The sellar/juxtasellar region comprises the sella turcica, pituitary gland, cavernous sinus, and suprasellar cistern^1. It is an anatomically complex area that represents a crucial crossroad of important adjacent structures including pituitary region, contents of cavernous sinus, contents of suprasellar cistern, hypothalamus through the pituitary stalk and dural reflections forming the diaphragm sellae and the walls of the cavernous sinuses². Although the cavernous sinus represents the most relevant juxtasellar structure, from the practical and clinical point of view all the structures that surround the sella turcica can be included. The anatomy of the sellar and juxtasellar region is intricate, and the pathology diverse. Various types of tumors, cysts, vascular lesions, inflammatory processes, infections and congenital lesions are found in and around the sella.

The clinical presentation of the sellar and juxtasellar lesions is also very variable. Pituitary axis dysfunction, visual field defects, hydrocephalus, intracranial mass effect and other neurologic deficits are some of the most common features.

Many different imaging ^(2,3,4,5,6) modalities have been used for assessment of this area, but for the most part the introduction and widespread use of high-resolution computed tomography (CT) relegated its imaging predecessors, such as plain skull roentgenograms, pleuridirectional tomography and pneumoencephalography to obsolescence. Magnetic resonance imaging (MRI) is now widely available, and considerable body of experience has been accumulated in using it to evaluate this region. MRI is now accepted as the imaging procedure of choice in the evaluation of sellar and juxtasellar pathology5. Its major advantages are its superior soft tissue contrast and its capacity for multiplanar imaging. Also, there is no artefact from bone, and the patient is not exposed to ionizing radiation. Use of I.V. gadolinium is very helpful in defining sellar and juxtasellar pathologies. The advent of dynamic contrast study has proved very useful in detection of pituitary microadenoma. Involvement of the optic chiasm, cavernous sinus, sphenoid sinus, orbit, temporal lobes and carotid arteries can all be best seen with MRI. CT is preferred for evaluating calcification and bone detail. The CT has its own drawbacks of high doses of ionizing radiation, artifacts due to presence of bony structures and inherent limitation of soft tissue resolution. But CT still remains important screening modality. Regardless of which imaging modality is used, it is useful to review the normal radiological anatomy and to survey the more common types of pathologic entities that occur in it.

It is important to make an attempt to characterize the histological etiology of masses involving sellar, juxtasellar region. This is of profound clinical importance as this determines the use of surgical versus nonsurgical techniques, a transsphenoidal versus intracranial surgical approach and the degree of resection.

In present study, we have evaluated 100 patients, having referred with strong clinical, hormonally suspicion showing abnormality in the sellar, paraasellar region.

AIMS AND OBJECTIVES

Aim of the study was to detect and characterize sellar and juxtasellar lesions by MRI and to study the role of various techniques of MRI in diagnosis of sellar and juxtasellar lesions and evaluation of MRI in management sellar and juxtasellar lesions.

This is a retrospective study of MRI of 100 patients during the period of August 2020 to December 2022. MR imaging was performed on a 1.5 TESLA 16 channel MRI machine in our department of Radiodiagnosis. A standard head coil was used for the examination. Informed written consent was taken in all patients.

Study included 100 patients both from inpatient and outpatient department having sellar and juxtasellar lesion on MRI. Patient referred for MRI having sellar and juxtasellar lesion are included in study/Patient in whom sellar and juxtasellar region was secondarily affected by direct extension from neighboring structures are included/Postoperative follow-up MRI studies are included in study. Patient with acquired empty sella turcica/ with congenital anomalies like septo-optic dysplasia, hypoplastic pituitary gland, pituitary stalk interruption syndrome are excluded from study.Patients with metabolic diseases having abnormal sella are/ haveing clinical or hormonological suspicious for microadenoma with normal MRI  excluded from study.The patients having contraindications to MRI were also excluded.

MRI Protocol:

Precontrast: First the brain screening sequence was performed with T1W, T2W and FLAIR axial sequences. After this, high resolution T1SE and T2SE sequences focused on the sellar region are performed in all cases, using following parameters.

