Accuracy of quantitative reconstructions in SPECT/CT imaging.

The goal of this study was to determine the quantitative accuracy of our OSEM-APDI reconstruction method based on SPECT/CT imaging for Tc-99m, In-111, I-123, and I-131 isotopes. Phantom studies were performed on a SPECT/low-dose multislice CT system (Infinia-Hawkeye-4 slice, GE Healthcare) using clinical acquisition protocols. Two radioactive sources were centrally and peripherally placed inside an anthropometric Thorax phantom filled with non-radioactive water. Corrections for attenuation, scatter, collimator blurring and collimator septal penetration were applied and their contribution to the overall accuracy of the reconstruction was evaluated. Reconstruction with the most comprehensive set of corrections resulted in activity estimation with error levels of 3-5% for all the isotopes.

Does preoperative positron emission tomography with computed tomography predict nodal status in endometrial cancer? A pilot study.

Fewer than 20% of women with endometrial cancer have positive nodes, and an accurate noninvasive imaging modality to assess lymph node status would be helpful in selecting those who need lymphadenectomy. The objective of this pilot study was to evaluate positron emission tomography with computed tomography (pet-ct) in predicting nodal status before surgery for endometrial cancer. Twelve patients were enrolled at a single tertiary care centre. The sensitivity and specificity of preoperative pet-ct in predicting nodal status were 53.3% and 99.6% respectively. Using pet-ct, all metastatic nodes may not necessarily be detected, especially nodes with microscopic disease. The sensitivity of this imaging modality has to be improved before it can routinely be used in the preoperative evaluation of endometrial cancer.

Radioiodine ablation of thyroid remnants after preparation with recombinant human thyrotropin in differentiated thyroid carcinoma: results of an international, randomized, controlled study.

CONTEXT: After surgery for differentiated thyroid carcinoma, many patients are treated with radioiodine to ablate remnant thyroid tissue. This procedure has been performed with the patient in the hypothyroid state to promote endogenous TSH stimulation and is often associated with hypothyroid symptoms and impaired quality of life. OBJECTIVE AND INTERVENTION: This international, randomized, controlled, multicenter trial aimed to compare the efficacy and safety of recombinant human TSH (rhTSH) to prepare euthyroid patients on L-thyroxine therapy (euthyroid group) to ablate remnant thyroid tissue with 3.7 GBq (100 mCi) 131I, compared with that with conventional remnant ablation performed in the hypothyroid state (hypothyroid group). Quality of life was determined at the time of randomization and ablation. After the administration of the 131-I dose, the rate of radiation clearance from blood, thyroid remnant, and whole body was measured. RESULTS: The predefined primary criterion for successful ablation was "no visible uptake in the thyroid bed, or if visible, fractional uptake less than 0.1%" on neck scans performed 8 months after therapy and was satisfied in 100% of patients in both groups. A secondary criterion for ablation, an rhTSH-stimulated serum thyroglobulin concentration less than 2 ng/ml, was fulfilled by 23 of 24 (96%) euthyroid patients and 18 of 21 (86%) hypothyroid patients (P = 0.2341). Quality of life was well preserved in the euthyroid group, compared with the hypothyroid group, as demonstrated by their lower pretreatment scores on the Billewicz scale for hypothyroid signs and symptoms, 27 +/- 7 vs. 18 +/- 4 (P < 0.0001) and their significantly higher Short Form-36 Health Assessment Scale scores in five of eight categories. Euthyroid patients had a statistically significant one third lower radiation dose to the blood, compared with patients in the hypothyroid group. CONCLUSIONS: This study demonstrates comparable remnant ablation rates in patients prepared for 131I remnant ablation with 3.7 GBq by either administering rhTSH or withholding thyroid hormone. rhTSH-prepared patients maintained a higher quality of life and received less radiation exposure to the blood.

A pragmatic protocol for I-131 rhTSH-stimulated ablation therapy in patients with renal failure.

PURPOSE: Ablation of thyroid remnants in patients with differentiated thyroid carcinoma and renal failure can be challenging because of the altered and variable clearance rates of iodine from the blood secondary to variations in dialysis protocols, which complicate the selection of the appropriate I-131 dose. The advent of recombinant human TSH allows a simpler approach to dosimetry and ablation without rendering the patient hypothyroid. Avoidance of hypothyroidism may be an important consideration for patients who are experiencing various morbidities from conditions associated with renal failure. METHOD: Three patients on dialysis, who had undergone total thyroidectomy and were euthyroid on L-thyroxine replacement, were given diagnostic doses of I-131 followed by blood and whole-body retention measurements through serial dialyses to determine individual blood clearance rates. After administration of rhTSH, each patient received an ablative dose of I-131 calculated to keep total body dose below 1 Gy. RESULTS: The treatments were administered without complications, and in follow-up imaging of 2 available patients, the ablations were demonstrated to be complete. CONCLUSION: Dosimetry performed on euthyroid dialysis patients permits I-131 dose selection and avoids the additional morbidity of hypothyroidism.

