Evaluation of Single-Chip, Real-Time Tomographic Data Processing on FPGA SoC Devices.

A novel approach to tomographic data processing has been developed and evaluated using the Jagiellonian positron emission tomography scanner as an example. We propose a system in which there is no need for powerful, local to the scanner processing facility, capable to reconstruct images on the fly. Instead, we introduce a field programmable gate array system-on-chip platform connected directly to data streams coming from the scanner, which can perform event building, filtering, coincidence search, and region-of-response reconstruction by the programmable logic and visualization by the integrated processors. The platform significantly reduces data volume converting raw data to a list-mode representation, while generating visualization on the fly.

A model of unloaded human intervertebral disk based on NMR relaxation.

NMR relaxation rates were related to the composition of the nucleus pulposus from 11 and anulus fibrosus from six human intervertebral disks. Tissue water was proportional to glycosaminoglycan (GAG) and residue, the noncollagen, non-GAG portion of the dry weight (R2 = 0.74). The solid signal fraction depended on collagen and residue protons (R2 = 0.89). 1/T1 was proportional to collagen and residue (R2 = 0.97). T2 showed 2-4 components labeled A, B, C, and D, with means +/- standard deviations of 3.1 +/- 1.6, 17.5 +/- 9.5, 64 +/- 22, and 347 +/- 162 msec. Signal fractions of A and B depended on the collagen-associated water protons (R2 = 0.94 and 0.85), C on residue-associated water protons (R2 = 0.82), and D on GAG-associated water protons (R2 = 0.74). The data led to a model of disk architecture in which the collagen and residue were largely solid, forming distinct water compartments; the remaining water was present in a proteoglycan gel.

Acute abdomen: plain film utilization and analysis.

Abdominal radiographs are commonly requested indiscriminately for patients with abdominal pain, but the results of many such examinations are negative or non-specific. In today's era of high-technology studies, such as ultrasonography, computed tomography and magnetic resonance imaging, plain abdominal radiography is still appropriate in some situations, and the interpretation of abdominal plain films remains an essential and challenging component of most radiology practices. This article reviews a number of issues regarding the use of plain radiography: the common causes of abdominal pain in patients presenting to a typical emergency department; the appropriate indications for this type of examination so that the number of unnecessary examinations is minimized and the diagnostic yield thereby maximized; and the appropriate views to be obtained, the rationale for their use and a proposed format for standardized viewing of abdominal plain films. The article concludes with a practical review of some commonly misunderstood points regarding the bowel gas pattern and ascites.

Magnetic resonance imaging reflects the chemical changes of aging degeneration in the human intervertebral disk.

T2 weighed spin echo magnetic resonance images (MRI) of the intervertebral disks of 4 lumbar spines were graded and the nuclei pulposi were analyzed for water, collagen and proteoglycan. The brightness of the nuclear image correlated directly with the proteoglycan concentration, but not with the water or collagen. The dark midnuclear cleft had a collagen concentration slightly higher and a water concentration slightly lower than the adjacent zones; no corresponding differences in proteoglycan were seen, although the relationship with MRI grade was confirmed.

Hemangioma of the liver: characteristics exhibited on a 0.15 Tesla scanner.

Twenty-two liver hemangiomas, initially diagnosed using ultrasonography, were imaged with a Picker 0.15 Tesla super-conducting scanner in order to (1) determine the reliability of spin-echo (SE) signal intensity measurements and the calculated T1 and T2 values of both normal tissue and hemangiomas and (2) assess the characteristics of hemangiomas as visualized by a low-field magnetic resonance imaging unit. Reproducible measurements of T1 values and signal intensities are possible (r = 0.93-0.99) but T2 values are less reproducible (r = 0.79) and more variable. T1 values provide the best discrimination between hemangiomas and normal liver (99% successful classification) followed by the SE signal intensity differences (94%). Signal intensity ratios and contrast-to-noise ratios of lesions compared with liver are similar to those of other studies. Most small hemangiomas exhibit homogeneous signal intensity but larger lesions can be nonhomogeneous.

Subtle huge intervertebral disc herniation.

The accuracy of computerized tomography (CT) in diagnosing herniated discs has been well established. Huge herniated discs, which paradoxically may be very subtle, have been mentioned but not stressed as potential causes of false-negative diagnosis. Five cases during a 5-year period encompassing approximately 2500 examinations have been encountered by the authors. In this experience, the most consistent finding is the subtle increased density of the disc compared with the dural sac. The diagnosis is aided by awareness that huge discs severely compressing the dural sac may be very subtle; the use of narrower windows for CT scanning, sagittal re-formation, and occasionally the use of myelography with or without repeat CT scanning may also assist.

Choice of comparison group and findings of computerised tomography in schizophrenia.

The literature indicates that whether or not schizophrenic patients are reported to have significant lateral ventricular enlargement depends on control, and not schizophrenic-group values. This discrepancy does not result from differences in age, the ratio of males to females, the number of control subjects used in each study, or whether control groups are comprised of normal subjects or medical patients. However, medical-patient controls tend to have smaller ventricles than do normal individuals. Thus, we assessed lateral- and third-ventricle size and the degree of cortical atrophy in 30 normal volunteers, 30 medical patients, and 30 chronic schizophrenic patients. The use of a medical control group seemed to result in underestimates of ventricle and sulcal size in the normal population and, therefore, overestimates of these values in schizophrenic groups.

Ventricular and sulcal size at the onset of psychosis.

To determine whether abnormalities in brain morphology are present at the onset of illness, patients with schizophrenia, schizophreniform and bipolar disorders, and major depression who were experiencing their first episodes of psychosis were compared with normal and medical control subjects. The schizophrenic patients had larger third ventricles but not larger lateral ventricles or cortical sulci than the normal subjects. The other psychotic patients did not differ from the normal group on these measures. A different pattern of results emerged when the medical patients were used for comparison, indicating that the choice of control group can influence the findings of computerized tomography studies.

Magnetic resonance imaging of aneurysms of the abdominal aorta.

Experience with magnetic resonance imaging (MRI) of 10 normal control patients and 13 patients with known abdominal aortic aneurysms is presented. The aorta, renal artery origins, and iliac arteries were clearly identified in all control patients. Ten out of 13 aneurysms were optimally visualized. Three cases early in the experience were poorly seen and permitted less confident measurements. Renal artery origins were identified in 12 cases and judged to be uninvolved by the aneurysm in 11. Iliac arteries were identified in 11 cases and judged to be definitely aneurysmal in three. Sonography clearly depicted all 13 aneurysms. Correlation of the actual anteroposterior (AP) and transverse diameter aneurysm measurements with both techniques was excellent. Sonography failed to identify the renal artery origins in all cases, but could infer noninvolvement in two cases. Iliac arteries were seen in eight cases and judged definitely aneurysmal in three. According to these preliminary results, both MRI and sonography provide accurate AP and transverse outer wall measurements. MRI is superior in determining the presence of renal and/or iliac involvement. The authors recommend, however, that sonography continue to be the preliminary screening method.

Radiology of the Angelchik prosthesis for gastroesophageal reflux.

The placement of a ring prosthesis around the esophagus above the gastric cardia for treatment of gastroesophageal reflux has been shown to give acceptable clinical results and is technically easier than procedures such as gastropexy and fundoplication. Radiologists should be familiar with this surgical technique because postoperative follow-up and complications are best evaluated by radiologic imaging. The normal and abnormal radiologic features of the Angelchik antireflux device are described. Of 38 patients who underwent surgical implantation of the Angelchik prosthesis, four required postoperative removal of the device because of its dislodgment.