Journal De Radiologie最新文献

Infections of the head and neck are frequent and usually have a good prognosis even though complications may sometimes be life threatening. In addition to airway compromise, intracranial and thoracic extension may occur. Diagnosis usually is made on clinical examination and imaging may play a significant role in assessing the extent of the disease, detecting complications and assist in surgical planning. The imaging protocol should be appropriate for the proposed diagnosis and suspected complications. CT of the soft tissues of the neck and chest is the imaging test of choice. Interpretation requires knowledge of the anatomy to understand the modalities of local and distant spread of the disease. Imaging evaluation is important but should not delay emergently needed treatment for entities such as epiglottitis and necrotizing fasciitis.

Sinonasal and temporal bone infections may extend to the skull, skull base, meninges, pericerebral spaces, brain parenchyma, dural sinuses, deep cerebral or cortical veins, intracranial arteries and cranial nerves either via contiguous or hematogeneous spread. The site of infection dictates the sites of potential complications: orbital with ethmoid sinusitis, cavernous sinus thrombophlebitis and oculomotor palsies with sphenoid sinusitis, transverse sinus thrombophlebitis with mastoiditis and superior sagittal sinus thrombophlebitis with frontal sinusitis. All may result in brain abscess. Congenital and acquired defects of the skull and meninges, with or without associated meningocele or meningoencephalocele, perilymphatic fistulas, and some anomalies of the inner ear may predispose to the intracranial extension of ENT infections.

The clinical manifestations of vascular lesions of the head and neck may be variable (hemorrhagic, ischemic, compressive). Diagnosis often is made at the time of acute presentation, but delayed manifestations, sometimes long after the initial presentation, should not be overlooked. Hemorrhagic manifestations are characterized by epistaxis, corresponding mainly to lesions of the nasal cavities but involvement of the internal carotid artery should be excluded (life threatening). In addition, some vascular malformations may lead to severe hemorrhage. Ischemic manifestations typically result from arterial dissection. A venous origin is also possible. Carotid-cavernous fistulas rarely lead to hemorrhagic or ischemic manifestations and tend to result in ocular manifestations, typically delayed and sometimes misleading.

Sudden onset hearing loss is idiopathic. It occurs in less than 24 h and spontaneously resolves within 15 days in two thirds of cases. Imaging is performed to exclude other causes of sudden onset hearing loss (vestibular schwannoma, vertebral artery dissection, stroke) and evaluate the inner ear structures. A few anatomical anomalies have been associated with an increased risk of hearing loss. Morphological anomalies involved the following structures in decreasing order of frequency: lateral semicircular canal (hypoplasia and dilatation), superior semicircular canal, posterior semicircular canal, vestibule and cochlea. Enlargement of the vestibular aqueduct also is frequently observed.

The standard technique for brain activation functional MRI (fMRI) is the BOLD sequence. Two new techniques have emerged: arterial spin labeling (ASL) MRI and diffusion MRI. Both have the theoretical advantage of more accurately directly demonstrating neuronal activation compared to BOLD imaging, resulting in improved spatial and temporal resolution. ASL is a perfusion sequence using labeled arterial protons as an endogenous perfusion agent. In spite of methodological difficulties, quantitative CBF measurements are possible. ASL is less susceptible to venous contamination than BOLD and more reproducible. Diffusion MRI evaluates neuronal activation at the cellular level with the prospect of excellent spatial resolution. The main limitations for both techniques are the technical difficulties in the acquisition and the low SNR. AS such, ASL is not widely used clinically and diffusion remains in the field of research. However, the increasing availability of 3T MR systems coupled with multi-channel surface coils and improved postprocessing techniques should improve the detection of the brain activation signal. It is thus possible that these techniques could become clinically available either in complement to or as a replacement for BOLD imaging.

The number of patients with cochlear implant increases each year. Most of these patients may undergo MR imaging up to 1.5 Tesla, based on safety recommendations from each of the manufacturers. All external components should be removed for the examination. For three manufacturers providing about 85 % of all implanted devices in Europe, the internal components may be left in place and covered by an external bandage. Strict protocol guidelines must be implemented, especially head positioning in the magnet and within 30 cm from the bore opening. A single manufacturer, providing about 15 % of implanted devices, recommends surgical removal of the internal magnet prior to MR imaging.

Clinical evaluation of the nipple-areolar complex is a routine component of the breast screening examination. All persistent unilateral nipple lesion should be viewed with suspicion and Paget's disease of the nipple should be considered. The diagnosis is established by nipple scrape cytology. It is a rare variant of ductal carcinoma in situ. The breast imaging work-up should include a search for an underlying malignancy, present in over 80% of cases, not infrequently multifocal. Preoperative MRI is useful if breast conservative surgery is contemplated because of the high rate of occult malignancy on mammograms and ultrasound. Erosive adenomatosis of the nipple is a benign process that may simulate Paget's disease isolated to the nipple. Less frequently, pagetoid basal cell carcinoma, Bowen's disease and melanoma may be more difficult to differentiate clinically and share the unilateral and chronic features of Paget's disease. Biopsy is needed for diagnosis. Cutaneous extension of a breast cancer is rare but should be suspected in patients with retraction and/or fixed nipple. Eczema is characterized by the bilateral nature of the process, the absence of nipple deformity, the presence of flare-ups and the favorable response to local steroid therapy.