No firm association between N-terminal pro-brain natriuretic peptide and percentage of pulmonary vascular obstruction in patients with acute pulmonary embolism.

INTRODUCTION: High concentrations of N-terminal-pro-brain natriuretic peptide (NT-proBNP) are found in patients with right ventricular overload. Right ventricular overload may be the result of large perfusion defects in patients with pulmonary embolism (PE). NT-proBNP levels are associated with poorer outcome in patients with acute PE. Likewise, the percentage of pulmonary vascular obstruction (PVO) has shown to be a prognostic parameter for outcome in PE-patients. We postulated that NT-proBNP is associated with the amount of perfusion defects, expressed as the PVO, on perfusion scintigraphy. METHODS: We included 85 consecutive patients in whom the diagnosis PE was confirmed by ventilation-perfusion scintigraphy. PVO was calculated in all patients. NT-proBNP concentrations were measured at presentation. We plotted the logarithm of NT-proBNP versus the PVO. The strength of the estimated association between NT-proBNP and the PVO was expressed by R2. RESULTS: Eighteen percent of the variation in PVO could be explained by NT-proBNP. A positive association becomes apparent for NT-proBNP values above 200 pg/mL, with an increase in PVO of 6.3% (95% Confidence Interval 2.0 to 10.6), with every doubling of NT-proBNP. CONCLUSION: There is an association between NT-proBNP concentrations and PVO, although this relation is quite weak. Some patients with low NT-proBNP values can have a high PVO, which might be relevant for outcome. Therefore, we advise caution in risk stratification and not to focus on NT-proBNP, without involving the clinical condition.

Imaging the inflammatory activity of sarcoidosis: sensitivity and inter observer agreement of (67)Ga imaging and (18)F-FDG PET.

AIM: The aim of this study was to investigate sensitivity of 67Ga imaging and 18F-FDG PET for sarcoidosis activity and their inter observer variability. METHODS: Thirty-four newly diagnosed, histologically proven sarcoidosis patients were analyzed prospectively. (67)Ga imaging and (18)F-FDG PET were performed, the presence of pulmonary and extra pulmonary lesions was evaluated and inter observer variability of both techniques was assessed. RESULTS: Overall sensitivity to detect active sarcoidosis was 88% for (67)Ga imaging and 97% for (18)F-FDG PET. Although these results were not significantly different, 18F-FDG PET detected more lesions in the mediastinum (P<0.05), hila (P<0.05), lymph nodes (P<0.001) and extra pulmonary regions in general (P<0.001). Inter observer agreement was poor to moderate for (67)Ga imaging (kappa 0.19-0.59) and good to very good for (18)F-FDG PET (kappa 0.65-1.00). CONCLUSION: (18)F-FDG PET is more sensitive than (67)Ga imaging in the assessment of sarcoidosis activity with regard to the mediastinum, hila, lymph nodes and extra pulmonary lesions in general. Furthermore, (18)F-FDG PET demonstrates a very good inter observer agreement in contrast with (67)Ga imaging and (18)F-FDG PET is therefore the nuclear imaging technique of choice in sarcoidosis assessment.

Weight loss after laparoscopic adjustable gastric banding is not caused by altered gastric emptying.

BACKGROUND: In order to know the role of gastric emptying in the mechanism of weight loss and early satiety after a restrictive surgical procedure for treatment of morbid obesity, a consecutive series of patients were scintigraphically investigated before and after laparoscopic adjustable gastric banding. METHODS: Sixteen patients undergoing laparoscopic adjustable gastric banding underwent preoperatively, and at 6 months postoperatively, a gastric emptying study (solid meal and single isotope). Esophageal retention time, lag phase, peak activity time, gastric emptying rate, fundus emptying rate, and weight loss were recorded. Upper GI symptom assessment was carried out by using a standardized questionnaire. Gastric emptying parameters were correlated with the upper GI symptoms. RESULTS: Gastric band placement showed no significant influence on postoperative gastric emptying rate [median % (interquartile range): 42 (23.3-59) preoperatively vs 38 (31-71) postoperatively and fundus emptying rate: 59(37-91) preoperatively vs 70 (53-89) postoperatively]; however, an increase in early satiety was found. Neither gastric emptying rate nor fundus emptying rate showed a relation with early satiety or weight loss. Furthermore, no correlation was found between early satiety and lag phase, esophageal retention time, start of activity, and peak activity time in proximal stomach. CONCLUSION: Laparoscopic adjustable gastric banding seems not to affect gastric emptying. Neither a relation between postoperative gastric emptying rate and weight loss nor between early satiety and weight loss was found. Therefore, it is unlikely that gastric emptying plays a role in the mechanism of weight loss following laparoscopic adjustable gastric banding.

