Retrolaminar chiasmal migration of intraocular silicone oil masquerading as subarachnoid hemorrhage on CT head.

Silicone oil is used as a long-term treatment agent for intraocular tamponade to repair retinal detachments following vitrectomy. Retrolaminar migration of oil into the optic nerve is a rare complication, with migration into the optic chiasm being even more rare. Following imaging, this entity can be misdiagnosed as acute hemorrhage, aneurysm, or neoplasm on imaging possibly leading to delay of care or unnecessary interventions. We will discuss a case where the imaging findings were thought to represent a small acute subarachnoid hemorrhage possibly related to an aneurysm involving the distal right internal carotid artery.

MRI spot sign: Gadolinium contrast extravasation in an expanding intracerebral hematoma on MRI.

We report a rare case of gadolinium contrast extravasation in a rapidly expanding basal ganglia hemorrhage on magnetic resonance imaging (MRI). Contrast extravasation within an intracerebral hematoma (ICH) on computed tomography (CT) angiography has been described as the "spot sign" and is a well-known indicator of active bleeding; however, contrast extravasation has seldom been reported on MRI. In this case, a 61-year-old female inpatient developed acute left hemiparesis and dysarthria on her third day of hospital admission. An initial noncontrast head CT showed an ICH, increasing in size on the follow-up CT study, and a subsequent MRI brain without and with contrast demonstrated multiple round collections of active bleeding at the margins of the hematoma on the postcontrast images. A CT angiogram performed following the MRI confirmed contrast extravasation along the margins of the hematoma. This case is unique as it demonstrates the "spot sign" with MRI, and the multiple foci of active bleeding identified with MRI support the "avalanche" hypothesis, which proposes that the initial expanding ICH leads to additional arterial ruptures and propagation of bleeding.

Peritoneal Mouse as Detected on (18)F-FDG PET-CT.

We present the case of a 77-year-old male with a history of prostate cancer. Follow up PET-CT and contrast-enhanced CT demonstrated a small peritoneal loose body or "mouse" in the pelvis. This is an uncommon, benign, asymptomatic finding which is usually incidentally discovered. The significance of being aware of this entity is to distinguish it from metastasis, especially in patients with known abdominal and pelvic malignancies.