High-resolution multi-detector SPET imaging of the paediatric spine

We reviewed the planar and single photon emission tomographic (SPET) spine images of 69 paediatric patients aged 2-17 years referred for undiagnosed back pain. The SPET images were obtained using a triple-detector camera and ultra-high-resolution collimation. Abnormal images were rated as slightly positive (1+) or strongly positive (2+). The planar and SPET images were normal in 48 of 69 patients. Thirteen of the remaining 21 cases had negative planar imaging with positive SPET images (SPET was 2+ in 10 cases and 1+ in 3 cases). Four of the 21 cases were 1+ on planar imaging, but clearly positive (2+) on the SPET images. Three of the 21 cases had 2+ planar abnormalities, but SPET demonstrated additional uptake abnormalities. Lastly, a single case that was 2+ on the planar images was demonstrated to be artefactual by SPET. Thirty-seven sites were abnormal by SPET, including 17 pedicle/parts interarticularis (11 patients), 10 spinous process (8 patients), 8 vertebral endplate (2 patients) and 2 vertebral body (2 patients) abnormalities. Sites that were abnormal on SPET and normal on planar imaging included 10 of 17 (59%) in the pedicle/pars region, 9 of 10 (90%) in the spinous process, 1 of 2 (50%) in the vertebral body and 2 of 8 (25%) in the vertebral endplates. The improved resolution of ultra-high-resolution collimated multi-detector SPET permits visualization of a greater variety of abnormalities than was seen with earlier single-detector cameras, particularly those involving the spinous process.

Heterotopic ossification mimicking infection. Scintigraphic evaluation

Heterotopic ossification is a disorder of unknown etiology characterized by bone formation in the mesenchymal tissues. It occurs most commonly in patients who have had traumatic brain injury, spinal cord injury, or joint trauma or surgery.

Multimodality imaging of osteomyelitis

Early diagnosis of osteomyelitis continues to be a clinical problem. Multiple imaging modalities are being used for the diagnosis of osteomyelitis, but none of them is ideal for all cases. The choice of modality depends on several factors based on an understanding of the pathophysiologic aspects of different forms of osteomyelitis. After a brief introduction outlining some basic principles regarding the diagnosis of osteomyelitis, pathophysiologic aspects are reviewed. Advantages and disadvantages of each imaging modality and their applications in different forms of osteomyelitis are discussed. The use of different imaging modalities in the diagnosis of special forms of osteomyelitis, including chronic, diabetic foot, and vertebral osteomyelitis, and osteomyelitis associated with orthopedic appliances and sickle cell disease is reviewed. Taking into account the site of suspected osteomyelitis and the presence or absence of underlying pathologic changes and their nature, an algorithm summarizing the use of various imaging modalities in the diagnosis of osteomyelitis is presented.

Advanced fibrodysplasia ossificans progressiva

Fibrodysplasia ossificans progressiva is a rare hereditary variant of heterotropic bone formation that is often difficult to diagnose. A bone scan of an advanced case of this condition is presented. Nuclear medicine physicians should be familiar with various aspects of this disease.

Scintigraphic evaluation of pancreatic transplants using technetium-99m-sestamibi

The purpose of this study was to evaluate the feasibility of using 99mTc-sestamibi in the assessment of pancreatic transplant.

METHODS

Ten transplant recipients with a history of insulin-dependent diabetes mellitus were studied. Fourteen 99mTc-sestamibi studies were performed. Each patient was injected intravenously with 10 mCi of 99mTc-sestamibi. Two-second frames were obtained for 1 min, followed by serial dynamic and static images every 5 min for 30 min. Technetium-99m sestamibi studies, read by two nuclear medicine physicians, were correlated with clinicopathologic findings and compared to the ten 201Tl studies obtained in seven of these patients.

RESULTS

On 99mTc-sestamibi images, normally functioning grafts showed adequate perfusion on the angiogram and good uptake followed by clearance on static images. Time-activity curves showed an initial upslope followed by a downslope after the initial uptake peak. The quality of 99mTc-sestamibi images was superior to those of 201Tl in five, similar in four and marginally inferior in one paired study. Technetium-99m-sestamibi was used for both flow and static images, whereas a 99mTc radiotracer angiogram was needed to accompany the 201Tl study.