Severe hypertension in children with renovascular disease.

Renovascular disease is an important cause of hypertension in children and is associated with considerable morbidity and mortality risks. Secondary hypertension is more common in children than in adults, with children accounting for 75% to 80% of cases. In 70% of secondary hypertension in children, the cause is fibromuscular hyperplasia. Other associated conditions are aorto-aortitis, the midaortic syndrome, and Williams-Bueren syndrome. Imaging techniques have an important role in the early discovery of renal artery stenosis. Although renal arteriography remains the definitive method, noninvasive and less invasive radiographic procedures such as ultrasonography with duplex Doppler scanning and radionuclide scintigraphy have been used as adjunct diagnostic tools in children. The authors describe three young children with renovascular hypertension in whom dynamic radionuclide scintigraphy with Tc-99m MAG3 played an essential role in the diagnosis of renovascular hypertension.

Quantitative analysis of 99Tcm-sestamibi myocardial perfusion SPECT using a three-dimensional reference heart: a comparison with experienced observers.

BACKGROUND: Quantification of myocardial perfusion single photon emission computed tomography (SPECT) may improve scintigraphic analysis. Recently, a fully operator independent technique for the quantification of myocardial perfusion SPECT was described, based on a normal three-dimensional averaged reference heart. The purpose of this study was to compare the automated SPECT quantification technique with experienced observers. METHODS: A total of 43 patients, 36 with one-vessel coronary artery disease (CAD) and seven with a low likelihood of CAD, underwent 99Tcm-sestamibi SPECT (99Tcm-MIBI SPECT). Three experienced observers and a panel (composed of the three observers), blinded to the clinical and angiographic data, analysed the size and severity of perfusion defects and the relation to the distribution areas of the coronary arteries. Inter-observer agreement was calculated by using kappa (kappa) statistics. RESULTS: The inter-observer agreement between the human observers and the automated quantitative analysis, for severity and size of perfusion abnormality, was moderate (kappa range 0.38-0.68), while this was fair between three individual observers (kappa range 0.36-0.87) and good between the individual observers and the panel (kappa range 0.63-0.89). There were no differences between the quantitative analysis and the panel in the allocation of perfusion abnormalities to the affected coronary artery. CONCLUSIONS: The operator independent quantification method showed a moderate agreement with individual observers and a panel analysis for size and severity of perfusion abnormalities. The automatic quantification has a similar ability to assign perfusion abnormalities to the diseased coronary artery as compared to an expert panel.

Effect of L-NMMA on postprandial transient lower esophageal sphincter relaxations in healthy volunteers.

In a previous study we showed that nitric oxide (NO) synthesis inhibition by NG-monomethyl-L-arginine (L-NMMA) reduced the number of transient lower esophageal sphincter relaxations (TLESRs) triggered by gastric balloon distention. The role of NO in postprandial TLESRs and gastroesophageal reflux, however, is unknown. Therefore, we studied the effect of L-NMMA on meal-induced TLESRs and reflux episodes with simultaneous recording of esophageal peristalsis, intraesophageal and intragastric pH, and gastric emptying in healthy volunteers. Ingestion of a solid meal resulted in an increase in TLESRs [8.5 (6.3-11.0) 60 min] which was significantly inhibited by L-NMMA [6.0 (4.0-8.8) 60 min, P < 0.05]. In addition, the total number of reflux episodes was reduced. L-NMMA had no effect on intragastric meal distribution and gastric emptying, but attenuated the postprandial increase in intragastric pH. These results confirm the involvement of NO in the neurocircuitry underlying the triggering of TLESRs. The reduction in reflux by L-NMMA has to be confirmed in patients with gastroesophageal reflux disease. NO may be involved in the regulation of gastric acid secretion.

