Cerebral sparganosis: increased uptake of technetium-99m-HMPAO.

Cerebral sparganosis is an extremely rare intracranial parasitic infectious disease. We report findings of 99mTc-HMPAO cerebral perfusion SPECT in a case with cerebral sparganosis. SPECT revealed an irregularly shaped area with markedly increased 99mTc-HMPAO uptake in the parasitic infectious region of the cerebrum. Both white and gray matter was involved, the white matter involved predominantly. Decreased perfusion to the right cerebellum, suggesting cross cerebellar diaschisis, was also demonstrated. This article illustrates that cerebral sparganosis is one of the causes of increased 99mTc-HMPAO uptake in the cerebrum and should be considered clinically if present.

False-positive whole-body iodine-131 scan due to intrahepatic duct dilatation.

Focal retention of radioactivity in the liver on whole-body 131I scan was interpreted as a metastatic lesion in a patient with well-differentiated thyroid cancer. Intrahepatic duct dilatation, usually resulting from biliary tract obstruction by bile stone, is a common disorder and may cause bile stasis. A patient with papillary thyroid cancer and a previous history of biliary tract stones had focal retention of radioactivity in the liver on whole-body 131I scan. Abdominal CT, endoscopic retrograde cholagiopancreatography, radionuclide cholangiography and sequential 131I scans demonstrated that this focal retention of radioactivity was caused by intrahepatic duct dilatation. Focal retention of radioactivity is visualized on delayed images but not on early images. The radioactivity initially increases and then decreases on following days.

Longer occupancy of opioid receptors by nalmefene compared to naloxone as measured in vivo by a dual-detector system.

UNLABELLED: Surgical procedures usually involve the administration of narcotic drugs as anesthetics or adjuvants. To reverse the effects of anesthesia, opioid antagonists such as naloxone are commonly used. Due to its short lasting effects, patients receiving naloxone must be monitored carefully. Nalmefene, a pure opiate antagonist with a longer duration of action than naloxone, has shown promise in the reversal of opioid anesthesia. METHODS: A simple dual-detector positron radiation detector system and [11C]carfentanil were used to compare the duration of blockade of cerebral mu opioid receptors by naloxone and nalmefene in eight normal volunteers. Carbon-11-carfentanil brain kinetics were monitored for 5 min and 2, 4, 8 and 24 hr after the administration of either nalmefene (1 mg or 1 microg/kg) or naloxone (2 mg or 2 microg/kg). Blood samples were obtained at the same times for plasma determinations. RESULTS: Clearance half-times from opioid receptors were 28.7 +/- 5.9 hr for 1 mg of nalmefene and 2.0 +/- 1.6 hr for 2 mg of naloxone. Brain clearance times were about 21.1 and 3.4 times slower than plasma clearance times for nalmefene and naloxone, respectively. CONCLUSION: These findings suggest that the prolonged effects of nalmefene are related to the slow dissociation of nalmefene from opioid receptors, which are not reflected in the plasma curve. This longer blockade of opioid receptors by nalmefene represents an advantage in the clinical management of postsurgical reversal of narcotic anesthesia and opioid side effects as well as the reversal of opioid overdose.

Decreased dopamine transporter binding in Machado-Joseph disease.

