Radiotracer Accumulation Research Articles

False-positive Meckel's study in an ectopic pelvic kidney

A 30-year-old man with recurrent episodes of hematochezia underwent a Tc-99m pertechnetate study that showed, on anterior imaging, increased radiotracer accumulation just to the right of the midline in the anterior pelvis, near the aortic bifurcation into the common iliac arteries. However, during image acquisition, this abnormal accumulation of radiotracer diminished as the urinary bladder enlarged. The focal radiotracer accumulation was located in an ectopic right kidney within the true pelvis, which was confirmed by CT imaging. FIGURE 1Fig. 1: Sequential imaging of the abdomen after administration of Tc-99m pertechnetate shows rapid accumulation of radiotracer within the pelvis near the midline (arrow), with subsequent washout of radiotracer with time.FIGURE 2Fig. 2: A contrast-enhanced CT of the pelvis shows an ectopic pelvic right kidney (white arrows) (1–4).

Spontaneous intracranial hypotension

Purpose: To describe a patient with classic presentation of spontaneous intracranial hypotension and subsequent improvement with targeted epidural blood patch. Methods: Report of one case and review of the literature. Results: Examination of cerebrospinal fluid after lumbar puncture disclosed a reduced opening pressure, an increased level of protein, and lymphocytic pleocytosis. Magnetic resonance imaging of the brain with gadolinium showed diffuse enhancement of the pachymeninges, no evidence of leptomeningeal enhancement, and chronic subdural fluid collection. Radionuclide cisternography demonstrated reduced activity over the cerebral convexities, early accumulation of radiotracer in the urinary bladder, and direct evidence of leakage at the cervicothoracic junction (C 7-T 1). Clinical, laboratory, and radiologic features were consistent with the diagnosis of spontaneous intracranial hypotension. Therapy with a targeted epidural blood patch resulted in the rapid resolution of symptoms. Conclusions: In this report, we describe a classic case of spontaneous intracranial hypotension in a 63-year-old man with an initial presentation of postural headaches, blurred vision, pain in the left eye, diplopia on left gaze, and neck soreness.

Primary Hyperparathyroidism in Pregnancy: A Case Report

Primary hyperparathyroidism during pregnancy is a rare disorder. When managed inappropriately, it is associated with significant maternal and fetal morbidity. We present a pregnant woman who presented with hypercalcemia, hyperparathyroidism, and lower leg pain at 34 weeks' gestation. Radiography revealed multiple osteosclerotic nodules of the skull, subperiosteal resorption over the metacarpal bone, and pubic bone fracture. Primary hyperparathyroidism due to parathyroid adenoma was impressed. Normal saline and magnesium sulfate was administered, but was ineffective in controlling the hypercalcemia. At 35 weeks gestation, she delivered a health baby. However, the infant developed transient hypocalcemia 12 hours postpratum. After calcium supplement, the infant recovered well and was discharged 2 weeks pospartum. Postpartum parathyroid scan of the mother revealed radiotracer accumulation at the inferior right parathyroid level. She underwent parathyroidectomy at 3 weeks post delivery, which confirmed the presence of parathyroid adenoma. In conclusion, in cases of primary hyperparathyroidism during pregnancy, poor response to medical therapy may necessitate parathyroidectomy, even in third trimester. Neonatal hypocalcemia should be close monitored and prevented. The possibility of primary hyperparathyroidism should be considered in pregnant patients presenting with hypercalcemia, nephrolithiasis, or idiopathic bone fracture.

A simple probe measures the pharmacokinetics of [ [formula omitted]]RTI-55 in mouse brain in vivo

A simple external radiation detector system was used to assess brain 4-dopamine and serotonin transporters in mice in vivo using [ 125 I ]RTI-55. The results were compared to ex vivo dissection data. Methyl 3 β-(4-iodophenyl) tropane-2 β-carboxic acid methyl ester (RTI-55 or β-CIT), a high-affinity cocaine antagonist, binds to presynaptic dopamine and serotonin transporters in the brain. Radiotracer accumulation increased for the first 150 min after intravenous injection and then remained constant. When unlabeled RTI-55 was injected, either before or 60 min after radiotracer administration, a significant decrease in tracer accumulation was observed. [ 125 I ]RTI-55 binding was also displaced by blocking doses of 1-[2-[ bis(4-fluorophenyl)methoxy]ethyl]-4-[3-phenylpropyl]piperazine dihydrochloride (GBR 12909) and paroxetine. The results were similar to the ex vivo dissection data. The results demonstrate the feasibility of using the probe detector system to study the presynaptic transporter system in vivo in the mouse brain. The technique is applicable to other cerebral neurotransmitter systems.

Mutant mouse strains as models for in vivo radiotracer evaluations: [ 11C]methoxytetrabenazine ([ 11C]MTBZ) in Tottering mice

The regional brain distribution of [ 11C]methoxytetrabenazine ([ 11C]MTBZ), a high affinity radioligand for the vesicular monoamine transporter, has been examined in normal and tottering mice, which are neurological mutants. The tottering mice show significantly higher radiotracer accumulation (150–195% of controls) in all brain regions examined (striatum, cortex, hippocampus, hypothalamus, cerebellum and thalamus). The increases in [ 11C]MTBZ binding correlate ( r = 0.91) with the reported increases in norepinephrine concentrations in these regions, and are consistent with the noradrenergic hyperinnervation characteristic of the tottering mutant mouse. These studies demonstrate that a mutant mouse model of increased innervation can be used to evaluate the sensitivity of an in vivo radiotracer measure, in this case [ 11C]MTBZ binding to vesicular transporters, to an increase in the numbers of binding sites in specific regions of the brain.