Prognostic value and quality of life in patients with normal rest thallium-201/stress technetium 99m-tetrofosmin dual-isotope myocardial SPECT.

BACKGROUND: The prognostic value of normal dual-isotope single photon emission computed tomography (SPECT), with technetium 99m-tetrofosmin for the stress images, is not well known. Furthermore, thallium-201 cross talk in the Tc-99m window may reduce the defect severity of the Tc-99m images. METHODS AND RESULTS: In a consecutive series of 610 patients, 246 patients with normal rest and stress SPECT images by means of visual semiquantitative analysis were included. The patients' pre-test likelihood of coronary artery disease was determined, based on age, sex, symptoms, and the results of stress electrocardiography. Quality of life was assessed by using a mailed self-administered general quality-of-life questionnaire. We compared the mean scores (8 dimensions) of our study population with the scores of 1063 control subjects, sampled randomly out of the inhabitant register of a Dutch city. The mean follow-up period was 25+/-3 months. Compared with the control group, patients in our study scored lower (less perceived health) for all dimensions of the SF-36 (P<.05), suggesting a selection of symptomatic or otherwise diseased patients. The primary cardiac event rate was 0.4% per year. The cardiac events occurred in patients with an intermediate-to-high pre-test likelihood of disease and negative or nondiagnostic exercise electrocardiographic results. In a subset of patients with a high pre-test likelihood of coronary artery disease (more than 85%), the primary cardiac event rate was 0.7% per year. CONCLUSIONS: Patients with normal results on dual-isotope myocardial perfusion scintigraphy, performed with Tc-99m-tetrofosmin for the stress images, have an excellent prognosis. Furthermore, our results suggest that Tl-201 cross talk in the Tc-99m window may be low and functionally and clinically unimportant.

[Value of the 'non-diagnostic' lung scan--further classification as to the risk of pulmonary embolism not reliable]. / De waarde van de 'niet-diagnostische' longscan--verdere classificatie naar de kans op longembolie niet betrouwbaar.

OBJECTIVE: To determine to what extent the 'non-diagnostic' lung scans made because of a clinical suspicion of pulmonary embolism enable further determination of the risk of pulmonary embolism. DESIGN: Retrospective. METHOD: All non-diagnostic lung perfusion ventilation scans made in the Academic Medical Centre of Amsterdam in 1997 of 114 patients in succession (55 males and 59 females aged 27-85 years) were subjected to blind and independent re-evaluation by three observers (an experienced nuclear medicine expert, an experienced and an inexperienced intern) who, using a lung segment chart, estimated the risk of embolism as < 25%, 25-50%, 50-75% and > 75%. They did this first without and then with the chest X-ray. The findings were grouped on the basis of accordance or non-accordance with the pulmonary angiogram. The interobserver agreement was calculated by means of kappa statistics. RESULTS: Of 58 patients the lung scan could be compared with a chest X-ray and a pulmonary angiogram. In 43 patients with a normal angiogram the observers in an average of 50% of the scans estimated the risk of pulmonary embolism as < 25%, as against 25-50% in 27%, 50-75% in 9% and > 75% in 5%. In 15 patients with a deviant pulmonary angiogram, these figures were 22%, 38%, 20%, and 12%, respectively. The interobserver kappa for evaluation without chest X-ray was < or = 0.16, as against < or = 0.41% with the chest X-ray. CONCLUSIONS: A reliable classification of the risk of pulmonary embolism was not possible on the basis of non-diagnostic lung scans, regardless of whether the patient did or did not have pulmonary embolism. The interobserver variability was less when the lung scan was evaluated together with the chest X-ray, but even so it was unacceptably high.

