Cone beam CT: non-dental applications.

Initially cone beam CT was almost exclusively used to perform dental radiology. However, the first generation CBCT systems were later increasingly used to study sinuses, facial and nose fractures, temporomandibular joints etc. 3D-cephalometric head and neck studies became possible once CBCT systems were available that allowed scanning of the complete head. For this purpose a double rotation technique with stitching of the resulting two data sets was needed. CBCT systems on which the rotation could be stopped were needed to perform dynamic swallow or pharyngography studies. The advent of more powerful high-end CBCT systems led the way to temporal bone and skull base imaging. Finally, high-end "supine" CBCT systems using a "gantry" made small joint musculoskeletal imaging possible. These non-dental CBCT studies gradually replaced conventional X-rays and CT/MDCT studies because they allowed imaging with higher resolution, lower radiation dose and less metal artifacts. In this paper the most important non-dental CBCT indications will be discussed.

[Sudden onset vertigo: imaging work-up]. / Exploration radiologique d'un vertige aigu.

Vertigo and dysequilibrium are a frequent cause of medical consultation. Clinical evaluation is essential. Some cases of vertigo are diagnosed clinically while others require imaging, sometimes emergently (suspected stroke). MRI is the imaging modality of choice to assess the labyrinth (labyrinthitis? labyrinthine hemorrhage?), internal auditory canal (vestibular schwannoma? other tumor?…) and brain parenchyma including all structures of the auditory pathways: vestibular nuclei, vestibulocerebellar tract, tracts involved with ocular motricity, vestibular cortex… Multiple central etiologies exist: stroke, multiple sclerosis, tumor… However, some etiologies are best depicted with CT, especially lesions of the labyrinth: cholesteatoma, trauma, suspected dehiscence of the superior semicircular canal, suspected labyrinthine fistula… Finally, imaging may be negative (Benign Paroxysmal Positional Vertigo, Meniere's disease, vestibular neuritis, migraine…), merely reducing the differential diagnosis.

Imaging of intralabyrinthine schwannomas: a retrospective study of 52 cases with emphasis on lesion growth.

BACKGROUND AND PURPOSE: Only a few case reports and small series of intralabyrinthine schwannomas (ILSs) have been reported. The purpose of this study was to assess prevalence, MR characteristics, location, clinical management, and growth potential/patterns of ILSs in the largest series reported. MATERIALS AND METHODS: Lesion localization, MR characteristics, lesion growth, and clinical management were reviewed in 52 patients diagnosed with an ILS between February 1991 and August 2007 in 2 referral centers. The number of ILSs and vestibulocochlear schwannomas in the cerebellopontine angle/internal auditory canal was compared to assess the prevalence. RESULTS: ILSs most frequently originate intracochlearly, are hyperintense on unenhanced T1-weighted images, enhance strongly after gadolinium administration, and are sharply circumscribed and hypointense on thin heavily T2-weighted 3D images. The scala tympani is more frequently or more extensively involved than the scala vestibuli. Follow-up MR imaging, available in 27 patients, showed growth in 59% of subjects. Growth was seen from the scala tympani into the scala vestibuli and from the scala vestibuli to the saccule and vice versa. Twelve lesions were resected, and the diagnosis of ILS histopathologically confirmed. CONCLUSION: ILSs can account for up to 10% of all vestibulocochlear schwannomas in centers specializing in temporal bone imaging, grow in more than 50%, and are most frequently found intracochlearly, often anteriorly between the basal and second turn. Cochlear ILSs most often originate in the scala tympani and only later grow into the scala vestibuli. Growth can occur from the cochlea into the vestibule or vice versa through the anatomic open connection between the perilymphatic spaces in the scala vestibuli and around the saccule.

Splenic hamartoma presenting as an occasional asymptomatic finding.

We report a case of splenic hamartoma that was occasionally detected. Ultrasonography performed as a screening examination revealed a hypoechoic splenic lesion. A computed tomography and magnetic resonance examination were performed in order to characterize the lesion but failed to make a final diagnosis. An elective laparoscopic splenectomy with consecutive histologic examination revealed a splenic hamartoma. Splenectomy may be required for definite characterization of this type of splenic lesion.

Improved focal liver lesion detection: comparison of single-shot diffusion-weighted echoplanar and single-shot T2 weighted turbo spin echo techniques.

The purpose of this study was to compare diffusion-weighted respiratory-triggered single-shot spin echo echoplanar imaging (SS SE-EPI) sequence using four b-values (b = 0, b = 20, b = 300, b = 800 s mm(-2)) and single-shot T2 weighted turbo spin echo (T2W SS TSE) in patients with focal liver lesions, with special interest in small (<10 mm) lesions. Twenty-four patients underwent routine MRI. The five sequences were compared qualitatively for image quality, lesion conspicuity and artefacts. Quantitative analysis was performed for lesion identification and lesion-to-liver contrast-to-noise ratio (CNR). Subgroup analyses were performed for different types of lesions with different sizes. Sequences were compared by rank order statistic (RIDIT) and Kruskal-Wallis test. The best image quality (p<0.05) was achieved with T2W TSE and the best lesion conspicuity (p<0.05) with T2W TSE for biliary cysts and SE-EPI diffusion-weighted imaging (DWI) (b = 20 s mm(-2)) for haemangiomas and metastases. Image artefacts were lowest (p<0.05) with T2W TSE. T2W TSE was found to be the best protocol (p<0.05) for the identification of biliary cysts and SE-EPI DWI (b = 20 s mm(-2)) for haemangiomas and metastases. The lesion-to-liver CNRs were highest on T2W TSE for biliary cysts and on SE-EPI diffusion-weighted imaging (DWI) for haemangiomas and metastases (p<0.05). This study shows the potential of SS SE-EPI DWI (especially with a b-value of 20 s mm(-2)) as a promising technique for detecting small (<10 mm) focal liver lesions.

Aortopulmonary artery fistula in atherosclerotic pseudoaneurysm presenting with congestive heart failure after aortic valve replacement.

An exceptional case of a giant pseudoaneurysm of the atherosclerotic ascending aorta complicated by aortopulmonary fistulization twelve years after aortic valve replacement is presented. The patient underwent successful surgical repair. In patients with a marked atherosclerotic thoracic aorta presenting with congestive heart failure and an acquired continuous systolo-diastolic murmur, aortopulmonary fistula should be considered and differentiated from ruptured sinus of valsalva aneurysm. Multi-slice computed tomography was the most useful diagnostic tool in planning surgical strategy and approach. Surgery is the treatment of choice for this serious albeit rare entity.

External iliac artery fibrodysplasia.

We report a patient in the "atherosclerotic age" with symptomatic fibromuscular hyperplasia of both external iliac arteries. Our patient had a history of bilateral intermittent claudication secondary to a concentric narrowing of a long segment of both external iliac arteries. A typical associated involvement of both internal carotid arteries was present.

Lyme disease in childhood presenting as primary leptomeningeal enhancement without parenchymal findings on MR.

We report the MR appearance of a rare case of Lyme disease presenting as diffuse leptomeningeal enhancement in the absence of parenchymal lesions. In the appropriate clinical setting, one should consider Lyme disease in the differential diagnosis of meningeal enhancement.

Chronic focal fibrosing pancreatitis: detection by MRI.

The study of a 70-year-old woman with fibrosing pancreatitis, an uncommon variety of chronic pancreatitis, presenting as a discrete solid mass in the head of the pancreas, is reported. CT and US were non-diagnostic while ERCP and MR detected a focal anomaly. This case report stresses the sensitivity of MR in some pancreatic pathologies.