Status of F-18 fluorodeoxyglucose uptake in normal and hibernating myocardium after glucose and insulin loading

Objective

F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) has been increasingly used in myocardial viability imaging. In routine PET viability studies, oral glucose and intravenous insulin loading is commonly utilized. In an optimal study, glucose and insulin loading is expected to cause FDG uptake both in hibernating and normal myocardium. However, in routine studies it is not uncommon to see absent or reduced FDG uptake in normal myocardium. In this retrospective study we further analyzed our PET viability images to evaluate FDG uptake status in myocardium under the oral glucose and intravenous insulin loading protocol that we use in our hospital.

Methods

Patients who had both myocardial perfusion single photon emission computed tomography (SPECT) and FDG PET cardiac viability studies were selected for analysis. FDG uptake status in normal and abnormal myocardial segments on perfusion SPECT was evaluated. Based on SPECT and PET findings, patients were divided into two main groups and four subgroups. Group 1 included PET viable studies and Group 2 included PET-nonviable studies. Subgroups based on FDG uptake in normal myocardium were 1a and 2a (normal uptake) and 1b and 2b (absent or significantly reduced uptake).

Results

Seventy-one patients met the inclusion criteria. Forty-two patients were PET-viable and 29 were PET-nonviable. In 33 of 71 patients (46.4%) there was absent or significantly reduced FDG uptake in one or more normal myocardial segments, which was identified more in PET-viable than PET-nonviable patients (59.5% vs. 27.5%, p = 0.008). This finding was also more frequent in diabetic than nondiabetic patients (53% vs. 31.8%), but the difference was not significant (p = 0.160).

Conclusions

In nearly half of our patients, one or more normal myocardial segments showed absent or significantly reduced FDG uptake. This finding, particularly if it is diffuse, could be from suboptimal study, inadequacy of current glucose and insulin loading protocols, or various other patient-related causes affecting FDG uptake both in the normal and hibernating myocardium. In cases with significantly reduced FDG uptake in normal myocardium, PET images should be interpreted cautiously to prevent false-negative results for viability.

Chronic Recurrent Multifocal Osteomyelitis in Children: A Multidisciplinary Approach is needed to establish a Diagnosis

Chronic recurrent multifocal osteomyelitis (CRMO) is an inflammatory disease of unknown cause. In general, CRMO follows a characteristic clinical course and is regarded at present as a distinct entity. It affects bone and occurs predominantly in children and adolescents. The clinical, radiologic and pathologic findings are non-specific. The recognition of this rare entity is often delayed and difficulties in patient management sometimes emerge from its usual protracted course. We present a 6-year-old girl diagnosed with CRMO involving tibia and lumbar vertebra where a multidisciplinary approach was essential in making the diagnosis.

(99m)Tc-MIBI Whole Body Scan: A Potentially Useful Technique for Evaluating Metabolic Bone Disease

Metabolic bone disease due to hyperparathyroidism is characterized by increased bone resorption and new bone formation. ^99mTc- hexakis-2-methoxyisobutylisonitrile (^99mTc MIBI) accumulation is controlled by metabolic function and cell viability. To investigate, for the first time, the potential of whole body ^99mTc MIBI scan for detecting, visually and with the aid of quantitative analysis, bony changes associated with hyperparathyroidism. Eighty-six patients with hyperparathyroidism, referred routinely for parathyroid localization, were included in this case-control prospective study. Each patient was injected with 20-25 mCi of ^99mTc MIBI. Routine anterior cervico-thoracic images were obtained for parathyroid localization. Two extra whole body images were acquired and assessed visually and by drawing regions of interest over the mandible, sternum, femur, humeri, spine, and the soft tissue adjacent to the bone. The ratios of bone to soft tissue were calculated and compared to ratios drawn in a control group routinely referred for cardiac imaging and injected with ^99mTc MIBI, after confirming the absence of any bone disease. The visual interpretation of the scans showed 48 patients to have increased bone uptake. Quantitative assessment showed significant difference between the mean ratios of the case and control groups. The Kruskal-Wallis test showed significant agreement between visual and quantitative ratios drawn from delayed right and left femora and left humerus images (P < 0.05). ^99mTc MIBI whole body imaging is a potentially useful technique for assessing metabolic bone disease associated with hyperparathyroidism. Quantitative analysis helped in confirming the visual findings.