UNLABELLED: The aim of this study was to use 99mTc-TRODAT-1 brain SPECT for investigation of the binding of dopamine transporter (DAT) in the nigrostriatal dopaminergic pathway of symptomatic Machado-Joseph disease (MJD) and to compare the results with the abnormal cytidylate, adenylate, and guanylate (CAG) expansion in the MJD1 gene and other clinical factors. METHODS: Ten symptomatic MJD patients (8 women, 2 men; age range, 20-71 y; mean age +/- SD, 36.4 +/- 10.6 y; mean duration of illness, 9.8 +/- 5.4 y) and 21 healthy volunteers (age range, 24-71 y; mean age, 47.6 +/- 20.1 y) were examined. Brain SPECT images were acquired 4 h after injection. The ratio of specific to nonspecific nigrostriatal 99mTc-TRODAT-1 binding was measured and compared with the clinical symptoms, duration of illness, and size of abnormal expanded CAG repeats. RESULTS: All nigrostriatal 99mTc-TRODAT-1 ratios were significantly lower in MJD patients than in healthy volunteers (P < 0.05). Discriminant function analysis of all MJD patients showed that the decreased binding of 99mTc-TRODAT-1 in the putamen was not significantly different from that in the caudate nucleus. Eight of 10 MJD patients had significantly decreased 99mTc-TRODAT-1 uptake. Of these 8, 2 had extrapyramidal signs and 6 had no obvious extrapyramidal signs. The other 2 patients, who had normal 99mTc-TRODAT-1 uptake, had no obvious extrapyramidal signs. CONCLUSION: Our findings indicate that 99mTc-TRODAT-1 brain SPECT is an appropriate method for evaluating damage to the nigrostriatal DAT in symptomatic MJD patients with and without extrapyramidal signs. The decreased binding of 99mTc-TRODAT-1 in the nigrostriatal dopaminergic pathway in symptomatic MJD patients correlates with the phenotype of extrapyramidal signs but not with the abnormal CAG repeat length, age at disease onset, or disease duration.

Enhanced uptake of [11C]TPMP in canine brain tumor: a PET study.

UNLABELLED: In vitro studies have demonstrated the membrane potential-dependent enhanced uptake of phosphonium salts, including [3H]triphenylmethylphosphonium (TPMP), into mitochondria of carcinoma and glioma-derived tumor cells, suggesting the potential use of phosphonium salts as tracers for tumor imaging. This study characterizes the in vivo uptake of [11C]TPMP in canine brain glioma using PET. METHODS: Dynamic paired PET studies of [11C]TPMP followed by [68Ga]ethylenediaminetetraacetic acid (EDTA) were performed 4 d before and 9 d after tumor cell inoculation. Graphical analysis was used to evaluate [11C]TPMP retention in tumor tissue. Distribution of tracer uptake was compared with tumor histological sections. RESULTS: [11C]TPMP exhibited enhanced uptake and prolonged retention in tumor cells. Patlak plot was linear over the 20- to 95-min postinjection period (r = 0.97 +/- 0.1). [68Ga]EDTA exhibited a gradual washout from the tumor tissue. The tumor-to-normal brain uptake ratio at 55 to 95 min postinjection was 47.5 for [11C]TPMP and 8.1 for [68Ga]EDTA. Qualitative comparison with histological sections indicated that [11C]TPMP enhanced uptake was restricted to the tumor area. CONCLUSION: The enhanced uptake and prolonged retention in tumor suggest [11C]TPMP as a promising means for imaging of gliomas in dogs. The need for studies in humans is indicated.

Investigation of angiotensin II/AT1 receptors with carbon-11-L-159,884: a selective AT1 antagonist.

UNLABELLED: Antagonists of the angiotensin II AT1 receptor subtype have been recently introduced for treatment of arterial hypertension and for pharmacological studies of these receptors. The purpose of this work was to label such an antagonist with 11C and test the applicability of the radioligand for PET studies. METHODS: The potent and selective nonpeptide AT1 antagonist L-159,884 was labeled with 11C and injected intravenously into six dogs. Renal accumulation and kinetics of the radioligand were imaged with PET at baseline and after receptor blockade with 1 mg/kg MK-996. Time-activity curves were derived from the renal cortex and were analyzed by the Gjedde-Patlak plot to obtain the influx rate constant of the radioligand. RESULTS: There was selective radioligand binding in the kidneys, mainly located in the cortex. Within the time interval between 95 and 115 min postinjection, the radioactivity retained in the kidneys was 109 +/- 27 and 42 +/- 4 nCi/ml/mCi of the injected dose for the control and inhibition studies, respectively. The influx rate constant of the radioligand decreased from a baseline of 0.0298 +/- 0.0156 to a post-MK-996 value of 0.0098 +/- 0.0052. CONCLUSION: These results demonstrate distinct binding of 11C-L-159,884 in the renal cortex with a specific binding component suitable for quantitative PET imaging of angiotensin II/AT1 receptors.

