| Part One Features about Position of Rathke's Cleft Cyst on MRI and Its Embryological BasisObjectives: To discuss the embryological basis of Rathke's Cleft Cyst(RCC)through an improved understanding of the cyst's position in reference to the pituitary gland on magnetic resonance imaging(MRI).Materials and methods: We retrospectively evaluated 90 patients with RCC,33 men and 57 women,with a mean age of 40.9 years.All the cysts were verified both surgically and histologically.All the RCCs were observed on MRI,focusing on shape,size,especially position in reference to the pituitary gland and pituitary stalk.The features about RCC's positionwere compared in patients with different sex,age and symptoms.Results:1 Shape,size and position of RCC in reference to the sella turcica: Most of the 90 RCCs had an intrasellar location,at least partially,with 43 lesions contained completely in the sella and having height of less than 1.2 cm.An additional 43 lesions were larger,with a height of more than 1.2 cm(maximum: approximately 2.8 cm),extending from the sella to the suprasellar region.There were only four lesions that were completely suprasellar in location.A round or ovoid shape was observed for 83 lesions,while the remaining seven had snowman appearances.2 Position of RCC in reference to the pituitary gland on the coronal view:There were two main types of position of the RCCs in reference to the pituitary gland on the coronal view.In some,the RCC was located in the middle of the pituitary gland(80 of 90,88.9%),and in the remainder,the RCC was located laterally(only 10,11.1%).There were no statistically significant differences about sex,age and symptoms between the two types(p = 0.132,0.283,0.286).3 Position of RCC in reference to the pituitary gland on the sagittal view:(1)We identified three position types for the RCC in reference to the anterior and posterior lobes of the pituitary gland.In 70 cases,the RCC was located between the anterior and posterior lobes of the pituitary gland(Type ?,77.8%),while in 13 it was located close to the anterior lobe ofthe pituitary gland and in front of the pituitary stalk(Type ?,14.4%).For seven cases of snowman-like cysts(Type ?,7.8%),the inferior portion of RCC was located between the anterior and posterior lobes of the pituitary gland,with the superior portion close to the anterior lobe of the pituitary gland and in front of the pituitary stalk.There were no statistically significant differences about sex,age and symptoms among these position types(p = 0.505,0.187,0.561).(2)We identified another three position forms for the RCC in reference to the pituitary stalk.Least frequently,the inferior peak of RCC's wall was located in front of the pituitary stalk(Form?,10 cases,11.1%).In others,the superior peak of RCC's wall was located behind the pituitary stalk(Form ?,50 cases,55.6%),while the superior margin of RCC was located across or encircled the pituitary stalk with a snowman appearance(Form ?,30 cases,33.3%).There were no statistically significant differences about sex,age among these position forms(p = 0.842,0.525),but symptoms differed between Form ? and ?(p = 0.007).Conclusion: There are different position features of RCC on MRI.The typical position of RCC on MRI is in the middle of pituitary on the coronal view,between the anterior and posterior lobes on the sagittal view,with the superior peak of cyst's wall lying behind or across the pituitary stalk.RCC's position is thought to be related to the Rathke's pouch,which is located between the anterior and posterior lobes of the pituitary gland,might be separated into supra-anterior and infra-posterior parts by the infundibulum during gestation.Part Two Value of the Lesion's Position for Diagnosis of Rathke's Cleft Cyst,a Comparison with Cystic Pituitary AdenomaObjectives: To identify Rathke's cleft cyst(RCC)through an improved understanding of the lesion's position,with comparison to the cystic pituitary adenoma(CPA).Material and methods: We retrospectively evaluated 124 patients with pituitary masses,dividing them into the RCC and CPA groups,which were verified both surgically and histologically.The RCC group included 90 patients,33 men and 57 women,with a mean age of 40.9 years.The CPA group included 34 patients,12 men and 22 women,with a mean age 43.5years.The lesions in both groups were observed and compared on MRI,focusing on the shape and size,as well as clinical and MRI features(including signal intensity on T1 and T2,presence of intracystic nodule or fluid-fluid level),especially position.Binary logistic regression analysis was adopted.Receivers operating characteristic(ROC)curves were drawnto evaluate the predictive models according to the predictive values obtained from the multivariate logistic regression analyses.Results:1 Shape,size and position of lesions:(1)The RCCs were of ovoid or snowman appearance.43 lesions contained completely in the sella,with a height of less than 1.2 cm.Another 43 lesions were larger,with a height of more than 1.2 cm,extending from the sella to the suprasellar region.There were only four lesions that were completely suprasellar in location.