Indium-111-antimyosin scintigraphy in the early detection of heart damage after anthracycline therapy in children.

PURPOSE: To determine the value of indium-111-antimyosin ((111)In-AM) scintigraphy in the early detection of myocardial damage in children treated with doxorubicin. PATIENTS AND METHODS: Twelve planar scintigrams were made of eight patients (seven children and one young adult; mean age, 12 years). Three scans were obtained before doxorubicin therapy in three patients, and nine scans were obtained during doxorubicin therapy in seven patients. The heart-to-lung ratio (HLR) was calculated. Left ventricular function was assessed by echocardiography before and during therapy by measuring the fractional shortening (FS). RESULTS: The HLR of the three baseline scans was below 1.5, within the normal range for adults. Six of the seven patients whose scans were obtained during chemotherapy had abnormal HLR values (> 1.5). One patient had severe myocyte damage and showed an early increase in the HLR (2.3) after a cumulative doxorubicin dose of 150 mg/m(2). The FS measured by echocardiography was normal throughout therapy, and the final cumulative dose of doxorubicin was 450 mg/m(2). This patient developed fatal clinical heart failure 3 months after completion of chemotherapy. In one patient, who was pretreated with the cardioprotective agent dexrazoxane, the HLR remained within normal limits during therapy. CONCLUSION: (111)In-AM scintigraphy seems to be suitable to detect early myocardial damage after a cumulative doxorubicin dose of 150 mg/m(2 )in children and may be useful for identifying children who are at increased risk of developing cardiac sequelae.

Determinants of longterm outcome of radioiodine therapy of sporadic non-toxic goitre.

OBJECTIVE: Radioiodine treatment is effective in reducing the size of sporadic nontoxic goitre, albeit at the expense of a high incidence of postradiation hypothyroidism. The decrease in goitre size, however, is not observed in all subjects, and little is known about recurrent goitre growth after 131I therapy. The aim of the present study was to evaluate which factors determine the longterm outcome of 131I treatment in patients with sporadic nontoxic nodular goitre, in terms of changes in both thyroid size and thyroid function. STUDY DESIGN: Retrospective follow-up study. PATIENTS: Fifty patients with sporadic nontoxic nodular goitre were evaluated who had been treated in our institution with 131I (mean dose 4.4 MBq/g thyroid) in the period 1988-95. Nine patients received a second dose of 131I and one a third. Median follow-up time was 41 months (range 24-115). MEASUREMENTS: Thyroid function was assesed by TSH and FT4 index, and thyroid volume by ultrasound in 46 patients, by scintiscan using the Himanka formula in three and by CT-scan in one. The response to treatment was defined as a decrease in thyroid volume of greater than 13% (i.e. the mean + 2SD of the coefficient of variation of volume measurements), and recurrent goitre as an increase in thyroid volume greater than 13% after an initial response. RESULTS: Goitre size decreased from a median value of 82 ml (range 17-325) to 37 ml (range 6-204) two years after 131I treatment, a median reduction of 49%. The decrease in goitre size was directly related to the dose of 131I (r = 0.50, P = 0.0003) and indirectly to baseline goitre size (r = - 0.35, P = 0.006). Seven patients (14%) were nonresponders, and four (8%) experienced recurrent goitre growth after 3-5 years. These 11 patients (22%) when compared to the remaining 39 responders (78%) had larger goitres with more often a dominant nodule, and had received a lower 131I dose. The efficacy of a second dose of 131I (median reduction in goitre size 37%) was comparable to the first dose. Hypothyroidism occurred in 24 patients (48%), mostly in the first two years after treatment; 11 had overt and 13 subclinical hypothyroidism. Kaplan Meier statistics indicated a probability of 58% for developing hypothyroidism after 8 years. Hypothyroid patients had a smaller initial goitre size and a higher prevalence of TPO antibodies and a family history of thyroid disease than the patients who remained euthyroid; the 131I dose did not differ between the two groups. CONCLUSIONS: The size of sporadic nontoxic goitres is reduced on average by 50% after a single dose of 4.77 MBq 131I/g thyroid. Independent determinants of the relative decrease in thyroid volume are administered 131I dose and initial goitre size. Nonresponders (14%) and those with late recurrence of goitre growth (8%) have larger goitres and more often dominant nodules than responders. Determinants of postradioiodine hypothyroidism (cumulative risk 58% after 8 years) are the presence of TPO antibodies, a family history of thyroid disease and a relatively small goitre. The implications of these findings are that the efficacy of a given 131I dose can be enhanced when administered at an earlier stage when the goitre is still smaller, albeit at the expense of an increased risk for developing hypothyroidism.