CONCLUSION

Our preliminary experience indicates that 99mTc-sestamibi helps evaluate pancreatic transplants and provides high count statistics, which result in better image quality and diagnostic detail. Extensive quantitative studies are being performed to further evaluate this agent's role in the clinical management of pancreatic transplant patients.

A comparative study between planar Ga-67, Tl-201 images, chest x-ray, and x-ray CT in inoperable non-small cell carcinoma of the lung

Seventy patients with newly diagnosed, pathologically proven inoperable non-small cell lung cancer (NSCLC) had planar Ga-67, Tl-201, chest x-ray, and chest CT imaging performed. Tumor/Normal tissue background (T/B) ratio was calculated for 62 Ga-67 and 55 Tl-201 scintigraphy studies and comparisons were made between Ga-67 and Tl-201 imaging results regarding T/B ratios, site of lesion, and histologic type. The impact of the images on the initial knowledge of the extent of the tumor and on the radiotherapy (RT) planning was evaluated for each patient. For primary lesions, Ga-67 imaging results were positive in 94% (66 of 70 patients) versus 71% (50 of 70 patients) for Tl-201 scans (P < 0.005) and the T/B ratio was > 1.5 in 74% (46 of 62 patients) for Ga-67 versus 36% (20 of 55 patients) for Tl-201 (P < 0.0001). For centrally located lesions, sensitivity for Ga-67 was 100% (53 of 53 patients) versus 74% (39 of 53 patients) for Tl-201 (P < 0.0005) and the T/B ratio > 1.5 in 84% (38 of 45 patients) for Ga-67 versus 38% (15 of 40 patients) for Tl-201 (P > 0.001). For peripheral lesions, sensitivity of Ga-67 was 76% (13 of 17 patients) versus 64% (11 of 17) for Tl-201 (P > 0.05) and the T/B ratio was > 1.5 in 47% (8 of 17 patients) for Ga-67 versus 33% (5 of 15 patients) for Tl-201 (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Iodine-131 therapy of hyperthyroidism in pediatric patients

The purpose of this retrospective study was to evaluate the utility of 131I as therapy for hyperthyroidism in children and to evaluate its short-term side effects.

METHODS

The results of 131I therapy of hyperthyroidism were evaluated in a group of 35 pediatric patients.

RESULTS

In 29 patients propylthiouracil or methimazole therapy was abandoned due to noncompliance (13), relapse or failure to control hyperthyroidism (13), vasculitis (1), neutropenia (1) or a lupus-like syndrome (1). Average treatment activity was 7.7 +/- 2.9 (s.d.) mCi, corresponding to 0.16 +/- 0.03 mCi/g. Thirty patients (86%) received a single radioiodine treatment and five (14%) were retreated. In patients who became hypothyroid after a single dose, hypothyroidism was noted within 100 days of treatment. Clinical management problems included vomiting in four patients and enuresis in four patients. Mild radiation thyroiditis occurred in one patient and nodularity was noted after therapy in two patients.

CONCLUSION

Iodine-131 is effective for both initial treatment of hyperthyroidism and the treatment of medical treatment failures in pediatric patients. Awareness of vomiting and enuresis as potential management problems is crucial when using 131I in this age group. Therefore, special treatment precautions may be required.

Diffuse Tl-201 uptake in the lungs. Etiologic classification and pattern recognition

Diffuse Tl-201 uptake in the lungs could be because of cardiac, neoplastic, inflammatory, or interstitial lung disease. Examples from the different categories, differential diagnosis, and different patterns are presented. The authors discuss the different mechanisms of increased Tl-201 uptake in the lungs which vary according to the underlying pathology.

