Long-term effects of myotomy and partial fundoplication for esophageal achalasia

Controversy persists in the surgical approach to treat esophageal achalasia. This investigation reports the long-term effects of esophageal myotomy and partial fundoplication in treating this disorder. From 1984 to 1998, 32 patients with achalasia underwent myotomy and partial fundoplication (Belsey Mark IV) using a left thoracotomy. The median follow up is 7.2 years. Assessments include clinical evaluation, esophagogram, radionuclide transit, manometry, 24-h pH, and endoscopy. There is no complication and no mortality. Preoperative assessment was compared with that in 0-3, 3-7, and 7-16 postoperative years. Clinically, the prevalence of dysphagia was decreased from 100% to 6%, 12%, and 13%, respectively (P < 0.001). Heartburn remains unchanged (P > 0.25). On radiology, the prevalence of barium stasis was decreased from 97% to 44%, 48%, and 47%, respectively (P=0.001), whereas a pseudo-diverticulum was observed in two-thirds of patients after operation (P=0.001). Percent radionuclide stasis at 2 min was measured as 70%, 17%, 20%, and 20%, respectively (P=0.001). Manometrically, lower esophageal sphincter (LES) gradient was decreased from 29 to 10, 9, and 9 mmHg, respectively (P=0.001). LES relaxation was improved from 41% preoperatively to 100% postoperatively at each postoperative period (P < 0.001). An abnormal acid exposure was observed in four patients after the operation. Endoscopy documented mucosal damage in three patients (P > 0.25). In conclusion, on long-term follow up, myotomy and partial fundoplication for achalasia relieve obstructive symptoms and improve esophageal emptying, and reduce LES gradient and improve LES relaxation. Acid reflux is recorded in 13% of patients and esophageal mucosal damage is identified in 11% of the patient population. A longer myotomy not covered by the fundoplication results in pseudodiverticulum formation and increased esophageal retention.

Radiolabeled peptides in the detection of deep venous thrombosis

Venous thrombosis and pulmonary embolism are major clinical problems that result in significant morbidity and mortality. It is estimated that 600,000 cases of pulmonary embolism occur each year in the United States, resulting in the death of approximately 100,000 patients. Most of these pulmonary emboli arise from deep venous thrombosis (DVT). The clinical diagnosis of DVT is unreliable. Only a third of patients with a clinical suspicion of DVT have objective evidence of the disease, and half of patients with proven DVT do not have any clinical symptoms. Although ascending contrast venography is the present standard for the diagnosis of DVT, duplex ultrasonography, which is increasingly used in combination with color Doppler flow imaging, is accepted as a useful clinical afternative to contrast venography. Both contrast venography and ultrasonography are imaging procedures that detect changes in venous anatomy that are caused by the presence of an intraluminal thrombus that is sufficiently formed either to reduce vascular filling with contrast medium or to resist compression. However, these imaging procedures do not reflect the metabolic activity of the clot, and therefore, they may overestimate the presence of active clots. The sensitivity of ultrasonography is also limited by various disease-related and technical factors. An alternative approach to the diagnosis of acute DVT is to detect a molecular marker of acute DVT that is not present in old, organized DVT. Recent advances in biotechnology permit the use of highly specific synthetic peptide or small molecular markers, which are involved in the acute stages of DVT formation and can be labeled efficiently with 99mTc. 99mTc-apcitide, a glycoprotein (GP IIb/IIIa) receptor antagonist previously known as 99mTc-P280, has been approved recently by the Food and Drug Administration for the clinical detection of acute DVT. Two other agents are currently under clinical investigation: 99mTc-DMP 444, which is another GP IIb/IIIa receptor antagonist, and 99mTc-Fibrin-Binding Domain (FBD), a radio-labeled fibrin-binding domain of fibronectin. Different clinical studies have shown a high diagnostic accuracy with these synthetic 99mTc-labeled peptides in the detection of acute DVT. Although further studies are needed to fully appreciate all of the diagnostic potential of these radiopharmaceuticals, the clinical introduction of 99mTcapcitide scintigraphy will certainly be helpful in expanding the use of nuclear medicine in a specific field in which it used to play a relatively marginal role.

Enhanced detection of reversible perfusion defects by Tc-99m sestamibi compared to Tc-99m tetrofosmin during vasodilator stress SPECT imaging in mild-to-moderate coronary artery disease

OBJECTIVES

We prospectively compared dipyridamole single-photon emission computed tomography (SPECT) imaging with Tc-99m sestamibi and Tc-99m tetrofosmin for the detection of reversible perfusion defects in patients with mild-to-moderate coronary artery disease.

BACKGROUND

Tc-99m tetrofosmin has a lower first-pass myocardial extraction fraction compared to Tc-99m sestamibi and thus could underestimate mild perfusion defects.

METHODS

Eighty-one patients with 50% to 90% stenosis in one or two major epicardial vessels without previous myocardial infarction, and seven with <5% probability of coronary artery disease underwent dipyridamole SPECT imaging with both agents. The SPECT data were analyzed quantitatively.

