The effect of intravesical pressure on glomerular filtration rate in patients with myelomeningocele.

Numerous investigators have demonstrated the development of hydronephrosis and renal deterioration in patients with myelomeningocele who have high pressure bladders. By drawing blood at sequential intervals during 99mtechnetium-diethylenetriaminepentaacetic acid renal scanning we are able to generate nuclide clearance curves that correlate well with glomerular filtration rate. Renal scanning is done most frequently with the bladder catheterized and left to gravity drainage. By filling the bladder under manometric control to a pressure of 35 to 40 cm. water we have followed routine scanning with continued blood sampling to generate nuclide clearance at low and high bladder pressures. In 5 myelomeningocele patients so studied we found consistent and significant decreases in glomerular filtration rate at high bladder pressures.

Predictors for weaning patients from ventricular assist devices.

In order to determine if hemodynamic parameters can accurately predict whether patients can be successfully weaned from ventricular assists devices (VADs), we studied 24 patients supported with Pierce-Donachy VADs (11 left VAD; 6 right VAD; 7 biventricular VAD) following cardiogenic shock for periods from 1.3 to 22 days (mean 5.4). Myocardial recovery was determined by daily measurements of "pump on/pump off" parameters, and the data from seven LVAD patients (64%) and three RVAD patients (50%) whose hearts recovered were compared to the data from those whose did not. Additionally, data from the five patients (71%) weaned from biventricular support were compared to those weaned from only a single LVAD or RVAD. In this study, daily pump on/pump off hemodynamic measurements were found to be predictive of success for weaning patients from VADs. The most significant predictors were increases in mixed venous oxygen saturation, cardiac index, mean arterial pressure and ventricular ejection fraction, as well as decreases in atrial pressures. Seventy percent of the patients weaned from VADs survived, indicating that patients appropriately weaned from VAD support have a reasonable chance of survival.

Experimental hemarthrosis in dogs: progressive synovitis monitored with technetium-99m pyrophosphate joint imaging.

We examined the time course of the development of hemorrhagic synovitis in response to repeated autologous blood injections into knee joints in mature dogs and the possible usefulness of joint imaging with technetium-99m pyrophosphate (Tc99m-PYP) in monitoring the early response of synovium to blood. Experimental hemarthrosis was induced in dogs by twice weekly injection of autologous blood into the knee joints. Sequential examination of the synovium at monthly intervals over a period of 12 weeks revealed early inflammatory cell infiltration and capillary neovascularization with eventual replacement of the normal fatty synovium by dense fibrous tissue. Serial Tc99m-PYP joint images demonstrated a progressive increase in isotope accumulation in the knees during the course of the study. Further isotope accumulation was observed after CO2 laser synovectomy. During the 24-week course of the entire study, no changes in joint cartilage or bone were observed by gross inspection or radiologic and light-microscopic examination. The findings indicate that the progressive proliferative, inflammatory, fibrotic changes in joint synovium associated with experimental hemarthrosis in dogs may be noninvasively and semiquantitatively assessed with the use of Tc99m-PYP scintigraphy. Evidence is also presented that the intensity of Tc99m-PYP joint accumulation (immediate static images) may not readily reflect synovial vascularity or synovial tissue mass.

Improved interpretation of exercise Tl-201 myocardial perfusion scintigraphy in women: characterization of breast attenuation artifacts.

Thallium-201 myocardial perfusion scintigraphy is reported to be a less accurate diagnostic test for coronary artery disease in women than in men. We retrospectively analyzed 34 Tl-201 studies obtained in 28 symptomatic women and compared them with those obtained in 32 men during the same interval. Three criteria were tested: criterion 1 was defined as abnormal scans showing any defect; criterion 2, scans showing only transient (reversible) defects; and criterion 3, scans showing either transient or "significant" (i.e., not due to breast attenuation) fixed defects. The sensitivity in women was 1.00, 0.73, and 0.93, respectively; the specificity, 0.26, 0.84, and 0.85. The best values in men were a sensitivity of 1.00 and a specificity of 0.86. The three criteria were then prospectively tested in 33 scans of 29 additional women. The sensitivity was 0.90, 0.65, and 0.80, respectively, and the specificity, 0.18, 1.00, and 0.92. Defects (usually fixed) due to breast attenuation artifact were seen frequently (30%). Criterion 3 best differentiates such defects from those resulting from coronary artery disease, making Tl-201 myocardial perfusion scintigraphy as accurate in women as in men.

Lymphoscintigraphy.

Lymphoscintigraphy is rapidly gaining favor as a noninvasive technique to assess lymphatic structure and function. The following essay summarizes the historical background and provides a synopsis of personal experience with radiolabeled (99mTc) human serum albumin (HSA) using this technique.

Misleading findings on indium-111 leukocyte images.

In-111 leukocyte imaging usually yields images which are interpreted easily. Five potentially misleading cases were noted, however, of over 200 scans performed over a four-year period. These included two cases of bladder visualization without bladder inflammation and three cases of abdominal activity without intra-abdominal abscess or inflammatory bowel disease. Migration of leukocytes from other true pathologic sites and technical factors were responsible for the activity seen. Knowledge of all aspects of the patient's clinical status, including other diagnostic modalities performed, was critical in arriving at the correct diagnosis.

Significance of diffuse cardiac activity on In-111 labeled leucocyte scans.

To assess the significance of diffuse cardiac activity (DCA) seen on In-111 labeled leukocyte scans, we reviewed 87 studies performed over the last 4 years. Inflammatory cardiac conditions were seen as frequently in patients with DCA (15%) as those without (7%, P = 0.3). There was a higher ratio of RBC:WBC in the final WBC preparation in the false-positive DCA group than the true positive DCA and no DCA groups. False-positive studies showing DCA are most likely due to residual blood pool activity.

Equilibrium radionuclide ventriculography in single ventricle.

With the recent advances in pediatric cardiology and cardiovascular surgery, assessment of ventricular function in single ventricle complexes is becoming increasingly important. The serial assessment of ventricular function helps our understanding of the natural and unnatural history in these patients. Equilibrium radionuclide ventriculography is safe, easy to perform, and well-suited to the serial assessment of ventricular function. Fifteen nuclear studies were performed in 15 children with single ventricle complex. Nuclear studies were imaged in both the anterior and left anterior oblique views in each patient. The ventricular ejection fraction calculated from the anterior view (the view with the best atrial-ventricular separation) closely approximated the cineangiographic ejection fraction (54.0 vs 59.1%). Equilibrium radionuclide ventriculography is a valid method to calculate ventricular ejection fraction in single ventricle. The anterior view should be used for region of interest selection and subsequent ejection fraction analyses.

Spinal meningeal uptake of technetium-99m methylene diphosphonate in meningeal seeding by malignant lymphoma.

Definite diagnosis of meningeal seeding by systemic cancer relies on the presence of malignant cells in the cerebrospinal fluid (CSF). In the absence of such cells in the CSF, only two other tests strongly suggest the diagnosis--a CT scan and a myelogram. We report a case in which the diagnosis was strongly suggested by an unusual uptake of Tc-99m methylene diphosphonate by the leptomeninges during a skeletal scan and later established by the presence of malignant cells in the CSF. We believe that radionuclide scan may be an additional diagnostic test in some cases with meningeal seeding by systemic cancer. We therefore are extending our studies to validate this possibility.