Image Negative (MR negative) Cushing Disease: A Call to Standardize the Term and Guide to Convey Imaging Certainty.

1H-MR Spectroscopy as a Decision-Support Tool in the Differential Diagnosis of Intracranial Lesions: A Real-World Bicentric Retrospective Cohort

Purpose: To evaluate whether proton MR spectroscopy (1H-MRS) improves the differentiation of tumoral from non-tumoral intracranial lesions beyond conventional MRI, and to quantify its effect on diagnostic confidence, in a consecutive real-world bicentric cohort of diagnostically ambiguous lesions. Methods: This retrospective, bicentric observational study screened 122 consecutive patients who underwent brain MRI with 1H-MRS at two imaging centers, of whom 99 were eligible for final analysis after excluding 23 patients due to insufficient follow-up (<12 months) or incomplete reference standard. The reference standard was histopathological confirmation in 43 cases (43.4%) and structured clinico-radiological follow-up of at least 12 months in 56 cases (56.6%). The reporting radiologist’s binary diagnostic impression and confidence score were recorded before and after 1H-MRS. Conventional MRI alone was compared to MRI plus 1H-MRS using the exact McNemar test; Cho/NAA discrimination was assessed by ROC analysis with bootstrap confidence intervals, and confidence change by the Wilcoxon signed-rank test. Secondary analyses comprised an intention-to-diagnose analysis of all 99 examinations, counting non-diagnostic spectra as test failures, and an evaluable-case sensitivity analysis restricted to histopathologically confirmed patients with interpretable spectra. Results: Of 99 examinations, 89 (89.9%) yielded interpretable spectra. In the primary analysis, qualitative MRS interpretation demonstrated sensitivity of 76.0% (95% CI: 61.8–86.9), specificity of 94.9% (95% CI: 82.7–99.4), and accuracy of 84.3% (CI: 75.0–91.1), compared with 54.0%, 89.7% and 69.7% (59.0–79.0) for conventional MRI alone (exact McNemar p = 0.024). ROC analysis of the Cho/NAA ratio (n = 89) yielded an AUC of 0.858 (0.774–0.931); the exploratory, cohort-specific Youden-optimal cut-off was 1.41 (sensitivity 78.0%, specificity 87.2%). In the intention-to-diagnose analysis including all 99 examinations, accuracy was 78.8% (69.4–86.4). Diagnostic confidence increased significantly after 1H-MRS (median 1 to 2; Wilcoxon p < 0.001; effect size r = 0.81), with moderate or major added value in 71 of 99 examinations (71.7%). Conclusions: In a diagnostically heterogeneous real-world cohort, 1H-MRS significantly improved the accuracy achievable with conventional MRI alone and substantially increased reported diagnostic confidence, with high specificity but only moderate sensitivity. A zone-based Cho/NAA interpretative framework better reflects biological overlap than rigid binary thresholds. As this study assessed diagnostic accuracy and reported confidence rather than therapeutic decisions or patient outcomes, 1H-MRS should be regarded as an adjunctive decision-support modality rather than a standalone classifier in routine neuro-oncologic workflows.

The clinical utility of magnetic resonance elastography in differentiating tumor recurrence from pseudoprogression in glioblastoma.

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults with nearly universal progression despite aggressive treatment. Distinguishing true tumor recurrence from treatment-related effects (pseudoprogression) remains challenging with conventional contrast-enhanced MRI, as both can produce similar imaging findings. Magnetic resonance elastography (MRE), which measures tissue stiffness, has shown that gliomas are less stiff than normal brain parenchyma and that stiffness inversely correlates with tumor grade. We hypothesized that MRE could differentiate true tumor progression from treatment effects in post-treatment GBM patients. This retrospective pilot study included 13 patients with pathology-confirmed GBM who demonstrated imaging findings suspicious for recurrence on surveillance MRI. MRE was performed as an add-on sequence requiring less than 7 min of additional scan time. Regions of interest (ROIs) were manually delineated by a single neuroradiologist blinded to progression status and compared to contralateral control regions. Progression status was determined by pathologic confirmation when available or by clinical history and imaging characteristics. Among 18 analyzed lesions from 13 patients, a linear mixed effects model revealed a significant interaction between progression status (true progression or pseudoprogression) and ROI (lesion or contralateral control) on tissue stiffness (coef = -0.174 kPa, z = -12.75, p < 0.001). True tumor progression demonstrated significantly reduced stiffness compared to contralateral control tissue, while the majority of pseudoprogression lesions showed no significant stiffness reduction. MRE-derived stiffness measurements may serve as a useful imaging biomarker to distinguish GBM recurrence from treatment effects, potentially complementing perfusion MRI in guiding clinical decision-making for post-treatment GBM patients.