I-123 MIBG scintigraphy in adults. A report of clinical experience

Thirty-one adult patients with clinical findings suggestive of pheochromocytoma were studied with I-123 MIBG. All patients had images obtained at 24 and 48 hours. Five patients had abnormal uptake proved to be because of I-123 MIBG avid tumors. The remaining 26 patients had no proven tumors and showed physiologic uptake in various organs. The 24-hour images were of high quality. In all cases, the 48-hour images contributed no significant additional information. Only in 1 patient did the 48-hour image add some certainty. Physiologic uptake was seen in the salivary glands, liver, G.I. tract, and urinary bladder in all patients (100%). Uptake was also observed in the lung and heart (90%), normal adrenal glands (32%), thyroid (29%), spleen (23%) uterus (13%), and neck muscles (6%). The authors' experience indicates that I-123 MIBG gives superior images compared to the previously used I-131 MIBG, that the optimum imaging time for adults is 18-24 hours, and that normal distribution patterns including uterine and neck muscle uptake should be familiar to physicians interpreting the studies.

Positional biliary stasis: scintigraphic findings following biliary-enteric bypass surgery

Hepatobiliary scintigraphy has proven to be a reliable noninvasive imaging modality to evaluate postoperative biliary obstruction, which is a frequent complication following biliary enteric bypass surgery. We present a case of a patient who had biliary enteric bypass surgery with a scintigraphic pattern simulating partial obstruction on a 99mTc hepatobiliary study performed with the patient in a supine position. The biliary stasis seen in the supine images disappeared almost completely when the images were repeated after 30 min in an upright position. Progressive accumulation of activity initially seen in the region of the biliary enteric anastomosis was not present 3 days later on a repeat study with the patient in an upright position, confirming that biliary stasis in this patient was due to a positional phenomenon. This case illustrates that biliary stasis may be positional in nature. Position related stasis should be a consideration when interpreting hepatobiliary scintigraphic studies in postoperative patients and when suspected, patients should be imaged in the upright position.

Perfusion and ventilation scans in patients with extensive obstructive airway disease: utility of single-breath (washin) xenon-133

The presence of extensive obstructive airway disease in many patients leads to an interpretation of intermediate or indeterminate probability for pulmonary emboli using ventilation/perfusion lung scans. We observed that patients with extensive obstructive airway disease having perfusion abnormalities matching those on a single-breath xenon image usually have a normal pulmonary angiogram. This study's objective was to further assess the utility of a single-breath image in evaluating patients with extensive obstructive airway disease and abnormal perfusion studies categorized as having intermediate or indeterminate probability of pulmonary embolism in an attempt to decrease the number of nondiagnostic studies.

METHODS

We studied retrospectively 33 patients with extensive obstructive airway disease, with abnormal perfusion scans and no infiltrates on chest x-ray categorized as having intermediate or indeterminate probability of pulmonary embolism. We established the presence or absence of matching ventilation and perfusion abnormalities by comparing perfusion scan and single-breath images.

RESULTS

Among 25 patients with perfusion abnormalities matching the initial ventilation pattern on single-breath images, only 1 (4%) had pulmonary emboli as documented by pulmonary angiogram. Four out of the remaining 8 patients with no matching perfusion and single-breath ventilation pattern had pulmonary emboli (50%).

CONCLUSION

Patients categorized by ventilation/perfusion scintigraphy as having intermediate or indeterminate probability for pulmonary emboli due to the presence of extensive obstructive airway disease can be further subclassified using single-breath images. Patients with matching perfusion and single-breath ventilation pattern should be categorized as having low probability for pulmonary embolism, regardless of the extent of the ventilation abnormalities.

Iodine-123-MIBG SPECT versus planar imaging in children with neural crest tumors

Iodine-123-metaiodobenzylguanidine (MIBG) SPECT was compared with 123I-MIBG planar imaging in 35 studies of 25 children with neural crest tumors.

METHODS

Iodine-123-MIBG (0.070-0.140 mCi/kg intravenously) was followed at 24 hr by wholebody planar imaging and triple-detector, high-resolution thoraco-abdominal SPECT. At 48 hr, thoracoabdominal planar imaging was performed whenever a high-tissue background or gut activity interfered with the interpretation of the 24-hr planar images. SPECT views included a cine loop presentation of multiple volume-rendered projections. Two reviewers enumerated the number of abnormal sites on the planar and SPECT studies and rated the certainty of interpretation for each study on a scale from 0.1 (low certainty) to 1.0 (high).