RESULTS

Tc-99m sestamibi detected reversible perfusion defects in a greater number of segments (total 363 and 285, p < 0.001, and mean +/- SD, 2.2 +/- 3.0 and 1.8 +/- 2.5 per patient, p = 0.008, for Tc-99m sestamibi and Tc-99m tetrofosmin, respectively), demonstrated a larger extent of perfusion defect (mean +/- SD, 15.8% +/- 12.3% and 12.0% +/- 11.4%, p < 0.03, for Tc-99m sestamibi and Tc-99m tetrofosmin, respectively) and more often correctly identified patients with disease in more than one coronary artery (p = 0.02). There was better defect contrast with Tc-99m sestamibi (defect/normal wall count ratios were 0.60 +/- 0.15 vs. 0.73 +/- 0.14 for Tc-99m sestamibi and Tc99m tetrofosmin, respectively, p = 0.01, for reversible defects seen in identical segments with both agents; and 0.73 +/- 0.16 vs 0.79 +/- 0.17, respectively, p <0.01, for reversible defects detected with either agent alone). There was no significant difference in diagnostic sensitivity or image quality.

CONCLUSIONS

These differences between two commonly used tracers may have significant diagnostic and prognostic implications.

Combined corrections for attenuation, depth-dependent blur, and motion in cardiac SPECT: a multicenter trial

BACKGROUND

The diagnostic accuracy of cardiac single photon emission computed tomography (SPECT) is limited by image-degrading factors, such as heart or subject motion, depth-dependent blurring caused by the collimator, and photon scatter and attenuation. We developed correction approaches for motion, depth-dependent blur, and attenuation and performed a multicenter validation.

METHODS AND RESULTS

Motion was corrected both transversely and axially with a cross-correlation technique. Depth-dependent blurring was corrected by first back-projecting each projection and then applying a depth-dependent Wiener filter row by row. Attenuation was corrected with an iterative, nonuniform Chang algorithm, based on a transmission scan-generated attenuation map. We validated these approaches in 112 subjects, including 36 women (20 healthy volunteers, 8 angiographically normal patients, and 8 patients with coronary artery disease [CAD] found by means of angiography) and 76 men (23 healthy volunteers, 10 angiographically normal patients, and 43 patients with CAD found by means of angiography). Either technetium 99m or thallium 201 was used for emission; either gadolinium 153 or Tc-99m was used for transmission. Images were reconstructed and blindly interpreted with a 5-point scale for receiver operating characteristic analysis in 2 ways: motion correction plus a Butterworth filter, and combined motion and blur and attenuation corrections. The interpretation by means of consensus was for the overall presence of CAD and vascular territory. The receiver operating characteristic curves for overall presence and each of the 3 main coronary arteries were all shifted upward and to the left and had larger areas under the curve, for combined corrections compared with motion correction and Butterworth. Sensitivity/specificity for motion correction and Butterworth were 84/69, 64/71, 32/94, and 71/81 overall for the left anterior descending, the right coronary artery, and circumflex territories, respectively, compared with 88/92, 77/93, 50/97, and 74/95, respectively, for the combined corrections.

CONCLUSIONS

The proposed combined corrections for motion, depth-dependent blur, and attenuation significantly improve diagnostic accuracy, when compared with motion correction alone.

123I-IPPA SPECT for the prediction of enhanced left ventricular function after coronary bypass graft surgery. Multicenter IPPA Viability Trial Investigators. 123I-iodophenylpentadecanoic acid

Fatty acids are the prime metabolic substrate for myocardial energy production. Hence, fatty acid imaging may be useful in the assessment of myocardial hibernation. The goal of this prospective, multicenter trial was to assess the use of a fatty acid, 123I-iodophenylpentadecanoic acid (IPPA), to identify viable, hibernating myocardium.

METHODS

Patients (n = 119) with abnormal left ventricular wall motion and a left ventricular ejection fraction (LVEF) < 40% who were already scheduled to undergo coronary artery bypass grafting (CABG) underwent IPPA tomography (rest and 30-min redistribution) and blood-pool radionuclide angiography within 3 d of the scheduled operation. Radionuclide angiography was repeated 6-8 wk after CABG. The study endpoint was a > or =10% increase in LVEF after CABG. The number of IPPA-viable abnormally contracting segments necessary to predict a positive LVEF outcome was determined by receiver operating characteristic (ROC) curves and was included in a logistic regression analysis, together with selected clinical variables.

RESULTS

Before CABG, abnormal IPPA tomography findings were seen in 113 of 119 patients (95%), of whom 71 (60%) had redistribution in the 30-min images. The LVEF increased modestly after CABG (from 32% +/- 12% to 36% +/- 8%, P< 0.001).A > or =10% increase in LVEF after CABG occurred in 27 of 119 patients (23%). By ROC curves, the best predictor of a > or =10% increase in LVEF was the presence of > or =7 IPPA-viable segments (accuracy, 72%; confidence interval, 64%-80%). Among clinical and scintigraphic variables, the single most important predictor also was the number of IPPA-viable segments (P = 0.008). The number of IPPA-viable segments added significant incremental value to the best clinical predictor model.

