Evaluation of Consistency of Pituitary Macroadenoma Using Diffusion-weighted Imaging in Correlation With Surgical Findings

Abstract

Objective: The consistency of pituitary macroadenomas can be a confounding factor during transnasal transsphenoidal decompression, often necessitating incomplete removal and need for a transcranial approach for complete tumor excision. Very few studies have evaluated preoperative tumor consistency in relation to imaging findings. Our objective was to determine whether conventional magnetic resonance images and diffusionweighted (DW) imaging with apparent diffusion coefficient (ADC) maps are predictive of the consistency of pituitary macroadenomas.Methods: A retrospective study of 31 patients who had undergone surgery for pituitary macroadenoma in our hospital. Preoperative magnetic resonance images were reviewed and regions of interest were drawn on the macroadenoma and normal white matter on DW images independently by 2 neuroradiologists. Consistency of macroadenomas was determined from the surgical records and was classified into soft, intermediate, or hard. Mean ADC values, signal intensity ratio of tumor to white matter within regions of interest on conventional and DW images, and degree of enhancement were compared with tumor consistency using analysis of variance.Results: The mean ADC values in the soft group was 0.754 Â 10 À 3 mm 2 /s, in the intermediate group was 0.963 Â10 À 3 mm 2 /s, and in the hard group was 1.312 Â 10 À 3 mm/s. Statistical analysis revealed a significant correlation between consistency and ADC values (P < 0.004). There was no significant association between tumor consistency and signal intensity or degree of contrast enhancement. Conclusions:The findings in this study suggest that DW images with ADC maps are useful for preoperative prediction of consistency of pituitary macroadenomas. E ndoscopic transsphenoidal technique has been widely accepted as the modality of choice for removing pituitary tumors. 1-4 This technique is minimally invasive and incidence of postoperative complications is less compared with the traditional microscopic decompression. 5 But this procedure has got its own limitations in certain conditions like sphenoid sinusitis and ectatic midline carotid arteries, where transcranial approach is preferred. 6 Another important factor that determines the outcome and the method of approach is the tumor consistency. 7,8 Approximately 5% to 14% of pituitary macroadenomas are firm and fibrous, thus not compliant to suction/curettage, which makes total excision of the tumor difficult. This would necessitate a second transcranial approach for complete tumor removal. Information about the consistency of tumor before surgery helps the surgeon plan accordingly, thus avoiding an unnecessary second procedure and also helps to bring down the cost and complications.The conventional magnetic resonance imaging (MRI) findings, previously described in literature, indicating the consistency of tumor included T2-weighted hypointensity and homogenous enhancement as a marker of fibrous lesions. 9,10 This finding is controversial and not always consistent with surgical findings. 11,12 Diffus...

Magnetic resonance elastography detects tumoral consistency in pituitary macroadenomas

“…They found no correlation between the appearance of macroadenomas and T2W MRI appearance. Several of the above studies have concluded the same [6,14,15]. …”

“…Mahmoud et al also concluded ADC values did not correlate with operative consistency. In contrast, both Pieralliniet et al [4] and Thomas et al [15] reported a correlation between PMA consistency and ADC values.…”

Virtual magnetic resonance elastography has the feasibility to evaluate preoperative pituitary adenoma consistency

“…Also, no correlation between T2-weighted image characteristics and PA consistency has been found [ 17 ]. A few studies have correlated standardized diffusion weighted imaging to PA consistency [ 8 , 18 ], but found that the calculated diffusion value is not predictive of tumor consistency [ 19 ]. This might, to some part, be assigned to perfusion that inherently contaminates the diffusion value.…”

Prevalence and Imaging-Based Classification of Pituitary Adenomas with Hard Consistency: A Systematic Review and Meta-Analysis

“…One of the earliest studies to examine the utility of tissue water diffusion measurement hypothesized that diffusion-weighted imaging (DWI) combined with ADC maps might predict pituitary tumor consistency and guide the acceptance of endoscopic methods [14]. Tumors with hard consistency initially had higher ADC values than pituitary adenomas that were easily aspirated [14,[25][26][27]. However, over the years, contradictory results have surfaced [13,18,24,28,29], with the majority of studies nding a link between lower ADC values and hard consistency [28,[30][31][32].…”

“…Researchers agree that hard tumors have more homogeneous patterns, whereas a more varied pattern or the presence of hyperintense dots favors the diagnosis of soft tumors. Numerous studies have attempted to employ quantitative SI to discriminate tumor consistency and provide a more accurate method, with all but one [36] failing to demonstrate a positive association [14,18,23,25]. Comprehensive magnetic resonance imaging evaluation textural analysis, which re ects the spatial distribution of gray levels and SI in co-occurrence matrices, is a promising strategy for overcoming variation within the sample and has been proposed as an alternative tool for determining adenoma consistency preoperatively [35].…”