Table 1: MRI Protocol

Post-contrast study was done in all patients. All cases with sellar and juxtasellar lesions underwent T1FS postcontrast axial, coronal and sagittal sequence in all cases using Gadolinium DTPA. The dose of Gadolinium DTPA (0.1mmol/kg body weight) was preloaded in a 10 ml syringe and was injected intravenously with a 22-gauge blue intravenous catheter placed in the antecubital fossa. Saline flushing with 5 ml was performed after injection of intravenous Gadolinium DTPA.

The gradient sequence was used for evaluation of foci of hemorrhage and calcification in all cases. Contrast enhanced MR angiography using 3D contrast angiography sequence was obtained.

The DWI and ADC sequence was done in all cases used for evaluation of consistency of lesion. B value 0 and 1000 were used.T2 3D DRIVE and SPIR image obtained in one patient having optic pathway glioma.

Dynamic postcontrast study: In 8 cases of suspected pituitary microadenoma on clinical/hormonal evaluation, rapid dynamic postcontrast images were obtained. Scanning commenced with T1 TSE weighted images obtained in the coronal plane using thin three mm sections. The FOV was maintained at 16 cm. Twenty-four dynamic sequential images in six fixed sections in the coronal plane over a period of 240 seconds were obtained during slow intravenous injection of IV Gadolinium DTPA.

For objective evaluation the enhancement pattern of a microadenoma and adjacent normal pituitary gland parenchyma was compared.MR Spectroscopy was done in 2 cases to differentiate etiology of sellar and juxtasellar lesion in addition to cMRI and DWI.

Table 2: Determination of the type of pathological MRS^7,8

We had 50 patients of pituitary macroadenoma. KNOSP classification was used for grading cavernous sinus invasion in them. ^9,10,11

Three lines are drawn between the supraclinoid internal carotid artery and intracavernous internal carotid artery on coronal MR images 1,2. 1. medial tangent, 2 intercarotid line and 3. lateral tangent. These lines are used to define 4 grades of tumor invasion:

Grade 0: tumor remains medial to the medial tangent

Grade 1: tumor extends to between the medial tangent and the intercarotid line

 Grade 2: tumor extends to between the intercarotid line and the lateral tangent

Grade 3: tumor extends lateral to the lateral tangent

3A: above the intracavernous internal carotid artery into the superior cavernous sinus compartment

3B: below the intracavernous internal carotid artery into the inferior cavernous sinus compartment

Grade 4: complete encasement of intracavernous internal carotid artery Following is our interpretation:

Grade 0 and 1: no invasion Grade 2: possible invasion Grade 3: probable invasion Grade 4: definite invasion

FIGURE 1 : Knosp classification

Pituitary macroadenomas were most commonly found pathologies in sellar and juxtasellar region. Craniopharyngioma, Pituitary microadenomas, Meningioma, Epidermoid cyst were less commonly found in this region. Chordoma, Germinoma, Pilomyxoid astrocytoma, Tuberculoma, Cavernous sinus thrombosis in case of rhino cerebral Mucor mycosis were least common pathologies found in sellar and juxtasellar region. (Table 3)  Majority of cases of macroadenomas show Knosp I or Knosp II grading. (Table 5) Majority of Macroadenomas and meningioma show solid morphology. Epidermoid cyst shows cystic variety. Most of Craniopharyngioma showed mixed morphology.(Table 6) Majority of macroadenomas shows haemorrhage and bony erosion. Calcification, hydrocephalus and Peritumoral oedema were less commonly found in macroadenomas. Majority of Craniopharyngioma shows calcification and hydrocephalus. Hydrocephalus, Peritumoral oedema and dural tail sign commonly found in meningioma.(table 4) MRI and histopathological correlation was done. Out of 84 cases, 81 cases show well-corelated Imaging diagnosis with Pathological diagnosis. (Table 7)

Table 3: Distribution of pathologies in sellar and juxtasellar region.

4 :Knosp’ grading in cases of macroadenomas.