CONCLUSION

Asubstantial increase in LVEF occurs after CABG in only a minority of patients (23%) with depressed preoperative function. The number of IPPA-viable segments is useful in predicting a clinically meaningful increase in LVEF.

Acute thromboscintigraphy with (99m)Tc-apcitide: results of the phase 3 multicenter clinical trial comparing 99mTc-apcitide scintigraphy with contrast venography for imaging acute DVT. Multicenter Trial Investigators

(99m)Tc-apcitide (formerly known as (99m)Tc-P280) is a radiolabeled peptide that binds with high affinity and specificity to the glycoprotein IIb/IIIa receptors expressed on the activated platelets that are involved in acute thrombosis. The purpose of the phase 3 multicenter clinical trials was to compare (99m)Tc-apcitide scintigraphy with contrast venography for imaging acute deep venous thrombosis (DVT).

METHODS

A total of 280 patients were enrolled in 2 clinical trials conducted in North America and Europe. Patients were to be within 10 d of onset of signs and symptoms of acute DVT or within 10 d of surgery associated with a high risk of DVT. (99m)Tc-apcitide scintigraphy and contrast venography were to be performed within 36 h. Planar scintigraphic images were obtained at 10, 60, and 120-180 min after injection. (99m)Tc-apcitide scintigrams and contrast venograms were read with masking and also by the institutional investigators.

RESULTS

Of a total of 243 patients who were evaluable, 61.7% were receiving heparin at the time of imaging. Masked reading of (99m)Tc-apcitide scintigraphy, compared with masked reading of contrast venography, had a sensitivity, specificity, and agreement of 73.4%, 67.5%, and 69.1%, respectively, which met the prospectively defined target efficacy endpoint in both trials. Institutional reading of (99m)Tc-apcitide scintigraphy, compared with institutional reading of contrast venography, had a sensitivity, specificity, and agreement of 75.5%, 72.8%, and 74.0%, respectively. However, the entire trial population included patients with a history of DVT who may have had old, nonacute venous thrombi that could confound the venography results. Therefore, data from patients having no history of DVT or pulmonary embolism and who presented within 3 d of onset of signs and symptoms (n = 63), i.e., patients for whom a venogram would be expected to be positive only if acute DVT were present, also were analyzed as a subset. In these patients, institutional reading of (99m)Tc-apcitide scintigraphy, compared with institutional reading of contrast venography, had a sensitivity, specificity, and agreement of 90.6%, 83.9%, and 87.3%, respectively.

CONCLUSION

(99m)Tc-apcitide scintigraphy is a new diagnostic modality that is highly sensitive for imaging acute DVT.

Comparison of early and delayed scintigraphy with 99mTc-apcitide and correlation with contrast-enhanced venography in detection of acute deep vein thrombosis

Preliminary studies with 99mTc-apcitide (99mTc-P280), a synthetic peptide that binds to glycoprotein IIb/IIIa receptors expressed on activated platelets, have shown promising results in the detection of acute deep vein thrombosis (ADVT). The purpose of this study was to compare the diagnostic value of early and delayed imaging with 99mTc-apcitide in patients with suspected ADVT, using contrast-enhanced venography as the gold standard.

METHODS

Thirty-nine patients (17 women, 22 men; mean age 59 y) with signs or symptoms suggestive of ADVT (within 10 d of onset) and scheduled for contrast-enhanced venography were prospectively studied. The patients were injected with approximately 740 MBq (20 mCi) 99mTc-apcitide within 36 h of contrast-enhanced venography. Both anterior and posterior planar images (8-10 min/view) of the lower extremities using a dual-head gamma camera were obtained at 10, 60 and 120 min after the injection of 99mTc-apcitide. The three sets of images initially were interpreted randomly and separately by three experienced observers unaware of the clinical history, the site of ADVT and results of contrast-enhanced venography. All images from the three sets for a given patient were then analyzed together during a second session. Conventional contrast-enhanced venography was performed on 31 patients before 99mTc-apcitide scintigraphy and in the remaining 8 patients after 99mTc-apcitide scintigraphy. 99mTc-apcitide findings were considered positive forADVT when a focus of increased uptake was found to correspond to the location of a deep vein. Disagreements were resolved by consensus.

RESULTS

Twenty-two patients had ADVT observed on contrast-enhanced venography, whereas 17 had normal findings. Six cases of ADVT were infrapopliteal. One patient did not complete the third set of images with 99mTc-apcitide. The sensitivity of 99mTc-apcitide in detecting ADVT was 63.6% (14/22), 68.2% (15/22), 76.2% (16/21) and 86.4% (19/22) for images obtained at 10, 60 and 120 min and for the three sets analyzed together, respectively. The specificity was 82.4% (14/17), 76.5% (13/17), 88.2% (15/17) and 88.2% (15/17) for images obtained at 10, 60 and 120 min and for the three sets of images together, respectively.

