Superiority of constructive interference in steady-state MRI sequencing over T1-weighted MRI sequencing for evaluating cavernous sinus invasion by pituitary macroadenomas

Novel imaging techniques in refractory pituitary adenomas

Accurate localization of the site(s) of active disease is key to informing decision-making in the management of refractory pituitary adenomas when autonomous hormone secretion and/or continued tumor growth challenge conventional therapeutic approaches. In this context, the use of non-standard MR sequences, alternative post-acquisition image processing, or molecular (functional) imaging may provide valuable additional information to inform patient management.

Pituitary Adenomas: Classification, Clinical Evaluation and Management

Pituitary adenomas are one of the most common brain tumors. They represent approximately 18% of all intracranial, and around 95% of sellar neoplasms. In recent years, our understanding of the pathophysiology and the behavior of these lesions has led to better control and higher curative rates. The treatment decision is largely dependent on type of the adenoma, clinical presentation, and the size of the lesion. In addition, incidental pituitary lesions add uncertainty in the decision-making process, especially for pituitary adenomas that can be medically managed. When surgery is indicated, the endoscopic endonasal transsphenoidal approach is the technique of choice, but open standard craniotomy approaches can also be the option in selected cases. The following chapter will review the classification, clinical presentation, pathophysiology, diagnostic work-up, selection of surgical approach, and treatment complications in pituitary adenomas.

A Convolutional Neural Network Model for Detecting Sellar Floor Destruction of Pituitary Adenoma on Magnetic Resonance Imaging Scans

Objective

Convolutional neural network (CNN) is designed for image classification and recognition with a multi-layer neural network. This study aimed to accurately assess sellar floor invasion (SFI) of pituitary adenoma (PA) using CNN.

Methods

A total of 1413 coronal and sagittal magnetic resonance images were collected from 695 patients with PAs. The enrolled images were divided into the invasive group (n = 530) and the non-invasive group (n = 883) according to the surgical observation of SFI. Before model training, 100 images were randomly selected for the external testing set. The remaining 1313 cases were randomly divided into the training and validation sets at a ratio of 80:20 for model training. Finally, the testing set was imported to evaluate the model performance.

Results

A CNN model with a 10-layer structure (6-layer convolution and 4-layer fully connected neural network) was constructed. After 1000 epoch of training, the model achieved high accuracy in identifying SFI (97.0 and 94.6% in the training and testing sets, respectively). The testing set presented excellent performance, with a model prediction accuracy of 96%, a sensitivity of 0.964, a specificity of 0.958, and an area under the receptor operator curve (AUC-ROC) value of 0.98. Four images in the testing set were misdiagnosed. Three images were misread with SFI (one with conchal type sphenoid sinus), and one image with a relatively intact sellar floor was not identified with SFI.

Conclusion

This study highlights the potential of the CNN model for the efficient assessment of PA invasion.

Diagnostic value of Knosp grade and modified Knosp grade for cavernous sinus invasion in pituitary adenomas: a systematic review and meta-analysis

OBJECTIVE

This study aimed to examine the reliability of existing Knosp grade (KG) and modified KG for cavernous sinus invasion (CSI).

METHODS

A thorough search of literature from 1993 to 2020 in six databases was performed. Studies that reported the intraoperative confirmation of CSI using KG and/or modified KG were included. The pooled estimates were calculated by meta-analysis with a bivariate mixed-effect model and the assessment of heterogeneity with I² statistic.

RESULTS

The final search yielded 12 eligible studies, which enrolled 3006 patients assessed with KG and 1315 patients assessed with modified KG. The results of the area under the receiver operating characteristic curve showed the good discriminative abilities of grades 2-4 (0.90), 3-4 (0.86) and 3B-4 (0.91) in predicting CSI. Grade 3A showed a remarkably lower CSI rate (44% versus 81%) and incomplete resection rate (26% versus 52%) than grade 3B. Grades 0 and 1 showed a low CSI rate. CSI and incomplete resection rates in grade 2 (30% and 21%, respectively) were close to those in grade 3A.

CONCLUSIONS

Modifying the KG improved its prognostic role in CSI and gross total resection. However, these grading systems cannot be used as the group standard for invasive and non-invasive pituitary adenomas (PAs) because of the weak reliability of the scale's middle grades (grades 2 and 3A). Authors of future PA studies should consider reporting KG as high (grades 3B and 4), medium (grades 2 and 3A) and low (grades 0 and 1) to optimise the application of the scale.

Accuracy and Interrater Reliability of CISS Versus Contrast-Enhanced T1-Weighted VIBE for the Presence of Optic Canal Invasion in Tuberculum Sellae Meningiomas

BACKGROUND

The magnetic resonance imaging sequence used to assess optic canal invasion by tuberculum sella meningiomas (TSMs) has not been standardized. Both constructive interference in steady state (CISS) and contrast-enhanced T1-weighted volume-interpolated breath-hold examination (VIBE) sequences are frequently used. The aim of the present study was to compare the accuracy and interrater reliability of these sequences in predicting optic canal invasion by TSMs.