Horizons in nuclear medicine and molecular imaging: highlights of the Third Gulf Nuclear Medicine Conference

The Third Gulf Nuclear Medicine Conference took place in the state of Kuwait at Salwa Al Sabah hall, Safir marina hotel in Salmiya. The event extended from March 29th to April 1st 2009. The assembly was a great chance for all nuclear medicine, i.e. physicians, technologists and researchers in the field to meet and exchange experience and knowledge. The number of participators registered for this conference was beyond expectations; total registrants of 611 attended the event and actively end it. The conference was attended by international, regional and local participants. There were 23 speakers, including 13 invited guest speakers who came from USA, Canada, Europe and the Gulf region. In addition to the lectures and oral presentations, there were 30 poster presentations. The latest updates in the field together with most recent findings in the participants' own research were presented. The lectures and posters covered different basic and clinical categories of nuclear medicine. This article summarizes the highlights of the major topics discussed with some recommendations when applicable. Proceedings of the conference can be found in the World Journal of Nuclear Medicine of April, 2009.

Metastatic bone disease: evaluation by functional imaging in correlation with morphologic modalities

The diagnosis of presence, location and load of metastatic, bone involvement has important implication on patient management and prognosis. This requires collection of data obtained using different imaging modalities. Bone scintigraphy is a highly sensitive and cost-effective screening modality. However, to overcome its lower specificity and its limitation in evaluation of vertebral metastases, CT, PET or MRI can be utilized to verify the nature of suspicious lesions. Expansion of SPECT/ CT may fine tune the highly sensitive bone scintigraphy. PET has an emerging and leading role in many tumors, occasionally obviating the need for bone scintigraphy, particularly in evaluation of response to therapy. PET and whole body MRI offers a potentially important tool to provide the earliest clue of bone marrow metastasis. The value of F-18 PET as a sensitive bone imaging tool needs to be further evaluated on a larger scale in different setting including treated and untreated cancer patients and to evaluate also whether potentially better resolution would lead to more benign lesions detection mimicking metastasis such as fractures, inflammatory, infection, and degenerative involvement of bone. The added value of PET-CT is also to be further examined with this regard.

Multifocal post-traumatic scintigraphic changes mimicking bone metastases in a battered adult

Several pathologies have been reported to cause scintigraphic patterns similar to multiple bony metastases. Heterotopic bone formation is known to mimic several inflammatory and neoplastic conditions including recurrent tumors. However, no reports on multifocal heterotopic bone formation simulating the typical pattern of randomly distributed foci of increased uptake of metastases on bone scan were found in literature. We present a case of a young adult who was repeatedly assaulted by others over a period of one month and on bone scan had a pattern similar to bony metastasis due to multiple foci of heterotopic bone formation and fractures.

Role of positron emission tomography (PET) in the management of lymphoma

PET enhances staging of lymphoma and is superior to CT scan. It consequently provides more accurate basis for treatment regimens. It provides a better assessment of response to therapy and is the most useful non-invasive modality to differentiate residual tumor from fibrosis/necrosis. Persistent uptake during and after chemotherapy appear to have a high sensitivity in predicting subsequent relapse although some patients may remain in prolonged remission. A negative finding after therapy indicates a very favorable prognosis. We still need better refinement to set off patients who could really benefit from the additional information and better definition of the optimal timing of imaging in clinical practice, The use of early PET response in determining choice of therapy should be utilized with caution until some critical questions are answered. These include: When is the best time to use PET for response assessment? what is the most suitable methodology, visual or quantitative? can early responders be cured with less intensive therapy? will survival be better for patients treated more intensively because they have a poor interim metabolic response?. Further evaluation of alternative PET radiotracers and whether they are superior to FDG and evaluation of the added value of dual FDG-PET acquisition are needed. When PET is not available, Ga-67 imaging of lymphoma can also provide information regarding the presence or absence of active lymphoma particularly in assessing the response to therapy and predicting the outcome.

Synergistic effects of ethanol and hyperthermia on carotid artery vasoconstriction

BACKGROUND

Heatstroke is a serious condition and clinical studies indicate that vascular stroke increases with excessive consumption of alcohol (ethanol). It was our objective to test the influence of ethanol on cerebral perfusion at normal and higher temperatures.

