Nuclear medicine and ultrasound in the evaluation of neurologic diseases.

Echoencephalography and radionuclide brain imaging are used to aid in the diagnosis of a variety of intracranial abnormalities. Because of technical considerations, A-mode rather than B-mode echography must, under most circumstances, be employed for examination of the head. There are technical limitations to echoencephalography, and it tends to be relatively subjective and dependent on the skill of the sonographer. These factors have, to some extent, been responsible for the more limited application of ultrasound to neurologic diagnosis, as compared to the application of radionuclides. The most common use of echoencephalography is in the detection of midline shifts associated with various sequelae of head trauma. Ultrasound has also been used to detect space-occupying lesions, either directly or more usually by determing associated midline displacements. The characterization and follow-up of known lesions with ultrasound has also been described. In the above instances its usefulness is usually as a noninvasive technique complementary to nuclear medicine studies, which under most circumstances are more effective than ultrasound. The evaluation of ventricular enlargement, which is not usually possible per se with radionuclides, is possible with ultrasound. Computerized transverse tomography (CTT) can be applied more efficiently in a routine way in many of the above circumstances, including evaluation of ventricular size. The combination of CTT and nuclear medicine procedures in the brain area is so effective and comprehensive that where these are both available the demand for ultrasound will probably decrease but will not be eliminated.

Rapid diagnostic imaging of acute, nonclassic appendicitis by leukoscintigraphy with sulesomab, a technetium 99m-labeled antigranulocyte antibody Fab' fragment. LeukoScan Appendicitis Clinical Trial Group.

BACKGROUND: The purpose of this study was to evaluate the safety and efficacy of a technetium 99m-labeled antigranulocyte antibody Fab' fragment (sulesomab) as a diagnostic imaging agent in patients with suspected acute, nonclassic appendicitis. METHODS: This prospective multicenter trial involved 141 children and adults with suspected acute, nonclassic appendicitis. The investigators interpreted planar images acquired 15 to 30 minutes and 1, 2, and 4 hours after injection and also by single-photon emission computed tomography (SPECT). The imaging results were confirmed surgically, whereas nonsurgical patients were considered as not having appendicitis (intent to treat). RESULTS: Sulesomab had a sensitivity of 91% (29/32 patients) and a negative predictive rate of 97% for acute appendicitis. It detected additional abnormalities in 7 of 9 patients with other inflammatory abdominal disease and had a specificity of 92% (91/99 patients) and a positive predictive value of 80% for surgically confirmed right-lower-quadrant disease. In positive studies, 26% were identified by planar imaging at 15 to 30 minutes, 46% by 1 hour, 63% by 2 hours, and 71% by 4 hours; 29% required SPECT to detect the abnormality. Scanning time was 5 to 10 minutes per planar image and about 45 minutes for a SPECT study. Investigators found that sulesomab would have changed clinical management or reduced additional diagnostic studies in 64% of the patients. Adverse events were infrequent, minor, and self-limiting (9/141 patients, 6%). No human antimurine antibody response occurred in 48 evaluable patients. CONCLUSIONS: Sulesomab is safe, well-tolerated, and with no apparent immunogenicity. Focal inflammation or infection in the setting of suspected atypical appendicitis is rapidly and accurately detected. Management decisions incorporating sulesomab imaging potentially provide clear patient benefits, especially by correctly predicting surgery to be unnecessary in 97% of patients without acute appendicitis.

Sacrococcygeal teratoma.

Two cases of sacrococcygeal teratomas are presented. One case illustrates the long course of urologic problems produced by a "successful" removal of the tumor. The literature is reviewed, and the characteristics of this congenital tumor are discussed.

Value of scrotal scanning. Report of 62 cases.

A review of sixty-two technetium scrotal scans performed over a one-year period has led to a classification of pathologic states based on the degree of uptake of the radioactive isotope. Absent uptake, or a "cold" scan, is present only with testicular torsion, and rarely with avascular tumors. Increased uptake, or a "hot" scan, is most commonly seen with inflammatory conditions such as acute epididymitis and orchitis, and less commonly with tumor. "Mixed" scans can be associated with abscess, tumor with necrosis, trauma, and late torsion.

