Postoperative Imaging of the Temporal Bone.

The anatomy of the temporal bone is complex, and postoperative imaging evaluation of this bone can be challenging. Surgical approaches to the temporal bone can be categorized didactically into tympanoplasty and ossicular reconstruction, mastoidectomy, and approaches to the cerebellopontine angle and internal auditory canal (IAC). In clinical practice, different approaches can be combined for greater surgical exposure. Postoperative imaging may be required for follow-up of neoplastic lesions and to evaluate unexpected outcomes or complications of surgery. CT is the preferred modality for assessing the continuity of the reconstructed conductive mechanism, from the tympanic membrane to the oval window, with use of grafts or prostheses. It is also used to evaluate aeration of the tympanic and mastoid surgical cavities, as well as the integrity of the labyrinth, ossicular chain, and tegmen. MRI is excellent for evaluation of soft tissue. Use of a contrast-enhanced fat-suppressed MRI sequence is optimal for follow-up after IAC procedures. Non-echo-planar diffusion-weighted imaging is optimal for detection of residual or recurrent cholesteatoma. The expected imaging findings and complications of the most commonly performed surgeries involving the temporal bone are summarized in this review. Online supplemental material is available for this article. ©RSNA, 2021.

Asymmetric cortical degenerative syndromes: an integrated approach to clinical and imaging review.

BACKGROUND: The term asymmetric cortical degenerative syndromes (ACDSs) refers to any brain afflictions that result in selective atrophy, particularly with an asymmetric pattern. Regardless of the etiology, the resulting compromised profile reflects the affected topography, which correlates with the clinical findings, more than any specific neuropathologic entity. REVIEW SUMMARY: ACDS can represent a diagnostic challenge, because of an overlap of clinical manifestations, especially in the early stages. Magnetic resonance techniques are useful to understand nuclear medicine studies and to confirm areas of focal atrophy by providing anatomic details and allowing an accurate correlation with several different clinical settings. CONCLUSIONS: This article demonstrates a practical neuroradiologic approach for ACDS, including optimized imaging analysis (magnetic resonance and nuclear medicine studies), which correlates their patterns with clinical and pathologic findings of the most relevant disorders.

The role of magnetic resonance imaging in the postoperative management of cholesteatomas.

UNLABELLED: Conventional CT and MRI scans have low specificity when it comes to differentiating granulation tissue from relapsing cholesteatoma. AIM: this paper aims to analyze the use of DWI and delayed post-contrast T1-weighed imaging in the detection of recurring cholesteatomas. MATERIALS AND METHOD: this is a cross-sectional prospective study that looked at 17 cholesteatoma patients postoperatively. All patients underwent diffusion magnetic resonance imaging at 1.5T, T1, T2, and delayed post-contrast T1 and images were produced from both coronal and axial planes. Two radiologists assessed the images and decided consensually that the presence of hyperintensive signal in DWI on T2, iso/hypointensive signal on T1, and absence of contrast uptake were indicative of relapsing cholesteatoma. Surgical review findings were compared to DWI scans. RESULTS: eleven of the twelve cases of recurring cholesteatoma presented hyperintensive signal in the DWI scans. None of the patients with granulation tissue in the surgical wound presented hyperintensive signal in the DWI scans. A patient with an abscess in the internal acoustic meatus also presented a hyperintensive signal in the DWI scans. Sensibility, specificity, positive predictive value and negative predictive value were 91.6%, 60.0%, 84.6%, and 75.0%, respectively. CONCLUSION: DWI combined with delayed post-contrast T1 SE sequence proved to be useful in the differential diagnosis of granulation tissue and recurring cholesteatoma.

