella. 6. Posterior extension, Grades 0-1 (Fig. 6): Grade 0: In Grade 0 the tumour extension may be suprasellar but without posterior-inferior growth of the adenoma behind the clivus. The extension is evaluated in the sagittal plane. Grade I: is characterized by tumour growth behind and inferior to the dorsum of the sella or clivus, through the diaphragm of sella into the subarachnoid space in front of the pons. There may be a complete destruction of the dorsum of the sella. Having used the SIPAP classification on a clinical material, as demonstrated in the examples in Fig. 7, we compared the results against patient sex and age, tumour size, and adenoma type as based on hormonal analysis. The collection of 6-figure numbers, each representing one adenoma, was divided into 2 groups. Group I, the low-grade group, comprised the grades 0-1, 0, 0-1,0-1, 0, and 0, and represented the nonpenetrating or less extended group of adenomas. Group 11, the high-grade group, comprised the grades 2-4, 1-2, 242-4, 1, and 1, and represented the tumours with a certain extrasellar extension. A high score in only one direction was enough to classify an adenoma in Group 11, as for instance the tumour registered as 0, 0, 0, 3, 0, 0 with a left parasellar extension of grade 3. We formed 3 groups according to patient age: under 25 years, years, and over 60 years. Concerning tumour size, we divided the adenomas into 3 groups according to the largest diameter: 10 mm or less, within mm, and 25 mrn or more. Results Pre-operative patient-group A (20 patients): There were 3 women and 3 men in Tumour Group I, 7 women and 7 men in Group 11. None of the patients were younger than 25 years of age. Four patients in Group I and 11 in Group I1 were between 25 and 60 years old, and 2 patients in Group I and 3 in Group I1 were more than 60 years old. 33

6 A. L. EDAL ET AL. Fig. 7. Examples of classification. A 49-year-old man with superior bilateral hemianopsia, most pronounced on the right side. He had been operated on 3 years earlier, non-radically, for a pituitary macroadenoma. Histological diagnosis was prolactinoma. Control MR, a) sagittal image and b) coronal image after i.v. contrast injection of Gd-DTPA, showed remnants of the macroadenoma with suprasellar tumour extension Grade 3, and no infrasellar growth Grade 0. Parasellarly the tumour extended into the right cavernous sinus space with encasement of the intracavernous carotid artery Grade 4, whereas there was no suspicion of tumour growth lateral to the medial tangent on the intraand supracavernous carotid arteries on the left side Grade 0. The tumour extended into the anterior cranial fossa Grade 1, but no posterior extension behind and inferior to the dorsum of sella Grade 0. Tumour size was measured as height 30 mm, length (a.p.) 36 mm, and width (right-left) 30 mm. Radiological registration: SIPAP classification 3, 0, 4, 0, 1, 0. Tumour size: 30~36x30 mm. In Group I, 4 tumours were 10 mm or less, and 2 between 10 and 25 mm. In Group 11, there were no tumours with a diameter of 10 mm or less, but 3 tumours within mm, and 11 with a diameter of 25 mm or more. Based on the post-operative histological analyses, Group I consisted of 5 HGH- and one ACTH-producing adenomas, and Group I1 of 7 0-cell, 3 HGH-, 2 PRL-, one HGHPRL- and one HGWTSH-producing adenomas. Post-operative patient-group B (23 patients): There were 3 women and 2 men in Group I, and 9 women and 8 men in Group 11. One man had diverse remnants of a PRL-producing adenoma outside the sella which could not be classified. None of the patients were below 25 years of age. Three patients in Group I and 14 in Group I1 were between 25 and 60 years old. Two patients in Group I and 3 in Group I1 were older than 60 years. Regarding tumour size, Group I had 4 patients with remnants of 10 mm or less, and one with a remnant between mm. In Group I1 there were 4 patients with remnants with diameters of 10 mm or less, 7 had remnants within mm, and in 6 patients the remnants were 25 mm or more. Histologically the primary tumours varied considerably. Group I consisted of 3 HGH-, one HGHPRL- and one ACTH-producing adenomas. Group I1 was divided into 8 0-cell, 2 HGH-, 4 PRL-, one HGWPRL-, one TSH- and one ACTHproducing adenomas. Non-operated patient-group C (1 3 patients): All patients were women, 7 in Group I and 6 in Group 11. They were generally younger than patient-groups A and B. Two patients in Group I and one in Group I1 were less than 25'years old, and 5 patients in Group I and 5 in Group I1 were between 25 and 60 years old. In Group I the largest diameters of 6 tumours were 10 mm or less, and one had a diameter of mm (14 mm), whereas in Group I1 one tumour was 10 mm, 3 between mm, and 2 were more than 25 mm in diameter. Clinically it was assumed that in Group I there were 3 adenomas of the chromophobe type and all the others in both groups were the PRL-producing type. Discussion The first widely used radiographic classification of pituitary adenomas was HARDY'S classification scheme, based on pneumoencephalography (2, 3). The grading of the suprasellar extension of adenomas was made possible by this indirect method. The classification was not well adapted to the CT modality as only one direction of tumour growth was taken into account. From a neurosurgical view it was also important to be aware of the other extrasel- 34