Interobserver agreement in MRI assessment of pancreatic cystic neoplasms: a retrospective single-center study.

Diagnostic performance of 3T MRI preoperative localization of parathyroid adenomas in primary hyperparathyroidism

Preoperative localization is essential for the surgical management of primary hyperparathyroidism (PHPT). Ultrasound and 99mTc-sestamibi SPECT/CT are first-line imaging modalities, while MRI’s role is less defined. This study aimed to evaluate MRI for parathyroid adenoma localization in PHPT and compare it with that of ultrasound and SPECT/CT. In this prospective single-center study, 103 adults with biochemically confirmed PHPT underwent ultrasound, multiparametric 3T MRI, and SPECT/CT before surgery. MRI examinations were independently evaluated independently evaluated by two blinded radiologists. Surgical and histopathological findings served as the reference standard. Ninety-three patients (90%) had single-gland disease (SGD), and 10 (10%) multiglandular disease (MGD). MRI demonstrated high sensitivity for adenomas in SGD but significantly lower sensitivity in MGD: Reader 1, 0.824 vs 0.476 (p = 0.002) and Reader 2, 0.890 vs 0.524 (p < 0.001). Ultrasound and SPECT/CT showed similar patterns. Specificity did not differ significantly between SGD and MGD. Inter-reader agreement was high for MRI and ultrasound (Krippendorff’s α > 0.8) but decreased when including SPECT/CT. MRI-based size lesion size measurements showed good concordance between readers (ρC = 0.822) but showed low concordance with histology (ρC1 = 0.498; ρC2 = 0.373) due to systematic underestimation (15–18%). Multiparametric 3T MRI provides localization sensitivity to that of first-line imaging modalities in SGD, but differentiation between MGD and SGD remains challenging, with MRI showing no clear superiority over standard modalities.

Imaging MRI biomarkers for diagnosing brain radionecrosis: focus on incomplete ring enhancement sign.

PURPOSE Differentiating brain radionecrosis from recurrent metastases after radiotherapy remains challenging because no single imaging technique is definitive. This study evaluated the diagnostic accuracy of the incomplete ring enhancement sign (IRES) on contrast-enhanced 3D T1-weighted gradient-echo MRI (CE 3D T1 GRE) as a diagnostic sign of radionecrosis and analyzed associated morphologic features. METHODS In this retrospective case-control study, 45 cases of radionecrosis were identified from an institutional database of 1,179 brain metastases consecutively treated with stereotactic radiotherapy (2015-2022). Ninety CE 3D T1 GRE examinations were reviewed in blinded fashion: 45 radionecrosis examinations and 45 matched pre-treatment-naïve metastases from the same patients. The presence of IRES was assessed, and diagnostic performance was calculated. Interobserver agreement was evaluated using Fleiss's kappa. Fragmentation, satellite lesions, and lesion distribution were compared using χ². RESULTS Mean sensitivity and specificity against treatment-naïve metastases were 97% (95% CI, 87-99) and 76% (95% CI, 61-88), respectively. Interobserver agreement was substantial (κ = 0.75). IRES was already present in 50% of the MRIs in which radionecrosis was first suspected. Fragmentation occurred in 89% of radionecrosis cases versus 2% of metastases (p < 0.001), and satellite lesions in 29% versus 2% (p < 0.001). Watershed localization was found in 83% of supratentorial radionecrosis. Because the control group consisted of treatment-naïve metastases rather than post-radiotherapy recurrences, the reported accuracy should be interpreted as proof-of-concept. CONCLUSION The incomplete ring enhancement sign is a potential diagnostic sign of brain radionecrosis. Fragmentation, satellite foci, and watershed localization may reinforce the diagnosis.

Clinical management challenges of Cushing’s disease associated with double pituitary adenomas: four cases and literature review