CONCLUSION

Although the set of 99mTc-apcitide images obtained 120 min after injection showed good overall diagnostic accuracy, the combination of at least two sets of images provided the highest accuracy in detecting ADVT.

Results of the Collis-Nissen gastroplasty in patients with Barrett's esophagus

BACKGROUND

Barrett's esophagus (BE) is an advanced stage of gastroesophageal reflux disease. Medical treatment and standard antireflux operations show a high failure rate. An elongated gastroplasty, wrapped by a total fundoplication should provide a tension-free repair with adequate protection against reflux. The aim of this study is to review the operative effects of a Collis-Nissen gastroplasty to treat reflux in Barrett's esophagus.

METHODS

From January 1989 to December 1997, 45 patients with BE (38 men, 7 women) aged 53.5 years, underwent a Collis-Nissen gastroplasty. Mean follow-up is 35.9 months (range, 6 to 110 months). Pre- and postoperative evaluations included symptom assessment, esophagogram, endoscopy, manometry, 24-hour pH study, and esophageal emptying scintigrams.

RESULTS

There were no operative deaths. All reflux symptoms were controlled. Acid reflux was significantly reduced (percent time exposure decreased from 10% to 1%) and lower esophageal sphincter (LES) pressure were restored to normal (LES gradient increased from 4 mm Hg to 11 mm Hg). LES incomplete relaxation was noted in 50% of patients postoperatively. Endoscopically, mucosal damage from reflux healed but the columnar mucosa with intestinal metaplasia persisted.

CONCLUSIONS

The Collis-Nissen gastroplasty, in patients with BE, controls reflux disease, its symptoms, and the mucosal damage associated with this condition. It restores the LES gradient but increases the resistance to bolus transit. There is no regression of the abnormal mucosa despite reflux control.

Comparison between the end-diastolic images and the summed images of gated 99mTc-sestamibi SPECT perfusion study in detection of coronary artery disease in women

BACKGROUND

End-diastolic images (EDI) can be easily derived from technetium 99m-sestamibi gated single photon emission computed tomography (SPECT) perfusion study (SGS). This may reduce the effect of myocardial wall thickening during systole and potentially improve the sensitivity of radionuclide perfusion imaging, especially in patients with small hearts.

METHODS

This prospective study was conducted in 53 consecutive female patients to compare the diagnostic accuracy of EDI with that of the summed images (SI) of SGS. Fifty-three patients with suspected coronary artery disease (CAD), scheduled for coronary angiography within 2 months, were evaluated with SGS. Treadmill stress testing was used in 28 patients, and dipyridamole injection was used in the remaining 25 patients. A 2-day protocol was used as follows: stress test with 25 to 30 mCi of 99mTc-sestamibi and a rest study performed at least 24 hours later with the same dose. Sixteen frames per cardiac cycle were acquired for both the rest and the stress studies. Three end-diastolic frames were used for EDI, and all the 16 frames were summed for SI. SI and EDI data reconstruction were interpreted by 3 experienced blinded observers (consensus reading) during two distinct reading sessions, one with SI alone and the second with EDI alone. The heart was divided into 17 segments.

RESULTS

Coronary angiography showed > or = 50% stenoses in 1 or more major coronary arteries in 38 patients and was normal in 15 patients. The sensitivity was 73.7% (28/38) and 84.2% (32/38), respectively, for SI and EDI. Three of 4 patients with CAD not detected by SI but seen with EDI were considered to have relatively small hearts. The specificity was 86.7% (13/15) and 80.0% (12/15) for SI and EDI, respectively. On a total of 901 segments, 106 ischemic defects were detected by SI and 173 by EDI (P = .001). The segmental agreement between the two techniques was 88.6% (798/901 segments).

CONCLUSION

EDI showed more ischemic defects than SI, and there was also a nonsignificant trend toward an improved sensitivity of EDI in comparison to SI in detection of coronary artery disease in women, especially in patients with small hearts. EDI may be a useful adjunct to the standard perfusion imaging with SGS in such a clinical situation.

The role of 99mTc-sestamibi and other conventional radiopharmaceuticals in breast cancer diagnosis

The wide availability and the extensive use of screening mammography have resulted in an earlier diagnosis of breast cancer and in a significant reduction in the relative risk of dying from this disease. Despite technical improvements and major advantages associated with the use of mammography (and breast ultrasound), this procedure has some limitations in clinical practice, especially in women with dense breast tissue, implants, severe dysplastic disease, or significant architectural distortion following breast surgery or radiation therapy. Different noninvasive imaging techniques have been evaluated to overcome these limitations. Nuclear medicine also has been actively involved in the detection of breast cancer, using various types of radiopharmaceuticals. Currently, there are three radiotracers commonly used for breast imaging or scintimammography in either clinical practice or research: 99mTc-sestamibi and 99mTc-tetrofosmin (two agents used for myocardial perfusion imaging) and 99mTc-MDP (methylene diphosphonate, used for bone scintigraphy). 99mTc-sestamibi was the first radiopharmaceutical to be approved by the FDA for scintimammography. Several prospective studies have shown that the overall sensitivity of 99mTc-sestamibi scintimammography in detection of breast cancer was 85%, the specificity was 89%, and the positive and negative predictive values were 89% and 84% respectively. Similar numbers have been demonstrated for 99mTc-tetrofosmin and 99mTc-MDP scintimammography. Although not indicated as a screening procedure for the detection of breast cancer, scintimammography may play a useful and significant role in various specific clinical indications such as nondiagnostic or difficult mammography, and evaluation of high-risk patients, tumor response to chemotherapy, and axillary lymph node metastatic involvement.