7 lar tumour extensions. WILSON (15) found that classification according to the degree of sellar destruction (grade) and extrasellar extension (stage) had a prognostic value and was helpful in designing therapy. He modified HARDY S grading system into an anatomical classification of pituitary adenomas in which he combined tumour size with its extension. This new classification was based on both radiographic and operative findings. However, classifying pituitary adenomas with reference to their size, whether they are micro- or macroadenomas, gives little information about tumour localisation. From a neuroradiological view the purpose is to give the clinicians a description of tumour extension that is as accurate as possible. With the introduction of MR, the resolution made it possible to achieve a high degree of diagnostic reliability (1). The anatomical details provided by MR imaging allow for a satisfactory topographical evaluation before the surgical approach is decided (6, 13). MR coronal slices combined with i.v. contrast medium enhancement demonstrate the lateral growth of pituitary adenomas with correlation to the adjacent parasellar structures (11) such as the internal carotid arteries, which are the most important structures to avoid during surgery (5, 9, 14). The KNOSP-STEINER classification made it much easier to demarcate parasellar tumour growth and it has become a useful grading system for predicting the involvement of the cavernous sinus (7). Our proposed SIPAP classification attempts to NEW MR CLASSIFICATION FOR PITUITARY ADENOMAS tary adenomas. It can be used to classify tumours combine the KNOSP-STEINER and HARDY-WILSON before treatment (usually operation), and it can be classifications. With this combination we were able used to follow tumour development over time, with to expand the classification of pituitary adenoma or without treatment. growth in lateral, upward and downward directions with the addition of forward and backward exten- REFERENCES sions. The advantage of this classification is that it 1. BALERIAUX D. & MATOS C.: MRI of pituitaq microadenooffers a precise description of tumour growth in all mas. Medica Mundi 36 (1991), 128. directions. 2. HARDY J.: Transsphenoidal surgery of hypersecreting pitui- The SIPAP classification was created without tary tumors. In: Diagnosis and treatment of pituitary tutaking into account the size of the tumour. Tumour mours, p Edited by P. 0. Kohler & G. T. Ross. Int. size can of course be easily added as a supplement Congr. Ser Elsevier, New York HARDY J. & VEZINA J. L.: Transsphenoidal neurosurgery of to the classification scheme for registration. LUN- DIN & PEDERSEN (10) performed a phantom study, recommending the measurement of 3 tumour diameters - width, length and height, and the formula 0.5~ width x length x height provided an adequate estimation of the tumour volume. The tumour diameter may well be a good supplement in evaluating the effect of pharmacological treatment as in the treatment of PRL-secreting adenomas, but we found it more important to classify the tumour according to local growth characteristics with the focus on adjacent structures. By dividing the tumours into 2 groups based on the SIPAP classifica- tion, as shown in this paper, we found that the tumour size correlated very well to the degree of extension. The proposed classification is based on coronal and sagittal TI-weighted MR images, which is a widely accepted way of scanning pituitary adenomas (5, 8, 9, 13). This procedure can easily be repeated with high accuracy, making it useful for follow-up and evaluation of tumour growth. The SIPAP classification can be used in untreated tumours as well as in postoperative or pharmacologically treated tumours. In our study only one postoperative tumour could not be classified because of growth of tumour remnants in more than one location. We consider that the SIPAP classification can give neurosurgeons a broad overview of tumour extension and can correlate the difficulties to be expected during surgery. It is important to know not only the degree of parasellar growth but also whether the tumour is growing anterior to the tubercle of sella or posterior behind the clivus because these areas are difficult to reach with the transphenoid approach. The suprasellar extension is important because of the compression of the optic chiasma and, in larger tumours, the compression of the ventricular system with possible CSF block through the foramen of Monro (8). Conclusion: The SIPAP classification is a useful grading system, that can be applied easily to pitui- intracranial neoplasm. In: Neoplasia in the central nervous system. Advances in neurology, vol. 15, p Edited by R. A. Thompson & J. R. Green. Raven Press, New York HIRSCH W. L. JR, ROPPOLO H., HAYMAN A. L. et al.: Sella and parasellar regions. Pathology. In: MR and CT imaging of the head, neck, and spine, p Edited by R. E. Latchaw. Mosby Year-Book, St. Louis HIRSCH W. L. JR, ROPWLO H., HAYMAN A. L. et al.: Sella and parasellar regions. Normal anatomy. In: MR and CT imaging of the head, neck, and spine, p Edited by R. E. Latchaw. Mosby Year-Book, St. Louis KAUFMAN B., KAUFMAN B. A,, ARAFAH B. U. et al.: Large pi- tuitary gland adenomas evaluated with magnetic resonance imaging. Neurosurgery 21 (1987),