RESULTS

Abnormal uptake was noted on planar or SPECT imaging in 13 studies (seven patients). The average number of abnormal sites detected per study for all 35 studies was 2.7 for planar imaging and 2.9 for SPECT (p = not significant) (and 7.2 and 8.4 for planar and SPECT, respectively, for the 13 abnormal studies.) The certainty ratings for all 35 studies were 0.74 for planar studies, 0.82 for SPECT (p = 0.05, chi-square, compared with planar) and 0.86 for planar and SPECT combined (p = 0.01 compared with planar alone). On volume-rendered images, gut activity was seen as diffuse and/or linear intraluminal activity.

CONCLUSION

When 123I-MIBG SPECT is used, the number of lesions detected is not increased, but there is a significant improvement in the certainty of interpretation over planar imaging.

Imaging modalities in the follow-up of non-iodine avid thyroid carcinoma

INTRODUCTION

The treatment of primary thyroid cancer requires protracted follow-up because of to the possibility of the development of recurrent metastases many years after the initial diagnosis. Often such follow-up involves imaging at regular intervals with diagnostic I-131 studies. However, not all thyroid cancer concentrates I-131. The purpose of this article is to review the efficacy of alternative diagnostic imaging modalities for follow-up of thyroid carcinomas that do not concentrate radioiodine.

MATERIALS AND METHODS

These procedures include the use of nuclear medicine imaging with thallium-201 (TI-201), Tc-99m-sestamibi, Tc-99m pentavalent dimercaptosuccinic acid (DMSA), radiolabeled anti-carcinoembryonic antigen antibodies, and radioiodinated-131 meta-iodobenzyl guanidine, as well as computerized x-ray tomography, magnetic resonance imaging (MRI), and ultrasound (US).

RESULTS AND CONCLUSION

Thallium-201, MRI, and pentavalent DMSA provide adequate sensitivity for follow-up of selected patients with suspected recurrent noniodine concentrating thyroid carcinoma.

Detection of protein bound vitamin B12 malabsorption. A case report and review of the literature

The Schilling test is used to identify the cause of vitamin B12 malabsorption in patients with low serum vitamin B12 levels. The initial step required for vitamin B12 absorption is a process of separation from the protein complexes of food. The crystalline Co-57 vitamin B12 used in the Schilling test does not reproduce this physiologic process. Thus, a crystalline stage I Schilling test may be normal even in the face of cobalamin malabsorption. An adjunctive stage I Schilling test using Co-57 vitamin B12 bound to protein has been developed. The authors describe a patient with protein-bound vitamin B12 malabsorption whose crystalline Co-57 vitamin B12 stage I Schilling test was normal. A subsequent stage I Schilling test using Co-57 vitamin B12 bound to chicken serum revealed significant cobalamin malabsorption. A review of the history and literature of this diagnostic test using protein bound vitamin B12 is also presented.

Comparison of technetium-99m-Q3 and thallium-201 for detection of coronary artery disease in humans

Technetium-99m-Q3 is a myocardial imaging agent that produces prompt myocardial visualization in humans.

METHODS

In 19 patients with angiographic coronary artery disease, 2 patients with no angiographic coronary artery stenosis greater than 50% of the luminal diameter and 6 healthy volunteers, exercise and resting myocardial imaging were performed with 99mTc-Q3 and also with 201Tl. Technetium-99m-Q3 imaging began 15 min after injection at rest and with exercise, in a complete imaging sequence that required less than 100 min.

RESULTS

Overall accuracy for coronary disease detection was 78% (21 true-positive or true-negative studies among 27 study participants) by tomographic thallium imaging versus 89% for 99mTc-Q3 tomographic imaging (p = ns). Accuracy for detection of individual coronary stenoses was 75% (61 true-positive or true-negative coronary segment classifications among 81 total coronary segments) for 201Tl imaging and 83% for 99mTc-Q3 imaging (p = ns).

CONCLUSIONS

Technetium-99m-Q3 when used in a rest-exercise sequence that can be completed in 100 min appears to provide comparable diagnostic accuracy to 201Tl for overall coronary disease detection and detection of individual coronary artery stenoses.

Neural crest tumors: I-123 MIBG imaging in children

PURPOSE

To determine 24- and 48-hour distribution of iodine-123 metaiodobenzylguanidine (MIBG) and to establish an optimized pediatric imaging protocol.