Positron emission tomography of 5-HT reuptake sites in the human brain with C-11 McN5652 extraction of characteristic images by artificial neural network analysis.

The goal of this work was to identify the distribution of serotonin transporters in the human brain with [11C](+)McN5652/PET. Four healthy volunteers were studied. To determine non-specific binding, a PET study was also performed with the inactive enantiomer [11C](-)McN5652 as well as with [11C](+)McN5652 after pretreatment with fluoxetine. For pattern extraction the PET data sets were analyzed by a back-propagation neural network. Two pharmacokinetic patterns and two characteristic images were separated; one representing specific binding, the other representing non-specific binding. The specific binding image showed characteristic distribution of serotonin transporters with [11C](+)McN5652. The pattern images demonstrated an improvement in image quality compared to the original PET images (reduced variance, higher region-to-cerebellum ratio, good correlation with known density of serotonin transporters). The non-specific binding images extracted from [11C](-)McN5652/PET were similar to those of [11C](-)McN5652 and [11C](-)McN5652 with fluoxetine. Thus, PET studies obtained with [11C](+)McN5652 largely represent the regional distribution of the serotonin transporters and the inactive enantiomer [11C](-)McN5652 shows the distribution of its nonspecific binding.

Quantitative cerebral perfusion SPECT in systemic lupus erythematosus with severe central nervous involvement--before and after methylprednisolone pulse therapy.

Severe cerebral involvement may occur in patients with systemic lupus erythematosus. Methylprednisolone pulse therapy is a management choice for those with severe cerebral involvement. However, its effectiveness is uncertain. This article describes Tc-99m HMPAO cerebral perfusion single-photon emission computerized tomography to document the restoration of cerebral perfusion after methylprednisolone pulse therapy in a case of systemic lupus erythromatosus with severe cerebral manifestations.

Characterization of the calcaneal fat pad in diabetic and non-diabetic patients using magnetic resonance imaging.

It is well known that diabetic patients have a high incidence of foot ulceration. The purpose of this study was to determine whether magnetic resonance (MR) imaging can detect changes in the composition of the calcaneal fat pad in diabetic feet. MR data were collected in vitro from amputated specimens (eight from diabetic patients and eight from non-diabetic patients) as well as in vivo from age-matched diabetic and control subjects (four subjects each group.) Three types of images were acquired: spin lattice (T1), spin-spin (T2), and magnetization transfer (MT). The in vitro results showed statistically significant differences in the T1, T2, and MT parameters between the two disease groups. The same trends were shown in the study of live subjects but the differences were not statistically significant. The differences are believed to arise from changes in the composition of the tissues as a result of the progression of diabetes.

The effects of radioactive iodine in thyroid remnant ablation and treatment of well differentiated thyroid carcinoma.

Although the use of radioactive iodine (131I) in the treatment of thyroid cancer is well established, treatment dose is not well standardized. In order to deduce the appropriate dose for thyroid remnant ablation and the effect of 131I in the treatment of distant metastases, data for 544 patients with papillary or follicular thyroid cancer were retrospectively reviewed. All patients received surgical treatment followed by post-operative 131I. If remnants were present in the 0.2 GBq 131I diagnostic scan, 1.1-3.7 GBq 131I were administered for ablation. For the treatment of distant metastases 3.7-5.6 GBq were used. Of 318 patients receiving 131I for thyroid remnant ablation, 290 were successfully ablated. After one dose of 1.1 GBq 131I, 82% (159/194) of thyroid remnants were ablated. During the follow-up period, two of 14 Stage IV patients with lung or mediastinal metastases at the time of operation achieved complete clinical remission. Factors identified as influencing response to 131I therapy included age, clinical stage, survival, recurrence, extent of surgery and the 1 month post-operative serum thyroglobulin (Tg) level. In conclusion 1.1 GBq 131I was adequate for thyroid remnant ablation unless distant metastases were present. Radioactive 131I has a role in the treatment of well differentiated thyroid carcinoma with pulmonary metastases but seems to be less effective for treatment of bone metastases.