                                                         Table 5 :Morphology of lesions

Table 6:Associated features

TABLE 7: MRI and histopathological correlation

Regarding birth hypoxia, 5 neonates (2.2%) in the bilateral pass group were affected, compared to 4 (28.6%) in the bilateral refer group. In the high-risk category, 87 neonates (37.7%) in the bilateral pass group were classified as high risk, compared to 12 (85.7%) in the bilateral refer group, including 3 (75.0%) in the left refer and right pass group, and none in the right refer and left pass group. (Table 1)

Table 1: Demographic and Clinical Characteristics of Neonates Based on Screening Outcomes (n=250)

231 (92.4%) of the participants had OAE (1 Week): B/L Pass. 14 (5.6%) of the participants had OAE (1 Week): B/L Refer. 4 (1.6%) of the participants had OAE (1 Week): L -Refer, R -Pass. 1 (0.4%) of the participants had OAE (1 Week): R-Refer, L-Pass.

7 (70.0%) of the participants had OAE (3 Months): B/L Pass. 3 (30.0%) of the participants had OAE (3 Months): B/L Refer.

4 (80.0%) of the participants had OAE (6 Months): B/L Pass. 1 (20.0%) of the participants had OAE (6 Months): B/L Refer

Table 2: Results of OAE

The one participant who had bilateral ‘refer’ OAE at 6 months underwent a detailed Auditory Workup

The present study was undertaken with the aim of evaluating MRI findings in sellar, juxtasellar lesions and in assessing diagnostic accuracy of MRI in characterization of and histological typing of sellar juxtasellar lesions. This was done by correlating MRI findings with clinical features, surgical findings and histopathological diagnosis. 100 patients who were having strong clinical complaints suggestive of sellar and juxtasellar lesions and showing hormonal abnormality were evaluated.

Ophthalmological complaints followed by symptoms of the raised intracranial tensions were the most common clinical presentations in our series. This is explained by the fact that, most patients having lesions show suprasellar extension. So, the ophthalmological complaints were due to displacement and compression of the optic chiasm. This is also noted by Johnsen et¹¹.

The most common lesion detected in our study was pituitary adenoma (58 out of 100). It matches Benjamin et al¹² and Johnsen et al¹¹ publications.

The coronal T1W image is useful for delineation of sphenoid sinus anatomical variation and posterior ethmoidal sinus variation and relation with optic nerve is useful for surgical transsphenoidal approach of pituitary lesion.^2-3

We found narrowing of vessels in 15 patients and complete block in 3 patients with the help of contrast MR angiography. The MR angiography is useful to evaluate proper relation of cavernous part of ICA with sellar and juxtasellar lesion. This information is also useful to reduce the risk of intraoperative vascular injury.^13,14,15. Postcontrast 3 D TOF MR angiography is better than noncontrast one as it reduces overestimation of narrowing.¹⁶

 We had one patient having juxtaasellar extension of juvenile nasopharyngeal angiofibroma. The MR angiography is important in this condition to identify feeder artery and preoperative chemoembolization of feeding vessels to reduce intraoperative bleeding.¹⁷

MR spectroscopy is useful for chemical composition of lesion^18,19. High cho/cr ratio in lesion s/o high malignant potential. One patient we found high cho/cr ratio (5.2). It helped to diagnose pilomyxoid astrocytoma (WHO grade 2)²⁰ and exclude hypothalamic optochiasmatic glioma which would be WHO grade 1. In 1.5 T MRI, it is difficult to have voxel less than 1 cc. So, in sellar and juxtasellar region, MR spectroscopy is of limited use. We had spectroscopy done in only 2 patients. In selected patients in whom, MR spectroscopy is needed, 3 T MR is preferable.

In the present study, there were 58 pituitary adenomas which constituted about 58 % of total pathologies in sellar and juxtasellar regions. Out of 58 adenomas 50 were macroadenomas and 8 were microadenomas by size criterion. proportion was about 6.6:1. Johnsen et al¹¹ found the total proportion of macro to microadenomas 2.5:1. Patients with macroadenomas typically presented with symptoms of mass effect rather than endocrinological disturbances. In our study about 68% patients presented with symptoms of diminution of vision. The height of macroadenomas producing visual disturbances was found to be more than 15 mm. This explained the larger no. of patients presenting with visual disturbances. Johnsen et a²¹ also found visual disturbances as most common complaints with macroadenomas.