METHODS

In the present retrospective study of 27 patients (54 optic canals) who had undergone endoscopic transtuberculum transplanum resection of TSMs, images from preoperative CISS and contrast-enhanced T1-weighted VIBE sequences were assessed by 5 neuroradiologists who were unaware of the operative findings. The readers evaluated the optic canal in 4 quadrants at 2 locations (the posterior tip of the anterior clinoid process and the optic strut). A quadrant was considered positive for tumor invasion if invasion was present at either of these 2 locations. The reference standard was intraoperative observation of gross optic canal invasion.

RESULTS

The interrater agreement was good for the presence or absence of tumor involvement in a particular quadrant (CISS, 0.635; VIBE, 0.643; 95% confidence interval for the difference, -0.086 to 0.010). The mean sensitivity and specificity for optic nerve invasion were 0.643 and 0.438 with CISS and 0.643 and 0.454 with VIBE, respectively. No significant differences were seen between the sequences in terms of reader accuracy when the intraoperative findings were used as the reference standard.

CONCLUSION

CISS and VIBE sequences both have good accuracy in predicting for optic canal tumor invasion by TMEs.

Optimizing MR imaging for intraoperative image guidance in sellar pathologies

PURPOSE

With the advancement of extended endonasal approaches, the ability to surgically reach parasellar tumor extensions increase. The aim of the study was to propose an optimized imaging protocol for surgical guidance in the cavernous sinus (CS) for proper visualization structures at risk.

METHODS

Prospective case control analysis of 20 consecutive pituitary adenoma patients scheduled for endoscopic transnasal surgery. Assessment of the capability of three different MRI sequences (MPRAGE, VIBE, CISS) by 4 investigators to correctly visualize sellar and parasellar structures. Invasiveness and position of the normal pituitary gland were compared with the intraoperative findings.

RESULTS

The consensus between the 4 examiners to achieve the same results for all modalities was 40% for MPRAGE, 70% for VIBE and 60% for CISS sequences (p = 0.155). A consensus of Knosp Grade per patient was 80% for MPRAGE, 100% for VIBE and 90% for CISS (overall kappa 0.60). A higher Knosp Grade was found in MPRAGE sequences compared to the other sequences. Intraoperative status of invasiveness was correctly identified in 12/20 (60%) with MPRAGE, 19/20 (95%) with VIBE and 11/20 (55%) with CISS sequences. The position of the normal pituitary gland was most frequent evaluable in 15/20 (75%) and correctly identified in 12/15 (80%) cases.

CONCLUSION

Our data showed that VIBE sequences obtain the highest degree of consensus with intraoperative findings of invasiveness and position of the normal pituitary gland. VIBE sequences, due to their high spatial resolution and at the same time fast image acquisition could provide improved imaging for neuronavigation.

Comparison of Constructive Interference in Steady-State and T1-Weighted MRI Sequence at Detecting Pituitary Adenomas in Cushing's Disease Patients

Background  T1-weighted magnetic resonance imaging (MRI) remains the standard pituitary imaging sequence. However, up to 50% of pituitary adenomas are missed with standard imaging in Cushing's disease (CD) patients. Utility of other imaging sequences needs be explored. Objective  To compare a T2-gradient echo sequence, constructive interference in steady state (CISS), with a contrast-enhanced (CE) T1-weighted sequence, volume-interpolated breath-hold examination (VIBE), in the detection of pituitary adenomas in CD patients. Design  Retrospective analysis of CD patients who underwent endoscopic transsphenoidal pituitary adenomectomy at our institution. Patients and Measurement  Twelve patients were included in the study. Two neuroradiologists, who were blinded to the patients' clinical and surgical findings, independently reviewed the CE-VIBE and CISS images. Localization of pituitary adenoma from imaging was compared with intraoperative localization. Results  The averaged sensitivity of detecting pituitary adenoma in CD patients was not significantly different between CE-VIBE sequence (63%) and CISS sequence (54%). The positive predictive value was 75% (Observer A) and 100% (Observer B) with CE-VIBE sequence, and 64% (Observer A) and 100% (Observer B) with CISS sequence. In two patients, pituitary adenoma was easily localized with CISS sequence but hard to detect with CE-VIBE sequence. In two other patients, the adenoma was much better delineated on CE-VIBE sequence. Conclusion  In our series, the addition of CISS sequence to T1-weighted MRI imaging protocols improved the detection of pituitary adenomas in CD patients. CISS sequence may be a useful adjunct to T1-weighted pituitary MRI protocols and an appropriate alternative for patients with gadolinium contraindications.