Fasting and nonfasting iodine-123-idophenylpentadecanoic acid myocardial SPECT imaging in coronary artery disease

Iodine-123-labeled idophenylpentadecanoic acid (IPPA) metabolic imaging has been shown to be clinically useful for the identification of myocardial viability in patients with coronary artery disease and left ventricular dysfunction. Imaging is usually performed under fasting conditions since nonfasting conditions may affect myocardial uptake of 123I-IPPA. The purpose of this study was to examine the impact of dietary condition on 123I-IPPA metabolic imaging.

METHODS

Forty patients with stable coronary artery disease underwent, in randomized order and on separate days, 123I-IPPA SPECT myocardial imaging under fasting and nonfasting conditions. Patients were injected with 123I-IPPA (4-5 mCi) at rest with imaging performed at 4 (initial) and 30 (delay) min. For each image (initial and delay images), 10 segments were analyzed by three experienced observers without knowledge of patient identity or dietary condition using a 5-point grading system (O = no uptake to 4 = normal uptake). A summed global score was obtained for each image by adding the scores for all 10 segments. Image quality was assessed using a 3-point grading system.

RESULTS

Visual agreement for normal and abnormal segments between fasting and nonfasting conditions was 82% (kappa = 0.63). There were no significant differences in the summed global scores for both conditions. Image quality was equivalent for both conditions in 65% of cases and superior under the nonfasting condition in 25% of cases.

CONCLUSION

Image quality as well as the presence, location and severity of defects are similar under fasting and nonfasting conditions with 123I-IPPA. Therefore, fasting is not necessary before 123I-IPPA SPECT imaging for the assessment of myocardial viability.

Metastatic axillary lymph node technetium-99m-MIBI imaging in primary breast cancer

Technetium-99m-MIBI scintimammography has been shown to be useful in the detection of primary breast cancer. The purpose of this study was to evaluate the potential role of scintimammography in detecting axillary lymph node involvement in patients undergoing scintimammography to detect primary breast cancer.

METHODS

A group of 100 women with breast cancer who were scheduled for a Level I-II axillary dissection were prospectively studied. Scintimammography was performed in all patients before histopathologic confirmation of breast cancer. Two lateral (prone imaging) views and one anterior (supine) planar thoracic view were obtained 10-15 min after the injection of 25-30 mCi 99mTc-MIBI (10 min/view) by using a special breast positioning device (foam cushion) placed over the imaging table. Both of the axilla were included in the field-of-view. Two experienced blinded observers reviewed all cases both from films and from the computer screen with contrast adjustment when needed. The site of intravenous injection of 99mTc-MIBI was known to the interpreters in order to avoid reading any false-positive uptake in the axilla ipsilateral to the injection site.

RESULTS

A total of 52 patients had no axillary lymph node involvement (611 negative nodes) while 48 patients had at least one axillary lymph node with metastatic involvement (180/502 positive nodes). The sensitivity of scintimammography in detecting metastatic axillary lymph node involvement was 79.2% (38/48), and the specificity was 84.6% (44/52). The positive and the negative predictive values were 82.6% (38/46) and 81.5% (44/54), respectively.

CONCLUSION

This study shows that scintimammography has good diagnostic accuracy for detecting axillary lymph node involvement in patients with breast cancer. This information should be added to the result of standard scintimammography, which requires very minor modifications in order to simultaneously evaluate both of the axilla.

Cricopharyngeal myotomy for neurogenic oropharyngeal dysphagia

BACKGROUND

Forty patients (18 women, 22 men) with incapacitating oropharyngeal dysphagia of neurologic origin underwent cricopharyngeal myotomy. The subjective and objective response to myotomy was analyzed retrospectively with a mean postoperative follow-up of 48 months (range 1 to 255 months).

