Blood supply to the human thalami is complex and multiple variants exist. The artery of Percheron is one of those variants and is characterized by a solitary arterial trunk that branches from one of the proximal segments of either posterior cerebral artery and supplies blood to the paramedian thalami. Its occlusion results in bilateral paramedian thalamic infarction sometimes extending to the midbrain. We report six cases of bithalamic infarction secondary to occlusion of the artery of Percheron. We will illustrate the complex clinical symptomatology and underscore the role of imaging, especially MRI, for diagnosis.

Tarsal tunnel syndrome is a condition that is caused by compression of the tibial nerve or its associated branches. Diagnosis is based on clinical findings but imaging is performed to exclude a cause of compression, identified in 60 to 80% of cases. Ultrasound is a useful examination because of its high spatial resolution and ability to rapidly perform an axial survey of the nerves. The ultrasound imaging features of the tarsal tunnel are described. The etiologies and different types are illustrated through a review of clinical cases.

Acute mesenteric ischemia (AMI) is a life-threatening emergency with prognosis directly correlated with the delay in diagnosis and treatment. Clinical and laboratory findings are nonspecific and it is imperative to look for findings of AMI on CT and ultrasound examinations performed in patients with acute abdomen. Arterial and venous ischemia are different entities with different clinical and imaging features, treatment and prognosis. The main causes of AMI are arterial thromboembolic disease and low-flow state. Venous ischemia is less frequent. Due to its high reported sensitivity (90%), CT should be performed as a firstline imaging modality when AMI is suspected. CT and ultrasound imaging features of AMI include: bowel wall thickness and enhancement abnormalities, pneumatosis, portal venous gas, demonstration of intravascular thrombus, bowel dilatation and ascitis.

Multiple artefacts and pitfalls may occur with breast MRI. Artefacts are secondary to the MR technique itself while pitfalls often are the result of human error. The most common artefacts include motion, pulsation, chemical shift and magnetic susceptibility. The most common pitfalls include improper contrast injection, poor patient positioning, improper placement of the ROI and improper characterization of physiological and iatrogenic contrast enhancement. The identification of these artefacts and pitfalls on breast MR images may reduce their impact or even eliminate them. The use of optimized protocols is necessary. It is important to explain to patients the sequence of the examination, ensure proper placement of the breasts in the coil and optimize the contrast injection. The ROI should always be placed over the most suspicious region of the lesion. Finally, it is recommended to perform the MRI during the second week of the menstrual cycle and to discontinue the use of HRT 2 months prior to scanning when possible.

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.