Disturbed enterogastric inhibitory reflex after esophageal resection and narrow gastric tube reconstruction.

BACKGROUND/AIMS: The gastric emptying pattern after esophageal resection and narrow gastric tube reconstruction is determined by multiple factors. One of the possible factors is a disruption in the neurohumoral enterogastric inhibitory reflex. The aim of the present study was to determine the possible alterations of this reflex after esophageal resection and narrow gastric tube reconstruction. METHODS: Nine patients each underwent two gastric tube emptying studies, one without and one with high caloric duodenal tube feeding. The dual isotope scintigraphic data were corrected for subject movement, radionuclide decay, downscatter and gamma-ray attenuation. RESULTS: The median gastric tube emptying rate of solid food was 57%/h (range 27-195). The median T(1/2) of liquid food was 67 (range 4->80) min. Both for solid and for liquid food, the gastric tube emptying patterns without and with duodenal tube feeding were not significantly different. CONCLUSION: The neurohumoral enterogastric inhibitory reflex is disrupted after esophageal resection and narrow gastric tube reconstruction, which may contribute to disturbed gastric emptying.

Ultrasonographic versus scintigraphic measurement of thyroid volume in patients referred for 131I therapy.

The activity of 131I to be administered as therapy to patients with thyroid disease is usually calculated from 24 h radioiodine uptake and thyroid volume. The aim of the present study was to compare thyroid volume, measured by scintigraphy and ultrasonography, to evaluate the impact of these methods on the calculated 131I dose. Forty patients (20 with diffuse toxic goiter and 20 with multinodular toxic or nontoxic goiter) were investigated. On the same day, thyroid volume was measured by ultrasonography (using transverse scans at 5 mm intervals) and by scintigraphy, using either the ellipsoid formula (SC-E: [symbol: see text]/6 x height x width x depth) or the Himanka formula (SC-H: 0.33 x (planimetric surface in pixels)3/2). With ultrasonography, the size of diffuse goiters was smaller than that of nodular goiters (median values and range: 18 ml (11-46) and 50 ml (14-198) respectively, P < 0.001). Both scintigraphic methods, however, failed to demonstrate a significant difference between diffuse and nodular goiter size. In patients with diffuse goiter, thyroid volume measured by SC-E did not differ from that measured by ultrasonography, whereas thyroid size was overestimated by 53% using the Himanka formula. In contrast, in patients with nodular goiter, thyroid volume measured by SC-H did not differ from that measured by ultrasonography, whereas the ellipsoid formula underestimated thyroid size by 48%. The overestimation of diffuse goiter size by the Himanka formula resulted in a relatively modest median excess of 96 MBq (range -118 to +248 MBq) of the calculated 131I dose. The underestimation of nodular goiter size by the ellipsoid formula resulted in a calculated dose that was 278 MBq lower (range -1624 to +141 MBq). The median calculated 131I dose based on the Himanka formula was not different from that based on ultrasound, but large differences in calculated 131I dose (up to 1280 MBq) were found in individual cases. In conclusion, thyroid volume can be assessed with accuracy by scintigraphy using the ellipsoid formula in patients with diffuse goiter. Wide differences, however, are observed in the size of nodular goiters measured by scintigraphy and ultrasonography.