A comparative study of peripheral to central circulation delivery times between intraosseous and intravenous injection using a radionuclide technique in normovolemic and hypovolemic canines.

Intraosseous infusion is considered a useful technique for administration of medications and fluids in emergency situations when peripheral intravascular access is unobtainable. This study examined the effectiveness of intraosseous infusion for delivery of substances to the central circulation. Central deliveries of a radionuclide tracer administered by the intraosseous and intravenous routes were evaluated during normovolemic and hypovolemic states. Intraosseous infusion achieved peripheral to central circulation transit times comparable to those achieved by the intravenous route. Analysis of variance revealed no statistically significant differences between the peripheral to central delivery times comparing intraosseous and intravenous administration. The results demonstrate that intraosseous infusion is a rapid and effective method of delivery to the central circulation and is an alternative method for intravascular access. This study also suggests that a radionuclide tracer is useful for the evaluation of transit times following intraosseous injection.

Liver/pleural cavity scan for diagnosis of subphrenic abscess.

The interpretation of a combined liver/lung scan can be difficult in patients with pleural or pulmonary disease. A procedure is suggested to circumvent these difficulties by injecting 99mTc-sulfur colloid into the pleural cavity. A scan of the pleural cavity can then replace the lung scan in the conventional liver/lung scan. Two examples of liver/pleural cavity scans are shown.

Managing the solitary thyroid nodule: echography's role.

Improved preoperative thyroid diagnosis and reduction of needless thyroid surgery are achieved by employing gray scale echography in patients whose solitary thyroid nodule is cold on scintillation scanning. It is highly useful in distinguishing solid tissue from a cyst, identifying degenerative changes, guiding needle biopsy, and monitoring changes in a nodule during suppressive therapy.

Contrast enhanced CT scan and radionuclide brain scan in supratentorial gliomas.

The preoperative contrast enhanced CT and radionuclide brain scans of 60 patients with surgically verified supratentorial astrocytomas were evaluated and compared. Results indicated that the mechanisms of contrast enhancement and radionuclide uptake are identical in the detection of supratentorial gliomas. These diagnostic methods apparently mirror the integrity of the blood-brain barrier and therefore can be useful in assessing the degree of malignancy of supratentorial gliomas. However, lesions with an intact blood-brain barrier will be missed with radionuclide imaging. These parenchymal abnormalities and/or the associated mass effect will be detected with contrast enhanced computed tomography. These findings firmly establish contrast enhanced computed tomography. These findings firmly establish contrast enhanced CT as the primary investigate tool in the suspected brain tumor.

Thyroid echography of subacute thyroiditis.

Ultrasound was used to study 10 patients with subacute thyroiditis. With gray-scale technique, a "washed-out" appearance was seen during the active phase of the active phase of the illness. Clinical migration of the inflammation was accompanied by migration of the sonographic abnormality. Ultrasound can be especially helpful in the diagnosis of unilateral subacute thyroiditis and the differentiation of true cysts from hemorrhagic degeneration of goiter.

A spectrum of diseases of the thyroid gland as imaged by gray scale water bath sonography.

A method of performing gray scale thyroid echography with a 3.5 MHz focused transducer and an open water bath is described. A preliminary echographic classification of abnormalities and representative echograms illustrating various thyroid disorders are presented.

The contrast-enhanced CT scan and the radionuclide brain scan: parallel mechanisms of action in the detection of supratentorial astrocytomas.

The preoperative contrast-enhanced CT scan and the radionuclide brain scan of 70 patients with surgically verified supratentorial astrocytomas were evaluated and compared. The results indicate parallel mechanisms of action of contrast enhancement and radionuclide uptake. These diagnostic modalities apparently mirror the integrity of the blood-brain barrier (BBB) and therefore are useful in assessing the degree of malignancy of supratentorial gliomas. However, lesions with an intact BBB will be missed with RN imaging. These lesions and/or the associated mass effect will be detected with contrast-enhanced computed tomography. Our findings firmly establish contrast-enhanced CT as the primary investigate tool in the suspected brain tumor.

Cd1-xZnx Te Detectors for Digital X-Ray Chest Imaging.

