A. Eric Jones

Tissue Signatures with Dual-Energy Computed Tomography

By providing information on two parameters, dual-energy computed tomography can offer clinically useful tissue signatures for metallic deposits (Ca) or injected iodine, as well as for different normal and abnormal types of brain parenchymal tissues and CSF. Cerebral CT was performed on 36 patients and tissue differences analyzed using Hounsfield notation.

Radionuclide scanning and microangiography of evolving an completed brain infarction A correlative study in monkeys

A correlative study between sequential radionuclide brain scanning and time-lapse microangiograms has been carried out in an experimental model of ischemic cerebral infarct in monkeys. In the majority of animals, brain scintigraphy became positive by two weeks, then regressed toward negative by four to six weeks after ligation of the middle cerebral artery. Increased radioisotope uptake is clearly related to neovascularization around the area of infarct as shown by the microangiograms. At later stages, decreased vascularity, peripheral gliosis, and central cavity formation are the main factors determining diminution of radionuclide penetration in the involved area.

Assessment of regional left ventricular function by sector analysis: A method for objective evaluation of radionuclide blood pool studies

Regional wall motion abnormalities are most often detected visually, and hence subjectively, in gated blood pool studies of the heart. Therefore, an automated method was developed to objectively assess regional left ventricular (LV) function. The method was tested in 26 normal volunteers and 29 patients with angiographically proved coronary artery disease. Fifteen patients with coronary artery disease had a normal LV ejection fraction (EF) at rest, and all had an abnormal EF response with exercise; 23 had visual regional wall motion abnormalities with rest or exercise. The left ventricle was divided into 28 sectors that radiated from the LV center of gravity, with 1 region at the LV center. A time-activity curve was generated for each sector and the EF and Fourier phase were computed from each curve. Rest and exercise sector EF versus sector number plots were superimposed and the area difference between these 2 curves was taken as an index of regional contraction. Similarly, an estimator of sector phase differences, obtained from the plot of phase versus sector number, was taken as an index of wall motion asynchrony. Analysis of the reliability of these 2 indexes suggests that this automated technique has at least the same efficiency as subjective evaluation of gated blood pool studies, but possesses the advantage of objectivity. The technique may also be useful in localizing regional defects and, perhaps, in detecting mild abnormalities not readily perceived visually.

67Ga-Citrate Scintigraphy of Brain Tumors

67Ga localization by brain tumors was seen in 19 of 21 patients with known brain tumors. Two negative studies were obtained from patients with slowly-growing tumors. Approximately 1/3 of the tumors were imaged more clearly with 67Ga than with 99mTc, but localization of both isotopes appeared to be related to the type of tumor, degree of malignancy, and previous therapy.

Radionuclide studies in Hodgkin's disease and lymphomas

A rational, multidisciplinary approach to Hodgkins disease and the non-Hodgkins lymphomas has been responsible for major advances in therapy. Invasive diagnostic procedures and exploratory laparotomy, with their associated complications, make nontraumatic radionuclide imaging most appealing in both the clinical staging of disease and in evaluating therapy. Gallium-67-citrate, the tumor scanning agent of the early 1970s, has demonstrated a marked affinity for Hodgkins disease and the other lymphomas. False positives are few, with sensitivity greater than 70% throughout the spectrum of Hodgkins disease and the histiocytic lymphomas. In addition to confirming sites of suspected neoplasm, this agent has proved useful in the detection of occult involvement. Moreover, resolution of abnormal gallium-67 concentrations on follow-up studies functions as a visual ancillary index of therapeutic response. The value of wholebody gallium-67 scintigraphy is further enhanced when used in conjunction with routine technetium brain, bone, liver, and spleen scans. While the diagnostic accuracy of gallium-67 studies has been limited in the abdomen due to bowel activity, our attempts to improve these results with the tumor-seeking radiopharmaceutical indium-111-Bleomycin were unrewarding and subsequently were discontinued. Finally, radionuclide lymphography has also been explored. Its diagnostic usefulness in detecting pelvic and abdominal lymph node involvement warrants further investigation.

Brain Scintigraphy with 99mTc Pertechnetate, 99mTc Polyphosphate, and 67Ga Citrate

Nineteen patients with known or suspected neoplasms of the skull and/or brain were studied with 99mTc pertechnetate, 99mTc polyphosphate, and 67Ga citrate. Lesions of the calvaria were detected most accurately with 99mTc polyphosphate. In some cranial lesions, 67Ga citrate localized within the core, 99mTc polyphosphate outlined the periphery, and 99mTc pertechnetate demonstrated the entire affected area. In postcraniotomy patients, the combination of 67Ga citrate and 99mTc polyphosphate provided a basis for distinguishing the surgical scar from a recurrent intracranial tumor. Purely intracerebral lesions were generally poorly localized with 99mTc polyphosphate.

The significance of urinary bladder displacement noted on whole-body 18F bone scintigraphy.

Whole-skeletal scintigraphy was employed in a large group of patients with malignant lesions. An unusual pelvic distribution of 18F was noted in 3 cases. The images were initially interpreted as showing a pelvic bony lesion; however, the placement of the urinary bladder was in question, since each patient was known to have a pelvic tumor. Examination of the urograms in each case showed that the suspected abnormality was a displaced bladder. The necessity of correlating the appropriate roentgenographic studies with the radionuclide images is emphasized.

Value and Limits of Radionuclide Angiography of the Spinal Cord

Radionuclide rapid flow studies of the various spinal segments have been carried out in over 40 patients affected by progressive myelopathy of obscure origin as well as in normal controls. After intravenous injection of a bolus of 99mTc-human serum albumin or plain 99mTc-pertechnetate, images were obtained with a gamma camera. Fourteen of twenty-one proved arteriovenous malformations and three (hemangiobalstomas) of seven verified tumors of the spinal cord have been detected by this method. Radionuclide angiography is a reliable, simple, and innocuous screening and follow-up test for most of arteriovenous malformations and some tumors of the spinal cord.