Analysis of 7-tesla diffusion-weighted imaging in the prediction of pituitary macroadenoma consistency

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>Endoscopic surgery is an effective treatment strategy for pituitary adenomas; however, intrinsic tumor properties such as tumor consistency can challenge or preclude gross-total resection. Preoperative characterization of tumor consistency may help to guide the surgical approach and to predict the extent of resection that is possible. Advanced radiological modalities such as 7T diffusion-weighted imaging (DWI) may be useful in probing biological tissue properties of pituitary adenomas. The objective of the present study was to examine 7T DWI as a novel method of measuring the consistency of pituitary adenomas.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>Thirteen patients with pituitary macroadenomas underwent 7T MRI, including a DWI image acquisition. Tumor apparent diffusion coefficient (ADC) was normalized to the adjacent temporal gray matter ADC. All patients underwent resection, and a single neurosurgeon blinded to ADC values rated tumor firmness from 1 (least firm) to 5 (most firm) using objective criteria. The tumor specimens were evaluated histopathologically for cellularity, collagen content, and vascularity by a neuropathologist who was also blinded to ADC values. The tumor ADC was correlated with intraoperative consistency rating, histopathology, and extent of resection. Receiver operating characteristic (ROC) curve analyses were performed to identify thresholds to predict tumor consistency.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>Corrected ADC values were significantly correlated with both tumor firmness (r <jats:italic>=</jats:italic> −0.60, p = 0.029) and the extent of trichrome staining (r <jats:italic>=</jats:italic> −0.72, p = 0.009) such that greater ADC values were associated with both decreased tumor firmness and decreased collagen staining. Correlations between ADC values and tumor vascularity were not significant (r <jats:italic>=</jats:italic> −0.09, p = 0.78). Corrected ADC values in totally resected tumors (1.54) were greater than those in subtotally resected tumors (0.85) (p = 0.02), and ADC values were greater with moderate tumor cellularity (1.51) than with high tumor cellularity (0.8) (p = 0.035). There was a trend-level association for partial resections to exhibit greater tumor firmness rating (3 vs 1.7; p = 0.051). Finally, the degree of trichrome staining positively correlated with tumor firmness (r <jats:italic>=</jats:italic> 0.60, p = 0.04). The optimal threshold for predicting intraoperative consistency rating was an ADC ratio of 0.87 (sensitivity 80%, specificity 100%, area under the curve [AUC] 0.90; p = 0.043). The optimal cutoff for distinguishing the extent of resection was 1.19 (sensitivity 85.7%, specificity 83.3% AUC 0.833; p = 0.046).</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>The authors’ results suggest that a high-resolution ADC of pituitary adenomas is a sensitive measure of tumor consistency. 7T DWI may hold clinical value in the preoperative workup and surgical management of patients with pituitary macroadenomas.</jats:p></jats:sec>

Primary Endoscopic Endonasal Management of Giant Pituitary Adenomas: Outcome and Pitfalls from a Large Prospective Multicenter Experience

“…Thirty-one GPAs (32.3%) were deemed to have significant vascularization due to profuse intraoperative bleeding impairing visualization through the endoscopic lens and requiring more than 20 mL of advanced hemostatic matrix, whereas the remaining 65 GPAs (67.7%) did not. Interestingly, our results are in keeping with the data reported by previous studies [ 11 , 12 ], confirming that 2/3 of GPAs are not highly vascularized. EoR was classified as follows: GTR in 34 cases (35.4%) ( Figure 1 ), NTR in 12 cases (12.5%) ( Figure 2 ), and STR in 50 (52.1%) ( Figure 3 and Figure 4 ).…”

“…EoR was classified as follows: gross total resection (GTR) 100% of the initial tumor volume, near total resection (NTR) between 96 and 99% of the initial tumor volume, subtotal resection (STR) between 75 and 95% of the initial tumor volume. Tumor consistency was assessed by at least two surgeons, either intraoperatively or revising surgical videos: it was defined as soft if GPA was resectable with conventional curettage and suction, or firm/fibrous if more resistant to these maneuvers and requiring some degree of mechanical debulking and/or extracapsular dissection [ 11 , 12 ]. Vascularization was also assessed intraoperatively and on video recordings as significant or non-significant depending on degree of intraoperative bleeding appreciated through the endoscopic lens.…”

“…Institutional Review Board Statement: This study was approved by the Interregional Ethic Committee (IRB N • 2861), and it was conducted in accordance with the Principles of Ethics for Medical Research Involving Human Subjects set in the Declaration of Helsinki and its subsequent amendments. To report our results, we followed the recommendations of the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement for observational studies [11].…”

Effect of pituitary adenoma consistency on surgical outcomes in patients undergoing endonasal endoscopic transsphenoidal surgery

“…The consistency of PAs has not been analyzed in-depth in recent literature [2]- [4]. Most PAs are considered to be soft in consistency, facilitating complete excision.…”

Differentiating between non-functioning pituitary macroadenomas and sellar meningiomas using ADC

“…However, the aforementioned methods sometimes may not lead to a confirmed etiological diagnosis because of the uncertainty of the origin of a lesion ( 13 ). Diffusion-weighted imaging (DWI) can noninvasively provide information concerning high signal-intensity regions as areas of increased cellularity and tissue microstructures by measuring water diffusion within a tissue ( 14 , 15 , 16 ), which is closely associated with membrane integrity and cell density ( 15 , 17 ). The diffusion of water molecules is determined by a high cellularity, a small extracellular space, and a high nuclear-to-cytoplasmic ratio ( 18 ).…”