Imaging of COVID-19-associated craniofacial mucormycosis: a black and white review of the "black fungus".

A subset of diabetic COVID-19 patients treated with steroids, oxygen, and/or prolonged intensive care admission develop rhino-orbito-cerebral mucormycosis. Radiologists must have a high index of suspicion for early diagnosis, which prompts immediate institution of antifungal therapy that limits morbidity and mortality. Assessment of disease extent by imaging is crucial for planning surgical debridement. Complete debridement of necrotic tissue improves survival. Imaging features reflect the angioinvasive behaviour of fungal hyphae from the Mucoraceae family, which cause necrotising vasculitis and thrombosis resulting in extensive tissue infarction. Contrast-enhanced magnetic resonance imaging (MRI) is the imaging technique of choice. The classic "black turbinate" on contrast-enhanced imaging represents localised invasive fungal rhinosinusitis (IFRS). A striking radiological feature of disseminated craniofacial disease is non-enhancing devitalised and necrotic soft tissue at the orbits and central skull base. Sinonasal and extrasinonasal non-enhancing lesions in IFRS are secondary to coagulative necrosis induced by fungal elements. Multicompartmental and extrasinonasal tissue infarction is possible without overt bone involvement and caused by the propensity of fungal elements to disseminate from the nasal cavity via perineural and perivascular routes. Fungal vasculitis can result in internal carotid artery occlusion and cerebral infarction. Remnant non-enhancing lesions after surgical debridement portend a poor prognosis. Assessment for the non-enhancing MRI lesion is crucial, as it is a sole independent prognostic factor for IFRS-specific mortality. In this review, we describe common and uncommon imaging presentations of biopsy-proven rhino-orbito-cerebral mucormycosis in a cohort of nearly 40 COVID-19 patients.

Stroke mimic: Perfusion magnetic resonance imaging of a patient with ictal paralysis.

We present an uncommon case of clinically diagnosed window period stroke subsequently recognised on diffusion - perfusion MRI as ictal paralysis due to focal inhibitory seizures or negative motor seizures. This case highlights the importance of MRI with perfusion imaging in establishing the diagnosis of stroke mimics and avoiding unnecessary thrombolysis.

Magnetic resonance imaging in cerebral malaria: a report of four cases.

OBJECTIVES: This is a retrospective institutional review of clinical data and radiological findings of cerebral malaria patients presenting to a tertiary centre in India, which is an known to be endemic for malarial disease. METHODS: The present series describes MRI in four cases all of which revealed bithalamic infarctions with or without haemorrhages in patients with cerebral malaria, and this review examines a subset of patients with this condition. In addition, acute haemorrhagic infarctions were also seen the in brain stem, cerebellum, cerebral white matter and insular cortex in two of the four patients. RESULTS: In this series, the patient with cerebellum and brain stem involvement died. The remaining three survived with antimalarial and supportive treatment. No neurological symptoms were noted on clinical follow-up. MRI follow-up was obtained in only one of the three patients (3 months post-treatment) and showed resolution of thalamic infarctions. CONCLUSION: These imaging features may help in the early diagnosis of cerebral malaria so that early treatment can begin and improve the clinical outcome.

Magnetic resonance imaging: current and emerging applications in the study of the central nervous system.

Neuroimaging is presently utilised in clinical practice for initial diagnosis and mapping of disease extent and distribution, noninvasive, preoperative grading of tumours, biopsy planning, surgery and radiation portal planning for tumors, judging response to therapy and finally, prognostication. Newer advances include magnetic resonance (MR) diffusion and diffusion tensor imaging with tractography, perfusion imaging, MR spectroscopy and functional imaging using the blood oxygen level-dependent contrast technique. Neuroimaging plays a pivotal role in various degenerative and neoplastic diseases, improving diagnostic accuracy, affecting patient care, monitoring dynamic changes within the brain during therapy, and establishing them as the arbiter of novel therapy that may one day prove cure of various brain diseases a reality.

Intradiploic frontal bone aneurysmal bone cyst in a child: a case report.

This report presents the imaging appearances of an uncommon case of intradiploic frontal bone aneurysmal bone cyst (ABC) in a 10-year-old girl. ABCs are rare in the calvarium. The radiological and aetiopathological differences between the more commonly occurring ABCs of the long bones and vertebrae, and their rarer counterparts in the calvarium and facial bones, have been discussed. Unique also to this case is the reconstruction performed using the outer table of the bone flap after excising the tumour.

Recent advances in imaging of brain tumors.