METHODS

Recording of isometric tension in rabbit carotid artery strips in organ baths with different concentrations of ethanol at 37 degrees C and during hyperthermia (39-43 degrees C) and scintigraphic cerebral imaging of a radioactive isotope in the control situation and during hyperthermia.

RESULTS

Stepwise heating induced reproducible reversible graded contraction, proportional to temperature. At high concentrations (toxic levels), ethanol induced an increase in tension and heating potentiated these responses. Extracellular Mg(2+) potentiated both heat-induced contraction and ethanol-induced contraction while extracellular Ca(2+) had no effect on these responses. During hyperthermia and ethanol scintigraphic isotope uptake was reduced in cortical and cerebellar regions.

CONCLUSIONS

Carotid artery vasomotor tone is temperature dependent and heating induces vasoconstriction. Alcohol (ethanol) at 37 degrees C elicited carotid artery contraction at high concentrations (toxic levels) but at any concentration during elevated temperature (39-43 degrees C). Ethanol potentiated the effect of hyperthermia-induced vasoconstriction and reduced cerebral perfusion as shown by radionuclide imaging. The synergistic effect of ethanol and hyperthermia may induce heat stroke and brain damage.

Impact of operator on determining functional parameters of nuclear medicine procedures

OBJECTIVE

The study was designed to assess the significance of the interoperator variability in the estimation of functional parameters for four nuclear medicine procedures.

MATERIALS AND METHODS

Three nuclear medicine technologists with varying years of experience processed the following randomly selected 20 cases with diverse functions of each study type: renography, renal cortical scans, myocardial perfusion gated single-photon emission computed tomography (MP-GSPECT) and gated blood pool ventriculography (GBPV). The technologists used the same standard processing routines and were blinded to the results of each other. The means of the values and the means of differences calculated case by case were statistically analyzed by one-way ANOVA. The values were further analyzed using Pearson correlation.

RESULTS

The range of the mean values and standard deviation of relative renal function obtained by the three technologists were 50.65 +/- 3.9 to 50.92 +/- 4.4% for renography, 51.43 +/- 8.4 to 51.55 +/- 8.8% for renal cortical scans, 57.40 +/- 14.3 to 58.30 +/- 14.9% for left ventricular ejection fraction from MP-GSPECT and 54.80 +/- 12.8 to 55.10 +/- 13.1% for GBPV. The difference was not statistically significant, p > 0.9. The values showed a high correlation of more than 0.95. Calculated case by case, the mean of differences +/- SD was found to range from 0.42 +/- 0.36% in renal cortical scans to 1.35 +/- 0.87% in MP-GSPECT with a maximum difference of 4.00%. The difference was not statistically significant, p > 0.19.

CONCLUSION

The estimated functional parameters were reproducible and operator independent as long as the standard processing instructions were followed.

Skeletal imaging of Gorlin's syndrome

OBJECTIVE

To report a case of a patient with many of the common manifestations of Gorlin's syndrome, a rare inherited condition.

CLINICAL PRESENTATION AND INTERVENTION

A 26-year-old female with longstanding left hip pain was referred for bone scintigraphy to find the cause of pain. The findings on bone scintigraphy as well as prior radiographic studies illustrated many of the defining features of Gorlin's syndrome, i.e. jaw keratocysts, falcine calcifications, short and deformed ribs, Sprengel deformity and a sclerotic bone lesion. The past medical history also revealed dermatologic, cardiac and gynecological findings related to the syndrome.

CONCLUSION

Our case highlights the multisystemic involvement of Gorlin's syndrome, based particularly on the skeletal findings. Practicing physicians, including imaging specialists, should be familiar with these findings to reach the diagnosis.

The effect of intermittent pneumatic compression on the bone uptake of (99m)Tc-labelled methylene diphosphonate in the lower limb

INTRODUCTION

Venous compression of the lower limbs will obstruct outflow through the deep and superficial veins, yet inflow will continue, without continual swelling of the limb. It is hypothesised that venous channels in the long bones act as collateral channels to restore outflow, and therefore general blood flow through bone will increase. Such a hemodynamic change should affect the uptake of radiopharmaceuticals by the bone, though uptake changes in themselves would not definitely indicate flow changes. The purpose of this study, therefore, was to determine whether bone uptake in the lower limb is affected by intermittent venous compression, irrespective of the mechanism involved.