(2)All of the CPAs were ovoid,14 lesions were located completely within the sella,while 20 lesions extended from the intrasellar region to the suprasellar region.2 Comparison about clinical data between the RCC and CPA groups:There were no statistically significant differences about sex,age and symptoms between two groups(p = 0.487,0.887),but symptoms differed(p = 0.009).3 Comparison about signal features on MRI between the RCC and CPA groups: There were significant differences about signal intensity on T1 WI,presence of intracystic nodule and fluid-fluid level between two groups(p= 0.002,0.015,0.000),while no difference about T2 signal intensity(p =0.129).4 Comparison about position types of the lesion between the RCC and CPA groups: There were significant differences about the position types onthe coronal and sagittal view between two groups(p = 0.000,0.000).5 Multiparametric analysis with logistic regression showed that position on the sagittal and coronal views,fluid-fluid level and signal intensity on T1 WI were the most effective variations,the AUC is 0.906,0.856,0.583 and 0.692,respectively.The AUC of the logistic regression function was 0.955.With a cut-off value of p ? 0.553 for diagnosing RCC,the sensitivity and specificity were 0.933 and 0.912.Conclusion: RCC can be distinguished from CPA accurately based on its position in sagittal and coronal MRI.Part Three Posterior Pituitary Bright Spot on 3D TOF MRA and Detection of Posterior Pituitary's HypointensityObjectives: To evaluate detective ability and features of posterior pituitary bright spot(PPBS)of children through sequence of three dimensional time of flight magnetic resonance angiography(3D TOF MRA)at 3.0 T.Material and methods: We retrospectively evaluated 268 patients(146boys and 122 girls,with a medium age of 7 years old),who underwent brain MRI scan through conventional sequences(T1WI,T2WI)and 3DTOF MRA.No pituitary or endocrine symptoms were reported.The presence,shape and location of PPBS were assessed.Any low-TOF signal intensity was observed and recorded.Any pituitary feature on MRI was also recorded.The patients were divided into four groups by ages,which were infants,toddlers,preschoolers and older than school-age children.Also,?2-test was utilized to compare differences about the morphological and position types of PPBS in age groups or of different sex.Results:1 PPBS was detected in 100% of cases through 3D TOF MRA,only 10 cases failed to display on T1 WI,with a consistency of 96.7%.The interface of PPBS in reference to the anterior pituitary was convex(96 cases,35.8%),flat(103 cases,38.4%)or concave(104 cases,38.8%).164(61.2%)cases of PPBS were located behind the anterior pituitary in a midline,while the others were laterally located(38.8%).2 There were no statistical differences about the morphological and position types of PPBS among age groups(p = 0.066,0.724).3 There was no sex difference about the morphological types of PPBS(p= 0.566).However,sex difference existed in the position types(p = 0.007).4 Low-TOF signal intensity was detected in 53 cases of PPBS(19.8%).They were of different appearances,including 20 cysts(diameter 1.2 ~ 2.9mm),18 clefts(width 0.6 ~ 1.9 mm),7 wave incisures(width 2.7 ~ 5.1mm),4 arches(width 1.7 ~ 3.5 mm),and 4 cases of oblate shape(width 2.9~ 5.2 mm).The most common features about pituitary are hypointensity between the anterior and posterior lobes of the pituitary gland on 3D TOF MRA and/or sagittal T2 WI.Conclusion: 3D TOF MRA can be used to evaluate the posterior lobe of pituitary in children,as the high detection rate of 100%.The characteristics about shape and localization of the posterior pituitary were effectively observed.We firstly observed low-TOF signal intensity in PPBS,which is thought to be related to remnant of Rathke's pouch or the Rathke's cleft cyst. |
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