Insulin protects against hepatic bioenergetic deterioration induced by cancer cachexia: an in vivo 31P magnetic resonance spectroscopy study.

The bioenergetic effects of cancer cachexia on the livers of male Fischer rats inoculated with a methylcholanthrene-induced sarcoma were assessed using serial in vivo 31P magnetic resonance spectroscopy. Rats were randomized into three groups: tumor-bearing controls (n = 7); an insulin-treated group receiving 2 units/100 g body weight/day starting 21 days after implantation (n = 8); and a chronic insulin-treated group receiving insulin every day after implantation (n = 3). During the 32-day study, serial measurements of food intake, body weight, and tumor volume were taken, and 31P magnetic resonance spectroscopy analyses of the livers were conducted every 7 days after tumor implantation. Neither the short-term nor the chronic insulin treatment regimens stimulated the progress of tumor growth. However, both treatments prevented body weight loss, and the short-term insulin treatment prevented tumor-induced decrease in food intake relative to the control group. Liver bioenergetic deterioration was evaluated from the increase in the ratio of Pi to ATP obtained from the hepatic 31P magnetic resonance spectra. At day 28 postimplantation, control rats exhibited appreciable hepatic bioenergetic deterioration, i.e., a Pi/ATP ratio of 1.41 +/- 0.35 (SE), significantly higher (P < 0.05) than the Pi/ATP ratio for short-term or chronic insulin treatment groups (Pi/ATP 0.92 +/- 0.22 and 0.84 +/- 0.22, respectively) or rats before tumor implantation (Pi/ATP 0.76 +/- 0.14). This insulin-induced bioenergetic protection occurred at any given tumor burden up to at least 10%. Thus, both short-term insulin given just prior to the frank manifestations of cancer cachexia and chronic insulin treatment given throughout tumor growth ameliorated host hepatic bioenergetic deterioration without significantly stimulating tumor growth. Insulin may act by altering the host metabolism (stimulation of liver glucose uptake and utilization, decreased energy-requiring gluconeogenesis, and general protein-sparing action) at the expense of the tumor.

Effect of cancer on the in vivo energy state of rat liver and skeletal muscle.

The effect of increasing tumor burden on host liver and skeletal muscle energy status was studied using P-31 nuclear magnetic resonance spectroscopy (NMR), in rats inoculated with a nonmetastasizing methylcholanthrene-induced sarcoma (TB), and compared to nontumor bearing (NTB) and pair-fed (PF) rats. During the 28-day study, serial measurements of body weight, food intake, and tumor volume were obtained. Using a 0.9-cm double-turn surface coil, weekly NMR measurements were obtained from liver and skeletal muscle. An increasing ratio of [Pi]/[ATP] was used as one measure of intracellular energy depletion. [Pi]/[ATP] in NTB rats remained constant over time at 0.78 +/- 0.10 in liver, and 0.30 +/- 0.10 in skeletal muscle. In TB rats, the [Pi]/[ATP] ratio increased significantly in liver (P = 0.00002) and skeletal muscle (P = 0.04) with increasing tumor burden. In PF rats, no significant change occurred in [Pi]/[ATP] in liver or skeletal muscle, indicating that declining food intake was not responsible for the change in [Pi]/[ATP] seen in TB rats. Surface-coil spectroscopy of liver and skeletal muscle permits serial measurement of visceral energy stores. Increasing tumor burden results in early, ongoing depletion of energy stores as reflected by increasing [Pi]/[ATP] in these organs.

Lack of significant long-term sequelae following traumatic myocardial contusion.

We assessed the possibility of long-term functional cardiac sequelae in patients who had sustained a traumatic myocardial contusion (group 1) by comparing this group with a cohort group of patients with similar traumatic injuries but exclusive of the cardiac component (group 2). More than one year following injury, patients in group 1 were qualitatively indistinguishable from patients in group 2 according to the New York Heart Association classification. Both the left and the right ventricular ejection fractions, less in group 1 than in group 2 immediately following trauma, were similar between groups during follow-up study at rest. During exercise to maximal work load at follow-up, changes in the mean right and left ventricular ejection fractions were also similar between the two patient groups. We therefore concluded that traumatic myocardial contusion to the left and/or right ventricle almost always resolves without significant functional sequelae within one year of injury.