Diuretic renography findings in enterovesical fistula.

A 73-year-old male presented with a 2 week history of gross haematuria and faecal material in the urine. Bone scan for cancer work-up showed 99T(cm)-MDP radioactivity accumulation in the transverse and descending colon. A 99T(cm)-DTPA diuretic renogram was arranged to study renal function and to determine the location of the enterovesical fistula. Diuretic renography demonstrated extraurinary tract radioactivity in the sigmoid colon in the early images, extending to the descending and transverse colon in the subsequent dynamic images. A sigmoid colon adenocarcinoma with bladder wall invasion and fistula formation was confirmed at surgical operation. The impressive dynamic diuretic renography study in this patient was helpful in determining the location of the fistula and in planning surgical management.

Breast uptake of iodine-131 mimicking lung metastases in a thyroid cancer patient with a pituitary tumour.

We report a case of a 44-year-old female thyroid cancer patient with a pituitary tumour. 131I whole body scanning showed a change of chest uptake from a unilateral crescent uptake to a bilateral full breast uptake pattern. Hyperprolactinaemia and a pituitary tumour were diagnosed as a result of observing the 131I breast uptake.

Cerebral perfusion SPECT in transient ischemic attack.

PURPOSE: The purpose of our study is to evaluate the efficacy of cerebral perfusion single photon emission computerized tomography (SPECT) in patients with transient ischemic attack (TIA). METHODS: Thirty-seven patients with TIA were collected for study. All patients had transient focal neurological symptoms or signs with complete recovery within 24 h after onset. The patients underwent cerebral perfusion SPECT between 6 h and 11 days after onset, with 10 cases performed within 24 h (group A), nine cases performed between 1 and 3 days (group B), 11 cases performed between 3 and 5 days (group C), and seven cases performed after more than 5 days (group D). A semi-quantitative method was used for analyzing the SPECT data, and the difference ratios between lesion side and contralateral normal side were calculated on each pair of regions of interest. RESULTS: In total, 78.4% (29/37) of patients had reduced perfusion in the cerebral cortical regions or deep nuclei, and the regions with reduced perfusion corresponded with clinical presentations of the patients. The abnormal rate with reduced perfusion was 90.0% in group A, 77.8% in group B, 72.7% in group C and 71.4% in group D. Cross cerebellar diaschisis (CCD) was present in seven patients, and all of the primary cerebral perfusion defects of these patients were located at the territory of left or right middle cerebral artery. CONCLUSION: Cerebral perfusion SPECT is a potential tool to detect cerebral perfusion defects and CCD in patients with TIA. Although the perfusion defect may persist more than 5 days after onset, we suggest cerebral perfusion SPECT should be performed as soon as possible.

99Tcm-MDP scintigraphy in high-voltage electrical burn patients.

In high-voltage electrical burn injuries (> 1000 V), it is difficult to identify the site and extent of non-viable deep tissue damage for debridement to avoid further tissue injury from wound infection and the risk of sepsis. This prospective study was designed to evaluate the usefulness of 99Tcm-methylene di-phosphonate (99Tcm-MDP) scintigraphy in detecting the extent of tissue injury and determining the level of amputation required for electrical burn patients. Over a 5 year period, 33 high-voltage electrical burn patients were studied. Blood flow and blood pool studies revealed absent perfusion in 37 limbs, all of which eventually were amputated. In addition to a routine three-phase bone scan, images were obtained at 30-60 min (early images) to evaluate whether soft tissue injury could be detected better at that time. For comparison of the detection rate from the early images and bone (delayed) images, 164 corresponding spot views of both images were reviewed. Eighty-three and 125 tissue necrotic lesions were demonstrated by the early images and bone images respectively. All of the 83 lesions found by the early images were more clearly identified by the bone images. All but one of the 125 lesions underwent surgical debridement or amputation. We concluded that the blood flow and blood pool images correlated well with the level of amputation required. The site and extent of tissue necrotic lesions can be clearly identified on 99Tcm-MDP bone scans. Because the early images were less sensitive in detecting tissue necrosis, we suggest that early imaging is not necessary.