Tellurium—speciation in seawater and accumulation by marine phytoplankton and crustaceans

Experiments were performed to determine the speciation of tellurium (using 129mTe as a radiotracer) in seawater and the extent of its accumulation by cultures of marine phytoplankton and crustaceans. Tellurite Te(IV) added to distilled water and to sterile filtered seawater was gradually transformed to the tellurate Te(VI) form, whereas Te(IV) tracer added to phytoplankton cultures was almost instantaneously transformed to a neutral form. Accumulation of radiotracer by phytoplankton ( Dunaliella tertiolecta and Thalassiosira pseudonana) was moderate and for Dunaliella was greater in static cultures than in those which were actively dividing. Equilibrium concentration factors of 20 and 8 were established respectively after up to seven days' exposure of the herbivorous brine shrimp ( Artemia salina) to labelled seawater with and without added phytoplankton. The loss of radionuclide upon transfer to uncontaminated running seawater was extensive and complete after one day, indicating that no true assimilation occurred. Transfer of radioactivity from Artemia salina to a predator, the Monaco shrimp ( Lysmata seticaudata), was not observed.

Jejunal Leiomyosarcoma Detected by Tc-99m Sulfur Colloid Gastrointestinal Bleeding Scan

Jejunal leiomyosarcoma was initially detected in a patient by a gastrointestinal bleeding scan with Tc-99m sulfur colloid (SC). The scan showed increased blood flow and delayed persistent accumulation of radiotracer in the tumor. The Tc-99m SC gastrointestinal bleeding scan provided useful information to help determine the differential diagnosis of gastrointestinal tumor with bleeding.

Whole lake addition of cadmium-109: radiotracer accumulation in the mussel population in the first season

Cadmium with the radiotracer 109Cd was added to the epilimnion of Precambrian Shield Lake 382 in the Experimental Lakes Area, northwestern Ontario to monitor pathways of Cd from water to abiotic and biotic components, to quantify Cd accumulation and distribution in biota and to evaluate adverse biological and ecological effects. This experiment will permit evaluation of the adequacy of the water quality guideline of 0.2 μg Cd l −1 in protecting aquatic life in softwater lakes. As part of the whole-lake experiment, we monitored the activities of 109Cd in various body parts of the floater mussel Anodonta grandis grandis to determine accumulation and distribution of Cd. Additions of Cd from 23 June to the end of October 1987 (a total of 900 g Cd and 89 mCi of 109Cd) increased the total [Cd] in the water from 1.6 to about 85 ng l −1. Cadmium-109 was accumulated in body parts of the mussels, in increasing concentration: mantle < foot < gill < visceral mass < kidney. After 4 months exposure to the increased water [Cd], the mussels had increased body burden of Cd by an estimated 5–9 times. At the latter increase, the population of 7330 ± 2100 mussels in the lake contained an estimated 0.011–0.020% of the added 109Cd.

DIAGNOSIS OF ACUTE HERPES SIMPLEX ENCEPHALITIS BY BRAIN PERFUSION SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY

Brain perfusion was studied in 14 patients with acute encephalitis by use of 123I-iodoamphetamine or 99mTc-hexamethylpropyleneamine oxime and single photon emission computed tomography (SPECT), the first examination being made 4-11 days after onset of encephalitis symptoms. All 6 patients with herpes simplex virus encephalitis (HSVE) had strongly increased accumulation of radiotracer in the affected temporal lobe; in the remaining 8 results were normal. At the time of the first SPECT conventional CT images were normal in all patients. The SPECT abnormality in HSVE gradually converted over 4-10 weeks from increased tracer accumulation to greatly subnormal accumulation. Brain perfusion SPECT may be helpful in the early diagnosis of HSVE.

The Angle of Louis

Evaluation of 100 consecutive Tc-99m MDP bone scans revealed in 36 patients a well defined area of increased accumulation of radiotracer at the Angle of Louis--the palpable ridge along the anterior surface of the sternum at the fibrocartilaginous junction of the sternum and manubrium. Twenty-five of the 36 patients had comparison radiographs; all were normal. None had sternal pain or a prior history of chest trauma. Increased uptake at the Angle of Louis ("Louie's Hot Spot") is a relatively common finding (36%) and should be recognized as a normal bone scan finding. It should not be confused with increased uptake due to an osseous abnormality, i.e., metastasis, degenerative disease, trauma, etc.

Diuretic radionuclide urography.

Diuretic radionuclide urography is a modification of conventional renography which utilizes the administration of intravenous furosemide to distinguish dilated, non-obstructed, hydronephrotic systems from those with significant mechanical obstruction. Diagnostic patterns are derived from computer generated time-activity histograms that depict the accumulation and washout of radiotracer before and after diuretic injection. In dilated but non-obstructed systems, diuresis produces a decline in activity. In obstructed systems, there is a failure of radiotracer washout in response to diuresis and no decline in activity is observed. The procedure is applicable to patients of all ages with suspected upper urinary tract obstruction. Clinical and experimental data support the accuracy and utility of this methodology and define its limitations and pitfalls.