Two cases of thyroid carcinoma that were not stimulated by recombinant human thyrotropin.

Recombinant human TSH (rhTSH) is being widely used to monitor patients who were previously treated for differentiated thyroid cancers for evidence of recurrence. Its value lies in the avoidance of recurrent episodes of hypothyroidism in the follow-up protocols. rhTSH is also being evaluated as a potential therapeutic adjunct that would spare patients the experience of becoming hypothyroid when undergoing thyroid remnant ablation or treatment for metastases. In some centers, rhTSH is also used to support compassionate care of patients with advanced disease who cannot safely become hypothyroid. The (131)I uptake response to rhTSH, presently an off-label application, is expected to be similar to that of endogenously raised TSH levels. The two cases presented here are cautionary tales in which (131)I uptake by metastases was present under hypothyroid conditions, but absent in one patient and present in only a portion of the lesions in the other, with rhTSH stimulation.

Hypophosphatemia and respiratory failure: prolonged abnormal energy metabolism demonstrated by nuclear magnetic resonance spectroscopy.

Hypophosphatemia has been shown to cause acute respiratory failure. The mechanism is believed to be due to decreased high-energy substrate availability at the cellular level leading to respiratory muscle dysfunction. However, direct measurement of these substrates has not been previously studied. A patient with hypophosphatemic respiratory failure is described in whom phosphocreatine and pH were continuously monitored using nuclear magnetic resonance spectroscopy. This revealed a defect in muscle metabolism that required several weeks to recover despite prompt correction of the serum phosphate level.

Preparation and evaluation of radioiodinated (iodophenyl)cholines and their morpholinium and piperidinium analogues as myocardial perfusion imaging agents.

A series of nine radioiodinated quaternary ammonium salts related to phenylcholine were synthesized, characterized, and radiolabeled by exchange. These compounds were evaluated as myocardial perfusion imaging agents in mice, pigs, and humans. Mice biodistribution studies showed that five of the nine compounds were taken up in the heart to the same extent as 201Tl+ at 5 min. At 60 min myocardial retention was significantly better than 201Tl+ for six of the compounds. Several of the compounds showed more favorable heart/blood and heart/liver ratios when compared to 201Tl+. Evaluation of three of the more promising compounds in pigs and humans however revealed no selective myocardial uptake.

Effect of obstructed mediastinal venous return on dynamic brain blood flow studies: Case report.

Three patients are described who had unusual isotope brain flow studies in which the injected isotope refluxed into the internal jugular vein, entered the transverse dural sinuses, and returned proximally to a variable extent through the contralateral internal jugular vein. Mediastinal flow studies revealed obstructed pathways of venous return in the upper mediastinum. One patient had lymphoma, another had had a pneumonectomy, and the third had no demonstrable disease process to explain the flow pattern. The internal jugular-cerebral system apparently permits reversal of flow in the presence of unilateral obstruction proximal to the internal jugular vein.

Java-based remote viewing and processing of nuclear medicine images: toward "the imaging department without walls".

UNLABELLED: In nuclear medicine practice, images often need to be reviewed and reports prepared from locations outside the department, usually in the form of hard copy. Although hard-copy images are simple and portable, they do not offer electronic data search and image manipulation capabilities. On the other hand, picture archiving and communication systems or dedicated workstations cannot be easily deployed at numerous locations. To solve this problem, we propose a Java-based remote viewing station (JaRViS) for the reading and reporting of nuclear medicine images using Internet browser technology. METHODS: JaRViS interfaces to the clinical patient database of a nuclear medicine workstation. All JaRViS software resides on a nuclear medicine department server. The contents of the clinical database can be searched by a browser interface after providing a password. Compressed images with the Java applet and color lookup tables are downloaded on the client side. This paradigm does not require nuclear medicine software to reside on remote computers, which simplifies support and deployment of such a system. To enable versatile reporting of the images, color tables and thresholds can be interactively manipulated and images can be displayed in a variety of layouts. Image filtering, frame grouping (adding frames), and movie display are available. Tomographic mode displays are supported, including gated SPECT. RESULTS: The time to display 14 lung perfusion images in 128 x 128 matrix together with the Java applet and color lookup tables over a V.90 modem is <1 min. SPECT and PET slice reorientation is interactive (<1 s). JaRViS could run on a Windows 95/98/NT or a Macintosh platform with Netscape Communicator or Microsoft Intemet Explorer. The performance of Java code for bilinear interpolation, cine display, and filtering approaches that of a standard imaging workstation. CONCLUSION: It is feasible to set up a remote nuclear medicine viewing station using Java and an Internet or intranet browser. Images can be made easily and cost-effectively available to referring physicians and ambulatory clinics within and outside of the hospital, providing a convenient alternative to film media. We also find this system useful in home reporting of emergency procedures such as lung ventilation-perfusion scans or dynamic studies.