MATERIALS AND METHODS

The effect of intermittent pneumatic compression of the thigh and calf on the uptake of (99m)Tc-methylene diphosphonate (MDP) was studied in 24 patients. All were undergoing routine bone imaging for medical conditions that were not focused on their lower limbs, and received 1 h of the therapy at 60 mmHg on one limb only, after injection of the radiopharmaceutical. Three hours after injection the relative difference in uptake (net counts per pixel) between the two limbs was calculated. The standard imaging protocol was otherwise unchanged.

RESULTS

The median differences in uptake in the intermittently compressed limb compared with the contralateral limb were +7.6% (interquartile range +3.9% to +16.0%, p<0.0005 [Wilcoxon]) for the anterior aspect of the femur; +11.7% (interquartile range +4.3% to +22.2%, p<0.0005) posterior, femur; +10.5% (interquartile range +6.5% to +13.8%, p<0.0005) anterior, tibia; +10.6% (interquartile range +5.5% to +17.6%, p<0.0005) posterior, tibia.

CONCLUSION

Intermittent pneumatic compression clearly and significantly increased the uptake of (99m)Tc-MDP in long bones. These data are consistent with increases in blood flow through bone, though a direct mechanical influence on the bone cannot be excluded. This effect should be given consideration during routine therapeutic and thromboprophylactic use of intermittent compression, and if the mechanism of the uptake changes can be established, their possible clinical uses should be investigated.

Tc-99m DMSA renal scan in first-time versus recurrent urinary tract infection-yield and patterns of abnormalities

PURPOSE

To determine the yield and patterns of abnormalities noted by Tc-99m DMSA renal imaging in cases of first-time versus recurrent urinary tract infections (UTIs) in children.

MATERIALS AND METHODS

We reviewed 101 Tc-99m DMSA studies performed for 52 first-time and 49 recurrent UTIs in 99 children during a period of 1 year. The average age of the patients was 4.4 years, and the female:male ratio was 7:1. Static images of the kidneys were acquired 2 hours after injection of Tc-99m DMSA in anterior, posterior, and right and left posterior oblique views. SPECT was performed in 9% of the cases. The studies were scored as normal or abnormal.

RESULTS

The yield of abnormal scans in first-time UTIs was 22 (42%) and in recurrent UTI 27 (55%). Three categories of abnormalities were noted: 1) renal cortical defects (55% of the abnormal scans in first-time UTIs and 59% of the abnormal scans in recurrent UTIs; P = 0.40); 2) dilated pelvicalyceal system (27% of the abnormal studies in first-time UTIs and 63% of the abnormal studies in recurrent UTIs; P < 0.01); and 3) renal swelling showing disproportionate function with size (41% of the abnormal scans in first-time UTIs and 22% of the abnormal scans in recurrent UTIs; P = 0.21).

CONCLUSIONS

The high yield of renal abnormalities by Tc-99m DMSA scanning emphasizes the importance of testing all cases of UTI, including patients with a first-time infection. Documentation of the pattern of abnormalities may help in planning for subsequent management of UTIs in these patients.

Cyclic cystography: diagnostic yield in selected pediatric populations

PURPOSE

To test the hypothesis that the diagnostic yield of cyclic cystography is related to the prevalence of vesicoureteral reflux (VUR) in the population being evaluated.

MATERIALS AND METHODS

Two groups of children were examined prospectively: 124 with severe urinary tract infection, defined as patient hospitalization or a maximum temperature greater than 39.5 degrees C, and 135 with previously diagnosed VUR. Nuclear cystography was performed in 249 patients, and fluoroscopic cystography was performed in 10. If VUR was not seen during the first cycle of bladder filling and voiding, a second cycle was performed.

RESULTS

VUR was present during cycle 1 in 40 (32%) of 124 patients with severe urinary tract infection and 90 (67%) of 135 children in the VUR follow-up group (P < .001). VUR was demonstrated during cycle 2 in seven (9%) of 76 of the severe urinary tract infection group and eight (24%) of 34 of the VUR follow-up group (P = .045). Of 15 patients with VUR during cycle 2, two had grade III VUR and 13 had grade I or II VUR.