RESULTS

Radiologic evidence of functional obstruction caused by incoordination and incomplete relaxation of the upper esophageal sphincter was significantly reduced. Manometric recordings of resting and closing pressures of the upper esophageal sphincter were also significantly altered by the myotomy. Resting pressures decreased from 65 to 18 mm Hg and closing pressures dropped from 69 to 22 mm Hg. The relaxation time and poor coordination at the level of the upper esophageal sphincter, observed in the preoperative period, persisted after the operation. Radionuclide emptying studies in which a single liquid bolus was used showed persistent hypopharyngeal stasis with a 20% retention of radioactive material at 120 seconds. Subjectively, 33 patients initially had frequent aspiration episodes. Twenty became free of symptoms after myotomy (p < 0.01) and in six others the symptoms were improved. Overall, seven patients claimed to be free of symptoms of dysphagia and no longer had pharyngo-oral or pharyngonasal regurgitations and aspirations after their operation. Twenty-three other patients had improvement in symptoms. Ten patients reported no change in symptoms. All of them either were unable to swallow voluntarily or had dysarthria when assessed before the operation. One retropharyngeal hematoma is the only postoperative complication recorded. The operative mortality was 2.5% (1/40).

CONCLUSIONS

Cricopharyngeal myotomy palliates neurogenic oropharyngeal dysphagia in patients with intact oral-phase deglutition.

Comparative diagnostic accuracy of Tl-201 and Tc-99m sestamibi SPECT imaging (perfusion and ECG-gated SPECT) in detecting coronary artery disease in women

OBJECTIVES

This prospective study was conducted in 115 women to directly compare the sensitivity and specificity of thallium-201 (Tl-201), technetium-99m (Tc-99m) sestamibi perfusion and Tc-99m sestamibi electrocardiographic (ECG)-gated single-photon emission computed tomographic (SPECT) studies for detection of coronary artery disease (CAD).

BACKGROUND

Data on the comparative diagnostic accuracy of Tl-201 and Tc-99m sestamibi perfusion imaging for the detection of CAD, specifically in women, are very limited.

METHODS

Eighty-five patients with suspected CAD, scheduled for coronary angiography, and 30 volunteers with a pretest likelihood of < or = 5% for CAD were evaluated. Within 1 week, each patient underwent Tl-201 and Tc-99m sestamibi SPECT imaging procedures (both perfusion and gated SPECT imaging). Treadmill stress testing was used in 78 patients and dipyridamole in the remaining 37 patients. All images were interpreted by three observers in a blinded manner (consensus reading). Technetium-99m sestamibi SPECT studies were read without and then with ECG gating. Technetium-99m sestamibi gated SPECT studies were used to differentiate scar tissue from soft tissue attenuation artifact.

RESULTS

The overall sensitivities for detecting > or = 50% and > or = 70% stenoses were 75.0% and 84.3%, respectively, for Tl-201, and 71.9% and 80.4%, respectively, for Tc-99m sestamibi perfusion studies (p = 0.48). The specificity for lesions > or = 50% was 61.9% for Tl-201 and 85.7% for Tc-99m sestamibi perfusion (p = 0.07), whereas for lesions > or = 70% it was 58.8% for Tl-201 and 82.4% for Tc-99m sestamibi perfusion (p = 0.01). When the 34 patients with a normal coronary angiogram were added to the group of 30 normal volunteers, the "specificity" for lesions > or = 70% was 67.2% for Tl-201, 84.4% for Tc-99m sestamibi SPECT perfusion (p = 0.02) and 92.2% for Tc-99m sestamibi gated SPECT (p = 0.0004).

CONCLUSIONS

Both Tl-201 SPECT and Tc-99m sestamibi SPECT perfusion studies had a similar sensitivity for the detection of CAD in women. However, Tc-99m sestamibi SPECT perfusion imaging shows a significantly better specificity, which is further enhanced by the use of ECG gating.

Radionuclide captopril renography in postpartum renal artery aneurysms

We report the case of a young woman with three left renal artery aneurysms, diagnosed immediately postpartum, associated with a de novo high blood pressure. To assess anatomical and functional characteristics of renal artery aneurysms, renal angiogram, MRI, intravenous pyelography, ultrasonography and radionuclide renography were performed. Two patent saccular renal artery aneurysms were demonstrated in the left kidney by renal angiogram. A larger, thrombosed aneurysm was also depicted on the left side on ultrasonography, MRI and renal angiogram. The larger aneurysm was responsible for renovascular disease of the middle third of the kidney, as demonstrated by captopril and baseline radionuclide renographic studies. It also impeded drainage of the lower pyelocalyceal group, without obstructing it, as shown by concomitant furosemide (Lasix) evaluations.

Comparison between dipyridamole and adenosine as pharmacologic coronary vasodilators in detection of coronary artery disease with thallium 201 imaging

BACKGROUND

Both dipyridamole and adenosine are widely used as pharmacologic stressors with 201Tl imaging for detection of coronary artery disease. The purpose of this study was to compare dipyridamole and adenosine 201Tl imaging directly in patients with angiographically proved coronary artery disease.