8 A. L. EDAL ET AL. 7. KNOSP E., STEINER E., KITZ K. et al.: Pituitary adenomas with invasion of the cavernous sinus space. A magnetic resonance imaging classification compared with surgical findings. Neurosurgery 33 (1993), KUCHARCZYK W. & MONTANERA W. J.: The sella and parasellar region. In: Magnetic resonance imaging of the brain and spine, p Edited by S. W. Atlas. Raven Press, New York LUNDIN P., BERCSTROM K., THUOMAS K. A. et al.: Comparison of MR imaging and CT in pituitary macroadenomas. Acta Radiol. 32 (1991), LUNDIN P. & PEDERSEN F.: Volume of pituitary macroadenomas. Assessment by MRI. J. Comput. Assist. Tomogr. 16 (1992), NAKAMURA T., SCHORNER W., BITTNER. C. et al.: The value of paramagnetic contrast agent gadolinium-dtpa in the diagnosis of pituitary adenomas. Neuroradiology 30 (1988), SCHUBIGER 0.: Intrasellar tumours. Neuroradiological diagnosis. Riv. Neuroradiol. 4 (1991), Scorrr G., Yu C.-Y., DILLON W. P. et al.: MR imaging of cavernous sinus involvement by pituitary adenomas. AJNR 9 (1988), STEINER E., IMHOF H. & KNOSP E.: Gd-DTPA enhanced high resolution MR imaging of pituitary adenomas. Radiographics 9 (1989), WILSON C. B.: A decade of pituitary microsurgery. J. Neurosurg. 61 (1984),

TABLES. Imaging Modalities Evidence Tables Table 1 Computed Tomography (CT) Imaging. Conclusions. Author (Year) Classification Process/Evid ence Class

TABLES. Imaging Modalities Evidence Tables Table 1 Computed Tomography (CT) Imaging. Conclusions. Author (Year) Classification Process/Evid ence Class TABLES Imaging Modalities Evidence Tables Table 1 Computed Tomography (CT) Imaging Author Clark (1986) 9 Reformatted sagittal images in the differential diagnosis meningiomas and adenomas with suprasellar