Is intrasound vibration useful in the diagnosis of occult scaphoid fractures?

This study was designed to confirm the results of Finkenberg et al. (J Hand Surg 1993;18A: 4-7), who found a high sensitivity (100%) and specificity (95%) of the intrasound vibration method in diagnosing occult scaphoid fractures. These occult scaphoid fractures are not visible on x-ray films, but clinically the patients are suspected of having a scaphoid fracture. A vibratory apparatus is placed over the anatomical snuff-box and a vibration of 100 mW is emitted; a painful sensation is produced if the scaphoid is fractured. Thirty-seven consecutive patients with a clinically suspected scaphoid fracture were evaluated. In 6 patients, a scaphoid fracture was radiographically identified; in the remaining 31 patients, a 3-phase bone scan was obtained. Eleven wrists showed increased uptake over the scaphoid and were considered to have an occult scaphoid fracture. In this group, bone scintigraphy was used as the reference standard. The vibration test was painful in 1 of 6 patients with a proven scaphoid fracture and in 3 of the 11 patients with a positive bone scan. In contrast to the results of Finkenberg et al, the intrasound vibration method shows a sensitivity of 24%, a specificity of 85%, a positive predictive value of 40%, and a negative predictive value of 65%. We conclude that the accuracy of intrasound vibration is low and that it is not useful in the diagnosis of scaphoid fractures.

The role of renal scintigraphy in the diagnosis and follow-up of unilateral ATN after complete bilateral distal ureteral obstruction as a complication of acute appendicitis.

Acute anuria due to bilateral distal ureteral obstruction developed in two boys, ages 7 and 13, several days after appendectomy, without sonographic signs of hydronephrosis or hydroureters. Decompression was achieved after introduction of ureteric stents. This failed on the left side in one patient, and unilateral acute tubular necrosis (ATN) subsequently developed on that side. Although bilateral decompression was successful in the second patient, ATN had already developed on the left side. In both patients, Tc-99m MAG3 renal scintigraphy proved to be an important tool in diagnosing unilateral ATN and for evaluating the recovery from this rare complication.

Improved wrist fracture localization with digital overlay of bone scintigrams and radiographs.

UNLABELLED: The diagnosis of scaphoid fracture is often difficult and of interest in traumatology. Because of the low sensitivity of repeated scaphoid radiographs, a bone scintigram is advocated and considered the gold standard. In this study, we tried to simplify the interpretation of the bone scintigram of hand and wrist in localizing the hot spot by the digital overlay of the radiograph and the bone scintigram, using a simple device, in patients after wrist trauma. METHODS: Twenty-one consecutive patients (22 wrists) with clinically-suspected scaphoid fracture and negative initial radiographs were included. The PA view of the wrist was obtained with the hand of the patient placed in an acrylic device with three lead markers. For the bone scan, a similar device was used with 57Co markers at the same positions. We called this device the "hand-fix." The PA radiograph was digitized with a videocamera and overlaid on the bone scan. Each bone scan was interpreted twice by each of three observers, one nuclear physician and two residents in nuclear medicine. The first interpretation was made without the digital overlay, and the second was made with the digital overlay. RESULTS: The bone scintigrams were positive in the scaphoid, distal radius and in other carpal bones. Out of the 22 bone scans, Observer 1 judged 19 correctly, Observer 2 judged 16 correctly and Observer 3 judged 10 correctly without the digital overlay images. All three observers gave a correct localization in the 22 wrists using the digital overlay images. CONCLUSION: The digital overlay of a radiograph and a bone scintigram, using the hand-fix, simplifies and improves interpreting and localizing the hot spot on bone scintigrams in patients with wrist injuries.

Should imaging at stress always be followed by imaging at rest in Tc-99m MIBI SPECT? A proposal for a selective referral and imaging strategy.