Investigation of pulmonary epithelial permeability in patients after hyperbaric oxygen therapy by 99mTc diethylenetriaminepentaacetic acid aerosol inhalation lung scintigraphy.

The aim of this study was to evaluate the possibility of pulmonary epithelial permeability damage in patients after hyperbaric oxygen therapy (HBOT) by 99mTc diethylenetriaminepentaacetic acid (99mTc-DTPA) aerosol inhalation lung scintigraphy. Twenty-five controls and 21 patients with normal chest X-rays and no cigarette smoking for at least 1 year were recruited for the study. 99mTc-DTPA aerosol inhalation lung scans were performed after 20 HBOT sessions in 21 patients with refractory osteomyelitis or diabetic foot. The HBOT with 100% oxygen at 2.5 atm absolute for 100 min was performed five times a week. Clearance rates (%/min) of 99mTc-DTPA aerosol in each lung field were calculated from the dynamic images for 30 min. Clearance rates of 99mTc-DTPA aerosol were compared between patients and controls by the unpaired t test. Thirteen patients who had 99mTc-DTPA aerosol lung scans before and after HBOT therapy studies were tested for statistical significance by using the paired t test. There was no statistically significant difference (P>0.05, unpaired t test) between patients and controls in every lung field. For the 13 patients who had 99mTc-DTPA aerosol studies both before and after 20 HBOT sessions, the results also showed no statistically significant difference (P>0.05, paired t test). It is concluded that there was no demonstrable pulmonary epithelial permeability change under current clinical HBOT protocol.

The 99mTc-DMSA renal scan and 99mTc-DTPA diuretic renogram in children and adolescents with incidental diagnosis of horseshoe kidney.

A prospective study was conducted to determine the possibility of obstructive hydronephrosis in horseshoe kidney found incidentally in school children and adolescents by using a radionuclide diuretic renogram. In a 2-year period, 22 school children and adolescents with horseshoe kidney were found in a mass renal sonography survey. They each underwent a 99mTc dimercaptosuccinic acid renal cortical scan to confirm the horseshoe kidney. Each diuretic renogram was performed with the patient in the supine position to rule out obstructive hydronephrosis. The patients were advised to empty their bladders before the intravenous injection of furosemide (1 mg x kg(-1)). The half-time for the clearance of radioactivity from the renal pelvis were calculated. Of the 22 patients, asymmetrical renal cortical function between the two kidneys was found in 14 (63.6%). Eleven kidneys (11/44, 25%) showed stasis of radioactive urine in the renal pelvic region prior to injection of furosemide. There was no incidence of bilateral hydronephrosis in these 22 patients. Only one kidney (1/44, 2.3%) showed obstructive hydronephrosis and five showed clearance of radioactive urine stasis from the renal pelvis immediately after standing up for voiding. There is a low percentage of obstructive hydronephrosis in these cases of horseshoe kidney found incidentally in children and adolescents. A follow-up cohort study on these patients would be valuable for monitoring the development of complications.

The role of 67Ga in the early detection of spinal epidural abscesses.

In this study, we evaluated the role of 67Ga whole-body and single photon emission tomographic (SPET) imaging in the early diagnosis and lesion localization of spinal epidural abscess before confirmation by gadolinium-enhanced magnetic resonance imaging (MRI). Six patients with fever of unknown origin had a 67Ga whole-body scan, four of whom also underwent SPET imaging. For further confirmation of a spinal epidural abscess, gadolinium-enhanced MRI was performed in all patients. All patients had increased 67Ga uptake in a spinal or paraspinal area on the whole-body scan. They were later confirmed to have a spinal epidural abscess after gadolinium-enhanced MRI. Of these six patients, five underwent surgical drainage plus parenterally administered antibiotics, and had complete or partial recovery. One died before operation due to sepsis. In conclusion, we suggest performing a 67Ga whole-body survey as early as possible in patients with fever of unknown origin, fever and back pain and/or the spinal syndrome, before MRI is performed. If a spinal epidural abscess is strongly suspected, SPET is needed for further confirmation of spinal versus non-spinal and contiguous versus non-contiguous lesion(s). If MRI is unavailable, then 67Ga scintigraphy is a satisfactory method for investigating spinal epidural abscesses.