The recent advances in brain tumor imaging offer unique anatomical as well as pathophysiological information that provides new insights on brain tumors, directed at facilitating therapeutic decisions and providing information regarding prognosis. This information is presently utilized in clinical practice for initial diagnosis and noninvasive, preoperative grading of tumors, biopsy planning, surgery, and radiation portal planning, as well as, prognostication. The newer advances described in this review include magnetic resonance (MR) diffusion and diffusion tensor imaging with tractography, perfusion imaging, MR spectroscopy, and functional imaging, using the blood oxygenation level dependent (BOLD) technique. Diffusion tensor MR imaging is the only noninvasive in vivo method for mapping white matter fiber tract trajectories in the human brain. In the current clinical practice, one of the most important indications of diffusion tensor imaging (DTI) is to study the relation of a tumor to the adjacent white matter tracts. Perfusion imaging with computed tomography (CT) and magnetic resonance imaging (MRI) is an exciting new radiological technique for noninvasive evaluation of cerebral hemodynamics, in certain definite clinical settings. Cerebral perfusion imaging describes the passage of blood through the brain's vascular network. Perfusion imaging, especially with MRI has become an integral component of the complete radiological assessment of brain tumors. MR Spectroscopy (MSR) is the only noninvasive technique capable of measuring chemicals within the body. MRS distinguishes various metabolites on the basis of their slightly different chemical shifts or resonance frequencies. Functional MRI refers to the demonstration of brain function with neuroanatomic localization on a real-time basis. In patient care, functional MR imaging is primarily used in the preoperative evaluation of the relationship of a brain tumor with an eloquent cortex. The next decade will witness further sophistication of these techniques, with data available from larger studies. It is expected that imaging will continue to provide new and unique insights in neuro-oncology, which should hopefully contribute to the better management of patients with brain tumors.

Choroidal metastasis from non-seminomatous germ cell tumour of the testis.

Ureal metastases (although an uncommon site of metastatic involvement) are seen with primary tumours of the lung and breast and, very rarely, in other primary tumours. Undescended testis predisposes to malignancy. We present a rare case of choroidal metastasis from a non-seminomatous germ cell tumour arising in an undescended testis, and describe its clinical, ultrasound and MRI findings together with a relevant review of the literature.

Giant-cell tumour of the synovium in a facet joint in the thoracic spine of a child.

Giant-cell tumour of the synovium is known to affect the fingers or toes of adults. It has seldom been described in the spine and rarely in the thoracic vertebrae or in a child. The lesions of giant-cell tumour of the synovium have a classical radiological appearance, but require a high index of suspicion for correct recognition. Unlike giant-cell tumour of the synovium at other well-known sites, spinal lesions lack the characteristic papillary architecture, thereby raising other diagnostic possibilities. We describe a giant-cell tumour of the synovium of the left facet joint of a thoracic vertebra in a nine-year-old girl. The tumour was treated successfully by surgical excision.

Diffuse-type giant cell tumor of the subcutaneous thigh.

Diffuse-type giant cell tumor is an extra-articular form of pigmented villonodular synovitis. The localized form of this lesion (tenosynovial giant cell tumor) is frequent, representing the most common subset arising from the synovium of a joint, bursa or tendon sheath, with 85% of cases occurring in the fingers. The less frequent diffuse-type giant cell tumors are commonly located in the periarticular soft tissues, but on rare occasions these lesions can be purely intramuscular or subcutaneous We report the case of a 26-year-old female with diffuse-type giant cell tumor of the subcutaneous thigh, remote from a joint, bursa or tendon sheath. A review of the literature did not reveal any similar description of a diffuse-type giant cell tumor completely within the subcutaneous thigh, remote from a joint, bursa or tendon sheath. These lesions were initially regarded as inflammatory or reactive processes, but since the identification of clonal abnormalities in these patients, and in view of their capacity for autonomous growth, they are now widely considered to represent benign neoplasms.

Bilateral persistent hyperplastic primary vitreous.

We report a case of bilateral persistent hyperplastic primary vitreous (PHPV) in a 5-month-old infant who presented with bilateral leukokoria. The child was referred for ocular ultrasound with a clinical suspicion of retinoblastoma. Grey-scale evaluation revealed an echogenic band in the posterior segment of the left globe extending from the posterior surface of the lens capsule to the optic disc. Doppler examination revealed the presence of blood flow in the band. Ultrasound assessment of the contralateral globe showed an elevated mass of echogenic tissue in the posterior segment, in contact with the optic disc. Most cases of PHPV are sporadic and unilateral. Bilateral PHPV is rare. In a study by Pollard of 83 cases, only two patients (2.4%) had bilateral PHPV. The imaging features in this case point toward the diagnosis of bilateral PHPV. We suggest that this entity, although rare, should be considered in the differential diagnosis while evaluating bilateral leukokoria.

Primary rhabdomyosarcoma of the seminal vesicle.

Sarcomas of the seminal vesicle are very rare and poorly documented; as it is not always possible to pinpoint a truly vesicular origin of the pelvic mass due to local spread at the time of presentation. The purpose of the article is to document and characterize a rhabdomyosarcoma of the seminal vesicle of which to the knowledge of the authors there has been no previous report in the English literature.