OBJECTIVES: We addressed the question whether in patients with cardiac chest pain referred for stress myocardial perfusion scintigraphy, Tc-99m MIBI SPECT stress imaging should always be followed by a rest imaging procedure. BACKGROUND: Using Tc-99m MIBI imaging a stress rest sequence is usually performed implying that the resting study always follows the stress study irrespective of the results of the stress study. As a normal stress study would eliminate a subsequent resting study, it appears desirable to potentially define certain subsets of patients in whom a normal stress study can be expected in order to determine a more selective referral approach to the nuclear medicine department. The consequences of such a more streamlined approach would less impose on the logistics of the department of nuclear medicine, with decrease of investigation time, radiation dose, and costs in a time of retrenchment in the medical sector. METHODS: A consecutive series of 460 patients (mean age 58.2 years) was studied who were stratified to 269 patients without prior myocardial infarction, and to 191 patients with documented evidence of a previously sustained myocardial infarction. All patients underwent Tc-99m MIBI SPECT imaging according to a two-day stress-rest protocol. RESULTS: Patients with and without a previous myocardial infarction showed suboptimal overall predictive accuracies for the exercise electrocardiograms (58% and 60%, respectively). In the total group of 460 patients, 94 (20%) patients showed a normal stress-rest Tc-99m MIBI SPECT; this occurred in 86/269 (32%) patients without a previous myocardial infarction and in only 8/191 (4%) patients with a previous myocardial infarction. CONCLUSIONS: Patients with a stress defect at Tc-99m MIBI SPECT imaging should always undergo a resting SPECT study irrespective of the clinical and stress electrocardiographic findings. As patients without a previous myocardial infarction had a normal stress SPECT study in almost one-third (32%) of patients compared to only 4% in patients with a previously myocardial infarction, it may be useful to employ different referral and imaging strategies i.e., a stress-only versus a stress-rest procedure. To schedule referring patients differently according to the presence or absence of a previously sustained myocardial infarction may be cost-saving, less demanding for the nuclear medicine personnel, and patient-convenient. In addition, a stress-only imaging procedure reduces radiation exposure to the individual patient.

Implementation of technetium-99m MIBI SPECT imaging guidelines: optimizing the two day stress-rest protocol.

OBJECTIVES: In a previous study in 460 patients, we found that in patients with suspected or known coronary artery disease undergoing stress-rest technetium-99m sestamibi (MIBI) SPECT myocardial perfusion imaging, rest SPECT imaging could be withhold in approximately 20% of patients because of a completely normal stress study. The present study was set up to evaluate the consequences of the implementation of this finding in a subsequent population of patients, and to set standards for the variety of protocols now used for MIBI SPECT imaging. METHODS: Within a period of 4 months, 235 consecutive patients referred for MIBI SPECT scintigraphy were studied. All patients had stable cardiac chest pain and underwent symptom-limited exercise MIBI SPECT perfusion imaging. The stress SPECT images were reconstructed and evaluated immediately after acquisition of the images. In case of a clearly normal stress SPECT study, rest imaging was cancelled. RESULTS: Twenty-six of 235 patients (11%) had a completely normal stress MIBI SPECT study and the rest SPECT imaging procedure could be subsequently cancelled. In 20 patients (9%) the stress SPECT was inconclusive, and in 189 (80%) of patients stress imaging was clearly abnormal. In the first month of the study, the nuclear medicine physicians and cardiologists would interprete only 6% of the stress images as normal, while this number increased to 13% after 9 weeks, with a mean of 11% for the whole investigation period of 4 months. CONCLUSION: In patients undergoing stress MIBI SPECT imaging, it was found justified to cancel rest MIBI SPECT imaging in at least 11% of patients because of a completely normal stress SPECT. As 9% of the images were inconclusive, the number of normal stress images could theoretically increase to 20% if reliable measures are taken to improve reading accuracy. This number is in close agreement with the number of normal stress studies previously reported by our institution and would lead to a considerable reduction of radiation dose, costs, and increased convenience for an important subset of patients.