METHODS AND RESULTS

Fifty-four patients were submitted to two planar 201Tl studies: one with dipyridamole and the other with adenosine. The interval between the two studies varied from 2 to 7 days and the order was assigned randomly. Three standard planar views were obtained 10 minutes and 4 hours after the injection of 3.0 mCi 201Tl. Administration of dipyridamole was as follows: 0.142 mg/kg/min during 4 minutes, followed by a slight exercise and 201Tl injection. The infusion of adenosine was as follows: 0.140 mg/kg/min during 6 minutes with injection of 201Tl after the third minute of infusion. Patients were asked to give their preference considering the number, type, severity, and duration of side effects on a scale from 0 (worst) to 5 (best). Reading was done by two experienced observers. The heart was divided into three segments per view. The change in systolic blood pressure was -12 +/- 11 mm Hg for adenosine and -5 +/- 10 mm Hg for dipyridamole (p < 0.001), and the change in heart rate was 18 +/- 10 beats/min for adenosine and 8 +/- 7 beats/min for dipyridamole (p < 0.001). With regions of interest, ischemic/normal wall ratios were determined: 0.78 +/- 0.06 for adenosine and 0.83 +/- 0.08 for dipyridamole (p < 0.001). Adenosine detected 295 normal, 170 ischemic, and 21 scar segments, whereas dipyridamole detected 326, 135, and 25 segments, respectively. Patients preferred adenosine (4.3 +/- 1.0 for adenosine vs 3.8 +/- 1.5 for dipyridamole; p < 0.04) mainly because of the short duration of side effects.

CONCLUSION

This study shows that the use of adenosine with 201Tl imaging may have some advantages over dipyridamole.

"Cold" reflex sympathetic dystrophy in an adult

The classical presentation of acute reflex sympathetic dystrophy (RSD) or triple-phase bone scintigraphy usually consists of increased periarticular uptake in each phase. The authors present a rare case of acute adult RSD characterized by bone hypofixation of Tc-99m MDP. Reflex sympathetic dystrophy in adults and children is reviewed.

Uncut Collis-Nissen gastroplasty: early functional results

BACKGROUND

This study reviewed the short-term results of the uncut Collis-Nissen gastroplasty.

METHODS

From 1990 through 1993, 27 consecutive patients (16 men, 11 women) underwent an uncut Collis-Nissen gastroplasty. Mean age was 59 years (range, 30 to 75 years). Three patients had a previous failed antireflux procedure. Indications for operation were gastroesophageal reflux disease resistant to medical treatment in 18 patients and symptomatic hiatal hernia in 9 patients. Fourteen patients had Barrett's esophagus and 4 had a peptic stricture. Complete esophageal function testing including barium swallow, endoscopy, manometry, and 24-hour pH recording was performed in 26 of 27 patients preoperatively and postoperatively.

RESULTS

Five patients (19%) had complications, which included atelectasis in 2, cardiac dysrhythmia in 2, and prolonged ileus in 1. There were no operative deaths. Follow-up was complete in all patients and ranged from 8 to 45 months (mean, 22 months). Subjectively, symptoms of reflux were resolved in all patients. Six patients complain of slow esophageal emptying and 3 have occasional episodes of dysphagia. None required postoperative dilation. Ulcers and erosions healed in all 26 patients who underwent endoscopy but recurred in 2 at 21 and 36 months postoperatively. Mean lower esophageal sphincter gradient increased from 8.3 mm Hg preoperatively to 14.6 mm Hg (p = 0.0001). Total percent of acid exposure decreased from 8.0% preoperatively to 1.7% (p = 0.003).

CONCLUSIONS

We conclude that the uncut Collis-Nissen procedure provides acceptable short-term control of gastroesophageal reflux disease.

Technetium-99m-sestamibi prone scintimammography to detect primary breast cancer and axillary lymph node involvement

The purpose of this study was to evaluate prospectively the sensitivity and specificity of scintimammography in the detection of both primary breast cancer and axillary lymph node involvement.

METHODS

Sixty-five consecutive women referred for a suspicious breast lesion on clinical examination and/or with abnormal mammographies suggestive of malignancies were studied with scintimammography using planar prone imaging (with a chest positioning device with semicircular lateral aperture on the imaging table) performed 15 min postinjection of 25-30 mCi 99mTc-sestamibi. Three planar views, right and left lateral prone and anterior supine thoracic views, were obtained (8-10 min/view). The entire breast and ipsilateral axillary region were included in the field of view. Excisional breast biopsy and/or fine needle aspiration cytology were performed in all patients within 4 wk after scintimammography. Axillary node dissection was also performed.

RESULTS

The largest primary tumor measured 2 x 3 cm. There were 47 primary breast cancers (8 different histologic types) and 18 benign breast lesions (5 histologic types). The sensitivity of scintimammography for detecting primary breast cancer was 91.5% (43 true-positive, 4 false-negative) and the specificity was 94.4% (17 true-negative, 1 false-positive). Metastatic axillary lymph node involvement was seen in 19 of 41 patients. The sensitivity of scintimammography to detect metastatic lymph nodes was 84.2% (16 true-positive, 3 false-negative) and the specificity was 90.9% (20 true-positive, 2 false-positive).

CONCLUSION

This preliminary study confirms the results of some previous reports, which showed the high diagnostic accuracy of scintimammography in detecting breast cancer. This study also shows the potential value of this procedure to detect axillary lymph node involvement as concomitant information.

