Intestinal ischemia, which refers to insufficient blood flow to the bowel, is a potentially catastrophic entity that may require emergent intervention or surgery in the acute setting. Although the clinical signs and symptoms of intestinal ischemia are nonspecific, CT findings can be highly suggestive in the correct clinical setting. In this chapter we review the CT diagnosis of arterial, venous, and non-occlusive intestinal ischemia. We discuss the vascular anatomy, pathophysiology of intestinal ischemia, CT techniques for optimal imaging, key and ancillary radiological findings, and differential diagnosis. In the setting of an acute abdomen, rapid evaluation is necessary to identify intraabdominal processes that require emergent surgical intervention (1). While a wide-range of intraabdominal diseases may be present from trauma to inflammation, one of the most feared disorders is mesenteric ischemia, also known as intestinal ischemia, which refers to insufficient blood flow to the bowel (2). Initial imaging evaluation for intestinal ischemia is typically obtained with CT. Close attention to technique and search for key radiologic features with relation to the CT technique is required. Accurate diagnosis depends on understanding the vascular anatomy, epidemiology, and pathophysiology of various forms of mesenteric ischemia and their corresponding radiological findings on MDCT. At imaging, not only is inspection of the bowel itself important, but evaluation of the mesenteric fat, vasculature, and surrounding peritoneal cavity also helps improves accuracy in the diagnosis of bowel ischemia.

Background and Purpose Deep brain stimulation of the thalamus has become a valuable treatment for medication-refractory essential tremor, but current targeting provides for only a limited ability to account for individual anatomic variability. We examined whether functional connectivity measurements between the motor cortex, superior cerebellum, and thalamus would allow discrimination of precise targets useful for image guidance of neurostimulator placement. Materials and Methods Resting BOLD images (8 minutes) were obtained in 58 healthy adolescent and adult volunteers. ROI’s were identified from an anatomic atlas and a finger movement task in each subject in the primary motor cortex and motor activation region of bilateral superior cerebellum. Correlation was measured in the time series of each thalamic voxel with the 4 seeds. An analogous procedure was performed on a single subject imaged for 10 hours to constrain time needed for single subject optimization of thalamic targets. Results Mean connectivity images from 58 subjects showed precisely localized targets within the expected location of the ventral intermediate nucleus of the thalamus, within a single voxel of currently used deep brain stimulation anatomic targets. These targets could be mapped with single voxel accuracy in a single subject with 3 hours of imaging time, although targets were reproduced in different locations for the individual than for the group averages. Conclusion Interindividual variability likely exists in optimal placement for thalamic deep brain stimulation targeting of the cerebellar thalamus for essential tremor. Individualized thalamic targets can be precisely estimated for image guidance with sufficient imaging time.

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AbstractBackgroundOver the past couple of decades, a number of centers in the brain have been identified as important sites of nociceptive processing and are collectively known as the ‘pain matrix.’ Imaging tools such as functional magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) have played roles in defining these pain-relevant, physiologically active brain regions. Similarly, certain segments of the spinal cord are likely more metabolically active in the setting of pain conditions, the location of which is dependent upon location of symptoms. However, little is known about the physiologic changes in the spinal cord in the context of pain. This study aimed to determine whether uptake of 18F-FDG in the spinal cord on positron emission tomography/computed tomography (PET/CT) of patients with low back pain (LBP) differs from that of patients without LBP.MethodsWe conducted a retrospective review of 18F-FDG PET/CT scans of 26 patients with non-central nervous system cancers, 13 of whom had reported LBP and 13 of whom were free of LBP (controls). No patients had spinal stenosis or significant 18F-FDG contribution of degenerative changes of the spine into the spinal canal. Circular regions of interests were drawn within the spinal canal on transaxial images, excluding bony or discal elements of the spine, and the maximum standardized uptake value (SUVmax) of every slice from spinal nerves C1 to S1 was obtained. SUVmax were normalized by subtracting the SUVmax of spinal nerve L5, as minimal neural tissue is present at this level. Normalized SUVmax of LBP patients were compared to those of LBP-free patients at each vertebral level.ResultsWe found the normalized SUVmax of patients with LBP to be significantly greater than those of control patients when jointly tested at spinal nerves of T7, T8, T9 and T10 (p < 0.001). No significant difference was found between the two groups at other levels of the spinal cord. Within the two groups, normalized SUVmax generally decreased cephalocaudally.ConclusionsPatients with LBP show increased uptake of 18F-FDG in the caudal aspect of the thoracic spinal cord, compared to patients without LBP.ImplicationsThis paper demonstrates the potential of 18F-FDG PET/CT as a biomarker of increased metabolic activity in the spinal cord related to LBP. As such, it could potentially aid in the treatment of LBP by localizing physiologically active spinal cord regions and guiding minimally invasive delivery of analgesics or stimulators to relevant levels of the spinal cord.

The one-day application of moxifloxacin resulted in significantly fewer positive conjunctival cultures, compared with a 1-h application.

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