Perfusion Explained

Dynamic susceptibility contrast perfusion imaging:
-rapid injection of MR contrast agent
-intravascular T2 relaxation with signal loss
-dynamic time-signal cure on each pixel
Three major perfusion parameters:
-negative enhancement integral = cerebral blood flow (CBV)
-mean time to enhance (MTT)
-blood flow CBV/MTT
Perfusion imaging:
-differentiate ischaemic stroke from haemorrhagic stroke
-more sensitive than diffusion imaging
-candidates for anti-coagulant therapy detected earlier
-determines the salvagable brain tissue
-reduces the susceptibility of brain to further ischaemic damage

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Coccygodynia

Common causes: anorectal infection, chronic trauma involving poor sitting posture, acute trauma, and parturition.
The pain originates in spasm of the levator ani and coccygeus (and at times in the mesial fibers of the gluteus maximus) muscles.
X-ray examination is of diagnostic value only in cases of suspected fracture or dislocation. MRI is the investigation of choice.
Relief obtained by injections of alcohol, or of various anesthetic agents, with or without cortisone.
Treatment by properly applied massage of the levator ani and coccygeus muscles, and at times of the mesial fibers of the gluteus maximus muscle gives relief.

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Pontine Glioma

Brainstem gliomas occur at 3 distinct anatomic locations—diffuse intrinsic pontine, tectal, and cervicomedullary. Intrinsic pontine gliomas carry a grave prognosis. Brainstem gliomas have been reported to make up 2.4% of all intracranial tumors in adults and 9.4% of intracranial tumors in children.Morbidity is due to the location of the space-occupying lesion and compression of surrounding structures; because these structures regulate basic body functions of blood pressure, respiration, and swallowing as well as motor and sensory functions, compression can produce substantial neurological disability. Bimodal age distribution has been noted, with a peak incidence in the latter half of the first decade of life and a second peak in the fourth decadeThe typical MRI appearance of a brainstem glioma is an expansile, infiltrative process with low-to-normal signal intensity on T1-weighted images and heterogeneous high-signal intensity on T2-weighted images, with or without contrast enhancement.

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Fluid Levels in Medical Imaging

Radiologists must be familiar with the appearances and significance of fluid levels. It is important to appreciate that only images in the vertical plane will show this phenomenon.On radiographs the common fluid levels : chest (achalasia, hiatus hernia, hydropneumothorax or cavitating lesion), abdomen (intestinal obstuction) and truama (lipohaemarthrosis in knee and paranasal sinuses in facial fractures).CT with its high inherent contrast between gas, fat and fluid is an excellent technique for the demonstration of fluid levels in abdomen, chest and in extremity truama. MRI adds greater inherent contrast for different types of liquids and is used to demonstrate layering in lipohaemarthrosis, staging bone and soft tissue tumours, aneurysmal bone cyst, giant cell tumour and synovial sarcoma. Although ultrasound is the most difficult imaging technique to reliably demonstrate fluid levels it can be used to show levels due to seperation of blood withing a false aneurysm.

To read more: Clinical Radiology December 2007

Lead Poisoning

The salient manifestations of lead poisoning:
1.Dense metaphyseal lines
2.Lead encephhalopathy:
Acute – cerebral oedema & microhaemorrhages
Chronic – patchy calcifications, atrophy & white matter changes
3.Sutural widening
4.Hepatospleenomegaly
5.Abdominal radiographs may show lead containing objects in GIT

Multicentric Carcinoma Breast

Clinical Issues:
Multicentric in 10% of cases
Second focus may be microinvasive
Axillary positivity is 52%
Directly proportionate to tumour volume
Evaluation of each lesion necessary

Cerebral Venous Thrombosis

Cerebral venous thrombosis is a rare condition affecting predominantly adolescents or young adults. The presentation is often non-specific, and delay in diagnosis is common.This case draws attention to the multi-causal nature of cerebral venous thrombosis in young adults, and highlights the issue of masked mastoiditis. A coordinated approach by otolaryngological and haematological teams is recommended in such cases.