Intrasellar extension with sellar enlargement was found in all cases. This finding was consistent with various other studies.^1112,22,23 There were 6 patients with lateral bulge of cavernous sinus (Knosp IV). This is the most sensitive sign to detect cavernous sinus invasion.^9,24,25 In literature²⁶ it has been stated that, visualization of medial wall of cavernous sinus rules out cavernous sinus invasion. However, the medial wall of the cavernous sinus is visible in only 27% of normal population²⁶. So, significance of this fact is that, absence of visualization of medial cavernous sinus wall can be noted even when the cavernous sinus invasion by pituitary macroadenoma is absent. In our study in no patients the medial cavernous wall could be visualized.

Displacement of the cavernous sinus without accompanying invasion is characterized by lateral displacement of the carotid siphon and compression of the medial compartment of the cavernous sinus with no enlargement of the superior, lateral, and inferior compartments. This sign has got sensitivity for ruling out cavernous sinus invasion, 66.66% and specificity of 83.33%. Thus, when it was present it was a reliable sign excluding cavernous sinus invasion. Suprasellar extension is seen in 42 out of 50 patients (84% cases.) Benjamin et al¹² and Johnsen et¹¹ al also have got similar findings.

Hemorrhage is noted in 14 (28 %) case of macroadenoma. Johnsen et al¹¹ found incidence of hemorrhage about 14% in 71 cases. In other large surgical series, the incidence of the hemorrhage was 17% in 560 patients²⁷. All cases were detected incidentally. This confirmed previously reported finding that, hemorrhage may present without clinical complaints.²⁸ Both cases showed hyperintense signal on T1W and T2W.Blooming signal was seen on gradient images.

In the present study, there were 10 patients of suprasellar craniopharyngiomas which constituted 10% of total patients. Johnsen et al¹ in their retrospective study noted 10(7.6%) cases of craniopharyngioma. In solid-cystic cases cystic component is iso to hyper on T1W & T2W images. Solid component is iso to hypo on T1W Isointense on T2W images. Solid lesions show mixed signal intensity on T1W & T2W images. On post contrast study cystic component show peripheral enhancement and solid portion show heterogenous enhancement. 8 of 10 craniopharyngiomas in our study were mixed solid cystic in morphology while 2 were solid. The postcontrast study was helpful in detecting cystic areas within such lesions, depicting as non-enhancing or peripherally enhancing areas.²⁹

The presence of calcification is noted in 6 (53%) cases. In a study by Pusey et al³⁰ which compared the CT and MRI in assessment of craniopharyngiomas, they found that, CT was superior to MR in demonstrating calcifications within the tumors. MR failed to demonstrate areas of calcification in three of 14 cases in which calcification was demonstrated by CT. In one case, calcification would have been incorrectly suspected on the basis of MR. Johnsen et al¹¹ also concluded that, CT provides superior demonstration of tumoral calcification and, hence, may permit a more specific diagnosis when this common characteristic is demonstrated. This is a circumstance in which CT assumes a particularly useful role as a diagnostic adjunct.

Although all were primarily suprasellar in location, all cases of craniopharyngiomas in our study showed intrasellar extension. Bony sellar wall erosion is seen is seen in 20% of cases. The sellar expansion was not as large as in pituitary adenomas. Only one case showed significant sellar expansion. Literature showed bony sellar wall erosion in 44% of cases of craniopharyngiomas³¹. One literature further stated that, if mass is centered in the sella with significant sellar expansion and bony erosion, the possibility of pituitary adenoma is likely. Our study also supported this hypothesis.³²

In our study, we found craniopharyngioma to be the most common tumor in sellar & juxtasellar region to be associated with hydrocephalus. (50% cases). This is related to the fact that the craniopharyngiomas tend to grow larger in size and cause more mass effect than any other lesion. Superior, lateral, posterior and inferior extensions of craniopharyngiomas are better demonstrated in contrast enhanced coronal sequences as in pituitary macroadenomas.