Persistent dural cerebrospinal fluid leak shown by retrograde radionuclide myelography: case report.

Following inadvertent spinal anesthesia for delivery, a patient developed incapacitating post-lumbar puncture headache that persisted for 9 weeks. Scintigrams of the lumbar region, obtained after injection of 99mTC-human serum albumin into the cisterna magna, showed the cerebrospinal fluid leak. Blood patch repair was carried out, with immediate relief of all symptoms. Because of subsequent atypical headaches, a second cisternogram was done by the same technique. This study confirmed that there was no further dural leak, and other evidence indicated that the recurrent headache was related to functional problems.

In vivo red blood cell compatibility testing using indium-113m tropolone-labeled red blood cells.

In vivo radionuclide crossmatch is a method for identifying compatible blood for transfusion when allo- or autoantibodies preclude the use of conventional crossmatching techniques. A technique for labeling small volumes of donor red blood cells with [113mIn]tropolone is reported. The use of 113mIn minimizes the accumulation of background radioactivity and the radiation dose especially so when multiple crossmatches are performed. Labeling red cells with [113mIn]tropolone is faster and easier to perform than with other radionuclides. Consistently high labeling efficiencies are obtained and minimal 113mIn activity elutes from the labeled red blood cells. A case study involving 22 crossmatches is presented to demonstrate the technique. The radiation dose equivalent from 113mIn is significantly less than with other radionuclides that may be used to label red cells.

Hepatic uptake of technetium-99m HM-PAO in a fetus.

The normal biodistribution of technetium-99m HM-PAO ([99mTc]HM-PAO) includes significant uptake in the brain, liver, and kidneys. A pregnant patient studied with [99mTc] HM-PAO to confirm brain death provided an opportunity to examine the transplacental distribution of this radio-pharmaceutical in the unborn fetus. Uptake in the fetus after transplacental delivery is almost exclusively hepatic with a small amount of biliary excretion.

FDG PET of recurrent or metastatic 131I-negative papillary thyroid carcinoma.

UNLABELLED: This study reports on the use of FDG PET in the follow-up of papillary thyroid cancer patients with negative findings on 131I total body scans and elevated levels of thyroglobulin after total thyroidectomy. METHODS: Eleven asymptomatic patients with previous papillary thyroid cancer, total thyroidectomy, 131I ablation, and treatment of all known metastases had negative findings on 131I total body scans after therapy but persisting elevations of thyroglobulin when not receiving thyroid hormone. All imaging before PET failed to show persisting tumor. FDG PET was performed on all patients while receiving full thyroid hormone replacement, except for the repeated scan of 1 patient (patient 6). After the PET scan, all patients were referred for supplementary CT, sonography, or biopsy of lesions in the neck. RESULTS: All 11 patients showed FDG uptake in the neck or upper mediastinum-in the initial scan in 10 and in a repeated scan in 1. Sonographically guided biopsy confirmed malignancy in 6, was nondiagnostic in 2, and showed normal findings in 1. In 2 patients, the sonographic results were normal and no biopsy was attempted. FDG imaging redirected the treatment of 7 patients, resulting in surgery and external beam radiotherapy in 3, surgery in 1, and external beam radiotherapy in 2. One patient declined further recommended surgery. The other 4 patients remain under observation. Surgical histopathology confirmed thyroid tumor in all 4 surgically treated patients. Retrospective review of the original histopathology slides showed no preponderance of aggressive histology. CONCLUSION: FDG PET is able to guide further evaluation of thyroid cancer patients who have elevated thyroglobulin levels and normal findings on 131I whole-body scanning.

Diagnostic accuracy and pitfalls of [iodine-131]6-beta-iodomethyl-19-norcholesterol (NP-59) imaging.

NP-59 concentrates in steroid hormone synthesizing tissues, enabling scintigraphic localization and characterization of endocrine dysfunction in the adrenal cortex and ovary. Studying 108 consecutive cases from 1982 to 1985 and using clinical, biochemical, radiographic, and pathologic data, we performed a rigorous assessment of the accuracy and pitfalls of NP-59 scintigraphy. The evaluation was divided into categories of abnormal hormone secretion: Cushing's syndrome, primary aldosteronism, and hyperandrogenism. Additional categories included euadrenal tumors (without detectable hormone dysfunction) and sites of residual adrenal cortical tissue. The accuracy of NP-59 scintigraphy ranged from 71% in primary aldosteronism and 75% in euadrenal tumors, to 100% for Cushing's syndrome and hyperandrogenism. However, more than in most nuclear medicine studies, NP-59 imaging requires well-defined indications to be met for it to be efficacious, including the fulfillment of clear clinical, biochemical, and radiographic criteria. The high reproducibility of NP-59 scintigraphic interpretation was demonstrated when 40 random cases underwent interinstitutional exchange and through interobserver evaluation at the University of Michigan. Responses of 85/126 medical centers to questionnaires revealed the high level of NP-59 safety.