MATERIALS AND METHODS

Seventy-seven I-123 MIBG scans obtained in 33 children undergoing evaluation for neural crest tumor were reviewed.

RESULTS

Activity in the salivary glands, myocardium, liver, gut, and bladder was demonstrated on almost all scans. Activity was noted in the neck muscles, thyroid gland, and uninvolved adrenal gland in fewer studies. In 20 studies, abnormal uptake was present in the chest or abdomen at 24 and 48 hours, and lesion identification was improved at 48 hours in 12 studies. Detection of skeletal lesions on 14 scans was similar at 24 and 48 hours. Foci of tumor were first detected at I-123 MIBG imaging in nine studies, and in only two patients was tumor involvement initially missed on I-123 MIBG studies.

CONCLUSION

Distribution of I-123 MIBG on images in children differs from that in earlier descriptions in adults. Images of the torso at 48 hours after injection are a useful adjunct in detection of lesions.

Scintigraphic evaluation of duodenogastric reflux: significance in the diagnosis of acute cholecystitis

Duodenogastric reflux (DGR) as seen on hepatobiliary scintigraphy has been reported as a useful secondary sign for the diagnosis of acute cholecystitis. We evaluated the association of reflux with cases of acute cholecystitis as compared to those with chronic cholecystitis or other conditions. Thirty-six of 198 patients referred for hepatobiliary imaging showed DGR (18%). Among 26 patients with acute cholecystitis, 6 (23%) had DGR as compared to 9/40 (23%) cases with chronic cholecystitis, 3/12 cases with acute pancreatitis, 4/13 cases with previous cholecystectomy, and 3/8 cases with duodenal ulcer. No statistically significant differences were found between the prevalence of DGR in cases with acute cholecystitis and those with chronic cholecystitis or other nonacute cholecystitis diagnostic categories. Although acute cholecystitis is a condition frequently associated with DGR, such reflux is a nonspecific finding and should not be considered as a secondary sign of acute cholecystitis when interpreting hepatobiliary scans.

Phosphorus-32 radiopharmaceuticals for the treatment of painful osseous metastases

Phosphorus-32, employed as the orthophosphate or polyphosphate, can reduce or relieve the pain of osteoblastic metastases without serious hematologic toxicity, especially if used as a single injection. Uptake of this beta-emitter by osteoblastic-reactive bone and possibly by tumor and other cells can lead to pain reduction and often to cell killing. Efficacy has been demonstrated for the treatment of pain in 84% of 322 breast cancer patients and 77% of 444 prostate cancer patients found in a review of the literature. These results match those of the newer radiopharmaceuticals currently under investigation.

Silent obstruction after extracorporeal piezoelectric lithotripsy

Extracorporeal piezoelectric lithotripsy (EPL) is frequently used to treat renal calculi. We are presenting a case that developed silent ureteric obstruction following three sessions of EPL of 4,000 shocks each. The obstruction was silent and asymptomatic, and was detected 6 weeks later on a routine follow-up renogram. The obstruction was due to an impacted stone fragment in the lower ureter. After release of the obstruction, the kidney function did not return to pre-therapy levels due to irreversible damage. This case demonstrates the importance of doing renograms before and within a few days after shock therapy for renal stones.

Evaluation of renal functional changes after extracorporeal piezoelectric lithotripsy (EPL) by radionuclide studies

Extracorporeal piezoelectric lithotripsy (EPL) has been recently introduced as a non-invasive method for treatment of renal and gall bladder stones. Thirty seven patients treated with EPL for renal calculi were the subjects of radionuclide renal studies. The aim was to evaluate the effects of EPL as a new technology by radionuclide renography. 99Tcm-DTPA and 99Tcm-DMSA studies were performed pre-EPL and one day and one week post-EPL. Various parameters of the sequential radionuclide studies were evaluated. One day post-EPL, changes in parenchymal transit time index, relative uptake function, glomerular filtration rate, time-activity curves and kidney dimensions were observed. At one week post-EPL, different parameters returned to baseline status in the majority of cases. The study indicates that EPL has a variety of effects on the kidney that could be demonstrated and followed by sequential radionuclide renal studies. Furthermore the study suggests spacing of EPL sessions by approximately one week.