Aplicação da ressonância magnética no acompanhamento da cirurgia do colesteatoma / The role of magnetic resonance imaging in the postoperative management of cholesteatomas

A tomografia computadorizada e ressonância magnética (RM) com seqüências convencionais têm baixa especificidade para a diferenciação entre tecido de granulação e recidiva de colesteatoma. OBJETIVO: Avaliar a aplicação da RM com sequência de difusão e pós-contraste T1 tardio na detecção de recidiva de colesteatoma. MATERIAL E MÉTODO: Realizado estudo transversal prospectivo de dezessete pacientes estudados no pós-operatório de colesteatoma utilizando RM de 1.5 T com seqüência difusão, T1, T2 e pós-contraste T1 tardio nos planos coronal e axial. Dois radiologistas avaliaram e decidiram em consenso a presença de foco de hipersinal na difusão e T2, iso/hipossinal em T1 e ausência de impregnação pelo contraste como suspeitos de recidiva de colesteatoma. Os achados da revisão cirúrgica foram comparados com o resultado da RM. RESULTADOS: Onze dos doze casos de recidiva de colesteatoma apresentaram hipersinal na difusão. Todos os pacientes com tecido de granulação na cavidade cirúrgica não apresentaram alteração de sinal na difusão. Um paciente com abscesso no conduto auditivo interno também apresentou hipersinal na difusão. A sensibilidade, especificidade, valor preditivo positivo e negativo foram respectivamente 91,6 por cento, 60 por cento, 84,6 por cento e 75 por cento. CONCLUSÃO: A seqüência de difusão combinada com pós-contraste tardio pode ser útil na diferenciação entre tecido de granulação e recidiva de colesteatoma.

Conventional CT and MRI scans have low specificity when it comes to differentiating granulation tissue from relapsing cholesteatoma. AIM: this paper aims to analyze the use of DWI and delayed post-contrast T1-weighed imaging in the detection of recurring cholesteatomas. MATERIALS AND METHOD: this is a cross-sectional prospective study that looked at 17 cholesteatoma patients postoperatively. All patients underwent diffusion magnetic resonance imaging at 1.5T, T1, T2, and delayed post-contrast T1 and images were produced from both coronal and axial planes. Two radiologists assessed the images and decided consensually that the presence of hyperintensive signal in DWI on T2, iso/hypointensive signal on T1, and absence of contrast uptake were indicative of relapsing cholesteatoma. Surgical review findings were compared to DWI scans. RESULTS: eleven of the twelve cases of recurring cholesteatoma presented hyperintensive signal in the DWI scans. None of the patients with granulation tissue in the surgical wound presented hyperintensive signal in the DWI scans. A patient with an abscess in the internal acoustic meatus also presented a hyperintensive signal in the DWI scans. Sensibility, specificity, positive predictive value and negative predictive value were 91.6 percent, 60.0 percent, 84.6 percent, and 75.0 percent, respectively. CONCLUSION: DWI combined with delayed post-contrast T1 SE sequence proved to be useful in the differential diagnosis of granulation tissue and recurring cholesteatoma.

Lactate detection by MRS in mitochondrial encephalopathy: optimization of technical parameters.

Mitochondriopathies are a heterogeneous group of diseases with variable phenotypic presentation, which can range from subclinical to lethal forms. They are related either to DNA mutations or nuclear-encoded mitochondrial genes that affect the integrity and function of these organelles, compromising adenosine triphosphate (ATP) synthesis. Magnetic resonance (MR) is the most important imaging technique to detect structural and metabolic brain abnormalities in mitochondriopathies, although in some cases these studies may present normal results, or the identified brain abnormalities may be nonspecific. Magnetic resonance spectroscopy (MRS) enables the detection of high cerebral lactate levels, even when the brain has normal appearance by conventional MR scans. MRS is a useful tool for the diagnosis of mitochondriopathies, but must be correlated with clinical, neurophysiological, biochemical, histological, and molecular data to corroborate the diagnosis. Our aim is to clarify the most relevant issues related to the use of MRS in order to optimize its technical parameters, improving its use in the diagnosis of mitochondriopathies, which is often a challenge.