Meningiomas in sellar region may arise from tuberculum sellae, diaphragma sellae, clinoid processes, optic nerve sheaths and wings of sphenoid. Meningiomas in juxtasellar region may extend in to the sellar region. There were 5 surgically proved meningiomas in our study. Isointensity on T 1- and T2-weighted images is a characteristic signal intensity feature of meningiomas. With over 50% being isointense to cortex on TI- and T2-weighted images, but similar findings in macroadenomas make this feature of little use in differentiation. In our study, we found 4 out of 5(80%) meningiomas to be isointense on T1W and T2W images. Atypical features such as presence of hemorrhage and cystic components have also been described in literature.³³Hyperostosis may be evident as focally expanded bone, which may be hyperintense on T1weighted images due to fatty marrow. Thickened cortical bone does not produce any signal and consequently may not be as easily appreciated. In our study hyperostosis was present in 1 case of meningiomas. Hyperostosis is a commonly encountered feature of meningiomas in any location and has been reported in 34% of meningiomas involving the sella.³⁴ Hyperostosis may sometimes be seen in metastases and may rarely be mimicked by dense calcification associated with craniopharyngiomas and aneurysms³⁶, but true osseous thickening still remains highly specific for meningioma. Peritumoral oedema is seen in 3 out of 5 cases and was detected best on T2W and FLAIR images. Dural tail enhancement or the meningeal sign is commonly associated with meningiomas but is not entirely specific.³⁵ In our study 5(100%) out of 5 cases showed dural tail sign. Johnsen et al¹¹ also found presence of dural tail sign in 57% cases of meningioma and in no other lesion.

There was total 4 (4%) epidermoid cysts out of 100 cases. Johnsen et al³⁷ found total 2.3% cases of epidermoid cysts comprising the sellar juxtasellar masses. The fifth cranial nerve is the second most common site of intracranial neuroma and the most frequent cranial nerve tumor to cause parasellar mass.In our study we found one cases of trigeminal schwannoma in adult patients. They were isointense to brain on T1W and hyperintense on T2W images in course of trigeminal nerve. Intense enhancement noted on postcontrast study. Johnsen et al¹¹found total 2 cases in their study in paraselllar region with similar imaging findings. In our study there were two cases of the chordoma in sellar, parasellar and retrosellar region. both cases were adult. On T1W, they were iso to hypointense. On T2W images heterogeneous hyperintense with hypointense septations noted. On postcontrast study, strong heterogeneous enhancement is seen in both cases, blooming is seen in GRE suggestive of calcification. There was gross bony destruction seen possibly postoperative changes.one of the lesion predominantly involved left parasellar region with encasement of left cavernous sinus and left ICA. Johnsen et al¹¹ found two cases in their study with similar results. Our findings are also comparable with the larger series study on chordoma by Meyer et al^37,38.

Suprasellar tuberculomas were found in  two female patient who presented with convulsions headache and visual disturbances. Pituitary tuberculomas are rare, though they were not an uncommon finding in autopsy material reported in the early half of this century. In a review of reported cases of intrasellar tuberculoma, Arunkumar MJ et al³⁹ found that most have headache as the presenting complaint in addition to visual disturbances. We found one case of high-grade glioma in 8-year-old child presented with uncontrolled seizure. There was large mixed (solid cystic) lesion in suprasellar and juxtasellar region with sellar extension. On MRI we are not able to differentiate malignant germ cell tumor from high grade glioma. Similar findings are seen in study that large germinoma with leptomeningeal deposit may difficult to differentiate with high grade glioma on MRI⁴⁰. Similar finding also reported by Tuba Karagulle Kendi et al.⁴¹

In our study, 3 cases had a septic cause (Rhino cerebral mucor mycosis) attributable to cavernous sinus thrombosis. These presented with symptoms of fever and headache and vision loss. In T1 and T2 images, loss of flow void in ICA and cavernous sinus and bulging of lateral wall are predictors for thrombosis.^4,42

Limitations of our study

We used 1.5 T MR. 3 T MR spectroscopy is preferred in evaluation of sellar and juxtasellar regions and pituitary microadenoma. Role of Perfusion imaging, Magnetization Transfer Ratio and fMRI were not studied.          Traumatic, congenital lesions, metabolic disorders are not included in this study.Our hospital is tertiary care center, so most of patients were referred from other centers; this may affect statistical distribution.

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