Cerebral perfusion imaging with technetium-99m HM-PAO in brain death and severe central nervous system injury.

We performed 38 cerebral perfusion studies in 33 patients with brain death or with severe central nervous system injury using technetium-99m hexamethyl-propyleneamine oxime [( 99mTc]HM-PAO). Uptake by the cerebrum and/or cerebellium was present in all patients who were not clinically brain dead (ten studies) although the study was often abnormal. In those patients who were brain dead, 16/17 studies demonstrated no uptake in either the cerebrum or cerebellum. In patients suspected of brain death, but who had conditions interfering with the diagnosis the test demonstrated no uptake in 9/11 studies, confirming brain death. A radionuclide angiogram (RNA) of the head was also performed in 33/38 studies and showed complete agreement with the [99mTc]HM-PAO uptake, except in one case. We conclude that cerebral perfusion imaging with [99mTc]HM-PAO is a simple, noninvasive and reliable test to confirm brain death. By comparison with conventional technetium agents, [99mTc]HM-PAO is not dependent on the quality of the bolus injection, is easier to interpret and allows evaluation of posterior fossa blood flow.

Frequency of myocardial injury after blunt chest trauma as evaluated by radionuclide angiography.

Seventy-seven patients who had sustained multisystem trauma, including severe blunt chest injury, were prospectively evaluated to assess the frequency of associated traumatic myocardial injury. Traumatic injury to either the right or left ventricle was defined by the presence of discrete abnormalities of wall motion on electrocardiographically gated cardiac scintigraphy in patients without a clinical history of heart disease. Forty-two patients (55%) (Group 1) had focal abnormalities of wall motion; 27 involved the right ventricle, 7 the left ventricle, 7 were biventricular, and 1 involved only the septum. Both the right and left ventricular ejection fractions were significantly (p less than 0.01) lower (31 +/- 11% and 47 +/- 14%, respectively) than those in the 35 traumatized patients without wall motion abnormalities on scintigraphy (Group 2) (49 +/- 8% and 58 +/- 11%, respectively). Repeat scintigraphic examination in 32 Group 1 patients at a time remote from initial injury showed improvement or resolution of previously defined focal wall motion abnormalities in 27 of 32 patients (84%). The electrocardiogram and serum enzyme tests were insensitive indexes of traumatic myocardial injury when defined by the scintigraphic abnormalities. Thus, severe blunt chest trauma results in a higher frequency of traumatic myocardial injury than heretofore recognized, and frequently involves the anteriorly situated right ventricle.

Hemodynamic adaptation to acute myocardial contusion complicating blunt chest injury.

The immediate hemodynamic sequelae of blunt chest injury complicated by acute myocardial contusion were examined in multiply traumatized patients. Focal defects of ventricular wall motion defined by gated cardiac scintigraphy identified acute myocardial contusion in 28 of 43 patients, involving the right ventricle alone in 18 (group 1A), the left ventricle in 4 (group 1B) and both ventricles in 6 (group 1C). Qualitatively normal ventricular wall motion was found in the 15 patients (group 2). Although there was no difference between groups 1A and 2 in mean systemic oxygen transport (620 +/- 189 vs 627 +/- 105 ml/min/m2), left ventricular ejection fraction (52 +/- 14% vs 60 +/- 9%) or calculated left ventricular end-diastolic and end-diastolic and end-systolic volumes, mean right ventricular (RV) ejection fraction was significantly lower in group 1A (29 +/- 9%) than in group 2 (47 +/- 7%, p less than 0.01). Concomitantly, evidence of RV systolic dysfunction was ml/m2) but not in group 2 (RV end-systolic volume, 50 +/- 21 ml/m2, p less than 0.05). RV stroke work was similar between the groups, and RV pump function was identical by virtue of a larger RV preload in group 1A (RV end-diastolic volume 143 +/- 63 ml/m2) than in group 2 (RV end-diastolic volume 93 +/- 26 ml/m2, p less than 0.05). Thus, use of the RV Frank-Starling mechanism in patients with traumatic RV contusion maintains RV pump function at a level similar to that in traumatized patients without acute myocardial contusion.