CONCLUSION

The second cycle of cyclic cystography has a higher diagnostic yield in patients undergoing VUR follow-up than in patients with severe urinary tract infection. The decision to perform a second cycle of bladder filling and voiding should take into account the pretest probability of VUR in the child being examined.

A new experimental model for partial ureteric obstruction in sheep

This study aimed to develop a new experimental model of partial ureteric obstruction in sheep. Graded obstruction of the ureter using various sized catheters (Fr 3-8) for variable durations up to 6 weeks was performed in 19 sheep. The kidneys were studied by radionuclide diuretic renography for up to 21 weeks and had histopathological examination at the end of the experiment. Catheters of Fr 3 or Fr 5 should be used to block the ureter for a minimum of three weeks to produce sufficient functional and pathological changes to be studied. The advantages and disadvantages of this model are discussed.

Assessment of 99Tcm-tetrofosmin lung uptake: a modified method to avoid the contribution from high chest wall activity

Evaluation of lung uptake during routine 99Tcm-tetrofosmin myocardial SPET (single photon emission tomography) studies may be hindered by substantial chest muscle uptake, particularly post-exercise. This study investigated this proposal and analysed the various components of chest activity that may add to the real lung uptake. Exercise SPET studies were performed on normal subjects using 99Tcm-tetrofosmin and compared with the results of 99Tcm-sestamibi and 201Tl studies. The chest to heart count ratio (CHR) was calculated from the anterior SPET projection and further subclassified into lung, anterior chest and posterior chest to heart ratios (LHR, AHR, PHR) from the left anterior oblique (LAO) projection. On post-exercise images, the 99Tcm-tetrofosmin CHR was significantly higher than that of 201Tl and 99Tcm-sestamibi. Both the 99Tcm-tetrofosmin AHR and PHR were higher than those of 201Tl and 99Tcm-sestamibi. However, the LHR was similar for all three radiopharmaceuticals. In contrast, the rest 99Tcm-tetrofosmin images differed little from the 201Tl and 99Tcm-sestamibi ones. Thus, 99Tcm-tetrofosmin lung uptake post-exercise should be interpreted with caution, as chest muscle uptake is higher than normal. A more accurate evaluation of 99Tcm-tetrofosmin lung uptake is achieved from the LAO projection, where the contribution from chest muscle counts is much less than in the routinely used anterior projection.

Imaging of infection: a correlative and algorithmic approach

Detection and localization of infection can still be a dilemma for both clinicians and imaging specialists. The list of morphologic and physiologic modalities is increasing with the advancement of research, expanding the applications of existing modalities and developing new radiopharmaceuticals for infection imaging.Since no single modality is appropriate for all situations, imaging strategy for the diagnosis of infection in both soft tissue and bone should be tailored for individual patients according to the detailed clinical data including the history of underlying and previous disease processes and the site of suspected infection for proper and cost effective utilization of the different imaging modalities.

Impact of bone scintigraphy on the clinical management of a patient with sickle cell anemia and recent chest pain

The authors present a cases of acute chest syndrome that was originally thought to be due to pneumonia, in which bone imaging obtained 4 weeks later for knee pain showed a secondary finding of multiple rib infarcts that clarified the etiology of the patient's chest manifestations and led to a change in the management of the patient. Bone scintigraphy should be considered in the work-up of patients with sickle cell anemia and concurrent chest symptoms.

Indium-111-leukocyte and technetium-99m-sulfur colloid uptake in Paget's disease

We report a case of polyostotic Paget's disease of bone that caused an unusual pattern of accumulation of 111In leukocytes that mimicked, at some sites, uptake of osteomyelitis, which was suspected in this patient. Technetium-99-m sulfur colloid scan clarified the nature of 111In-leukocyte accumulation as secondary to expanded active bone marrow uptake in some pagetic bones. Additionally, a spectrum of 111In-leukocyte and 99mTc-sulfur colloid uptake was noted in the bones involved by the disease that represented uptake by pagetic foci at different pathologic phases of disease. This case suggests that Paget's disease should be considered as a diagnostic possibility for areas of 111In-leukocyte accumulation, particularly when expanded uptake is seen. When suspected, correlation with bone marrow scan and/or standard radiographs should be obtained. Recognizing that Paget's disease can not only cause absent but also expanded bone marrow (depending on the disease stage) and consequently abnormal 111In-leukocyte uptake, should help avoid interpretational confusion.

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.