Radiographic studies with the aim of optimizing the imaging potential of Cd1-xZnxTe detectors for digital chest radiography have been performed. A geometrical chest phantom has been designed, and the dependence of both the signal-to-noise ratio and contrast resolution of a planar Cd1-xZnxTe detector on the phantom thickness has been experimentally determined. Specifically, the detected signal and noise contributions were measured and related to phantom thickness. The results of this study indicate that Cd1-xZnxTe detectors exhibit both high signal-to-noise ratio and contrast resolution. At present time, several studies are in process to experimentally identify and quantify the imaging potential of Cd1-xZnxTe detectors for digital radiographic applications.

A comparison of radionuclide scanning and computed tomography in metastatic lesions of the brain.

Forty-seven patients with a final diagnosis of brain metastases were studied with both computed tomography (CT) and radionuclide (RN) scanning. Fifty-three percent of these patients also underwent contrast enhanced CT. Radionuclide scanning detected 94% of the cases, while CT without contrast enhancement was positive in 89%. The addition of contrast material to the CT examination increased the total sensitivity of CT to 94% and permitted the detection of two cases that were falsely negative on RN scanning and CT without contrast. With both techniques, lesions in the cerebral hemispheres were detected more readily than infratentorial lesions. Radionuclide scanning was less sensitive than CT without contrast in the detection of multiple metastases. Contrast enhanced CT should be used in all cases of suspected cerebral metastases unless contraindicated.

Optimization of Cd1-xZnxTe Detectors for Digital Radiography.

In this study, measurements of the electrical and detection parameters of the Cd1-xZnxTe detectors, within the x-ray diagnostic energy range, have been performed with the aim of optimizing the image quality parameters of these solid-state-ionization detectors. Namely, the leakage current and system capacitance of the x-ray imaging system have been measured as they relate to signal parameters. Similarly, the detected signal and noise contributions were measured and related to the radiation exposure and tube current setting. Furthermore, the detector contrast has been experimentally determined. The experimental results indicate that Cd1-xZnxTe detectors have low leakage current, high resistivity, and high detector contrast resolution. Therefore, they appear to be very attractive for imaging applications with applications in x-ray digital radiography.

Signal Dependence on Irradiation Geometry of Cd1-xZnxTe Detectors for Digital X-Ray Imaging.

CdZnTe is one of the most promising semiconductor material in the field of digital X-ray imaging, and may be operated at room temperature. To improve the detector characteristics, ternary systems such as Cd1-xZnxTe were grown by the high pressure Bridgman (HPG) technique. The signal performance characteristics of quasi-resistive Cd1-xZnxTe semiconductor detectors, was studied at different directions of irradiation, within the X-ray diagnostic energy range. The experimental results suggest that the total efficiency of these semiconductor detectors depends upon the energy absorption efficiency as well as the charge collection efficiency. This imaging detector allows one to investigate methods to improve the detection and imaging performance parameters as part of the development of an X-ray imaging system.

Contrast Study of CdZnTe Detectors for Digital Mammography.

Experiments have been performed with the aim of optimizing the image quality parameters of CdZnTe detectors for digital mammography. A geometrical breast phantom has been designed, and the dependence of the contrast resolution of a planar CdZnTe detector on the phantom thickness has been experimentally determined. Specifically, the detected signal and noise contributions were measured and related to phantom thickness. The results of this study indicate that the CdZnTe detectors exhibit a high contrast resolution. On the other hand, the dynamic range of this detector can be improved significantly by further implementation of the data acquisition electronics.

Electric Field Dependence on Charge Collection of CdZnTe X-Ray Detectors.

In this study, the electric field dependence on the charge collection process of CdZnTe detectors, at different x-ray tube settings, within the x-ray diagnostic energy range, is investigated. In addition, the detector contrast at different applied bias voltages and x-ray tube settings have been experimentally determined. The experimental results suggest that an efficient charge collection process is obtained by increasing the applied bias voltage. Once the applied bias voltage is sufficiently high, charge collection becomes complete and the detector operates in the saturation region. This is a prerequisite for high contrast and spatial resolution. As a result, the detector contrast is enhanced significantly. Therefore, CdZnTe detectors appear to be potential candidates for digital radiographic applications.