The optimal imaging time for [99Tcm]TRODAT-1/SPET in normal subjects and patients with Parkinson's disease.

Imaging of dopamine transporters (DATs) in the brain using [99Tcm]TRODAT-1 showed excellent pharmacokinetics for estimation of transporter concentrations. It has been reported that there may be differences in the binding kinetics of DAT radiotracers to DATs between normal subjects and patients with Parkinson's disease (PD). The aim of this study was to determine an optimal time point for (99Tcm]TRODAT-1 brain single photon emission tomography (SPET) acquisition that provides stable target to non-target ratios reflecting the DAT concentration in the brain. Serial [99Tcm]TRODAT-1 brain SPET images 2, 3 and 4 h after intravenous injection of [99Tcm]TRODAT-1 (925 MBq) were performed in five healthy subjects and nine PD patients. Regions of interests were drawn, and caudate/occipital (C/O) and putamen/occipital (P/O) specific to non-specific [99Tcm]TRODAT-1 binding ratios were calculated. The C/O and P/O ratios in healthy subjects showed consistent increases with time, but in PD patients, the C/O and P/O ratios of [99Tcm]TRODAT-1 reached a stable level at 3 h post-injection. There was a statistically significant difference (P < 0.001) between PD and normal subjects at 4 h post-injection for both the C/O and the P/O ratios. In conclusion, we recommend the acquisition of [99Tcm]TRODAT-1 SPET images at 4 h post-injection, as at this time point the C/O and P/O ratios can be used to discriminate between PD patients and healthy subjects.

Ectopic ACTH syndrome due to thymic carcinoid tumor in a girl.

An 8 year-old girl had a cushingoid appearance for six months. Hormone study showed extremely high serum levels of cortisol (> 60 micrograms/dl) and adrenocorticotropic hormone (930 pg/ml). Initial chest X-ray showed nothing unusual, but a technetium-99mm MIBI scan showed an accumulation lesion in the left upper chest cavity. Chest magnetic resonance imaging demonstrated that the mass was in the superior anterior mediastinum. She had complete removal of the tumor with partial thymectomy. The pathology revealed a thymic carcinoid tumor. Carcinoid tumors of the thymus are extremely rare in children and they usually present with Cushing's syndrome. To our knowledge, this is the youngest patient who has ever been reported with this disease.

Using a computerized method to measure 99mTc pertechnetate uptake for the assessment of thyroid function: a clinical validation.

This retrospective study evaluated thyroid function by the 99mTc pertechnetate uptake ratio, using computer software designed in our laboratory. We expected that this measurement could be a precise and accurate index. The following studies were performed on 187 patients: (1) 24-hour radioimmunoassay of serum thyroid hormones, including serum thyroxine, free T4, triiodothyronine, thyrotropin concentrations, and T3 resin uptake; (2) 99mTc pertechnetate thyroid imaging and uptake measurement; and (3) 24-hour 131I thyroid uptake. Based on the clinical findings and the results from the predescribed laboratory tests, we found that: (1) the mean value of the 99mTc pertechnetate thyroid uptake ratio in the euthyroid groups was 2.77 +/- 1.77% (mean +/- SD); (2) the correlation coefficient between the 99mTc pertechnetate thyroid uptakes and the 24-hour 131I uptakes of the euthyroid patients was 0.71; and (3) hyperthyroidism could be distinguished from euthyroid condition easily. By setting the upper limit of euthyroid 99mTc pertechnetate thyroid uptake at 6.31%, the diagnostic sensitivity was 92.9%, specificity 96.1%, and accuracy 95.6% in separating hyperthyroid from euthyroid patients. These values were similar to those determined by the 24-hour 131I uptake measurements. Thus, thyroid function can be evaluated simultaneously with a routine 99mTc pertechnetate thyroid scan. Both the patient time and cost can be saved with this method, since the measurement takes only 25 minutes. Decreased radiation exposure is another advantage of this method over the traditional 131I uptake measurement.