Technetium-99m antimyosin antibody (3-48) myocardial imaging: human biodistribution, safety and clinical results in detection of acute myocardial infarction

Technetium-99m antimyosin (99mTc-AM) antibody imaging may have significant advantages over indium-111 antimyosin in clinical practice. The purpose of this study was to determine the human biodistribution, the safety profile and the sensitivity of 99mTc-AM (3-48) imaging in the detection of both Q-wave and non-Q-wave myocardial infarction (MI). Biodistribution and safety parameters were mainly determined in 12 normal healthy volunteers while 40 patients with proven MI (22 Q-wave, 18 non-Q-wave) were injected with 99mTc-AM (20-25 mCi) between 5 h and 7 days after the onset of acute chest pain. Three standard planar views were performed at 6 h and at 24 h post injection. Both sets of images were completed in 33 patients while two patients were imaged only at 6 h, three patients only at 18 h and one at 18 and 24 h. One patient was not imaged. Vital signs and ECG were recorded and blood samples for haematology, biochemistry and human antimurine antibodies (HAMA) and urinalysis were obtained in all volunteers and patients. No serious adverse reactions or side-effects attributable to 99mTc-AM have been reported. No volunteers or patients developed allergic reactions or significant increases in HAMA titres. Reading of 99mTc-AM imaging was performed by two blinded experienced observers. The sensitivity of 99mTc-AM in the detection of MI was 100% (21/21) for Q-wave and 83.3% (15/18) for non-Q-wave infarctions. The overall sensitivity was 92.3% (36/39). The three false-negative cases were inferoposterior MI. A certain degree of uptake focalization was seen in 26 out of 35 (74.2%) at 6 h. At 24 h, two patients (5.8%) did not show 99mTc-AM uptake while 22 (64.7%) showed intense focal uptake, seven (20.6%) moderate uptake and 3 (8.9%) slight uptake. It is concluded that 99mTc-AM (3-48) imaging is safe and shows high sensitivity in the detection of both Q-wave and non-Q-wave MI even with early imaging (6 h post injection). These promising results warrant further clinical investigation.

A physiologic approach to renal scintigraphy. Application to evaluation of hypertension

The aim of this study was to define the use of the triple radiopharmaceutical renal study (TRRS) for renal scintigraphy as a physiological tool for renal evaluation, and to determine if the sensitivity and/or specificity of a renal study for the diagnosis of renovascular hypertension (RVH) could be improved by the combination of three radiopharmaceuticals (i.e., I-131 OIH, Tc-99m DTPA, and Tc-99m glucoheptonate). One hundred ninety-five patients with suspected RVH underwent TRRS, standard Tc-99m DTPA renal studies, and renal angiography. One hundred eighty-nine patients were hypertensive and ischemic nephropathy was suspected in six. Ninety-one, including three patients with ischemic nephropathy, had a renal artery stenosis of 70% or more (66 unilateral, 25 bilateral). Effective renal plasma flow (ERPF), glomerular filtration rate (GFR) (from plasma clearance of I-131 OIH and Tc-99m DTPA), and geometric renal masses (from Tc-99m glucoheptonate study) were compared to normal values corrected for body surface, to determine the severity of renal dysfunction. For the TRSS, RVH criteria included: 1) differential Tc-99m DTPA function minus differential Tc-99m glucoheptonate function of affected kidney ( < -5% or > 5%) and 2) functional parameters: ERPF = 1.6-2.0 ml/g/minute, GFR = 0.25-0.4 ml/g/minute, and filtration fraction (i.e., GFR/ERPF = 0.15-0.20) on the affected side.

Northern exposure: nuclear cardiology in the Canadian health care system

The Canadian health care system may provide valuable insights into the future practice of nuclear cardiology in the United States. Rationing of medical care is not legislated by the Canadian health care system, although resource allocation is required of Canadian physicians and hospital administrators. Canadian nuclear cardiologists and physicians are not restricted in the ordering of diagnostic studies, despite the decreased availability in imaging systems and the centralization of equipment and personnel in Canada. Canadian imaging equipment is, in general, used more with less average idle time per unit. Delays in the performance of nonemergent imaging studies are more common in Canadian imaging laboratories. The number of out-of-hospital nuclear medicine laboratories is not increasing, because of government constraints on licensing and the general requirement that only radiologists or certified nuclear medicine physicians can operate these laboratories. A survey of 71 nuclear cardiology laboratories in the United States and Canada reveal that 21% of all cardiac imaging studies are performed for post-myocardial infarction risk stratification in Canada, compared with only 11% in United States laboratories. Rest and reinjection thallium imaging studies are performed more than twice as often in the United States laboratories. Canadian laboratories perform a higher average number of myocardial perfusion (2123 vs 1789) and ventricular function (773 vs 554) studies as compared with their United States counterparts. No other significant differences in clinical usage patterns were identified. A total of 130,000 nuclear cardiologies were performed in Canada in 1993, with less than 5% growth in the number of Canadian studies projected for 1994. Forty-five percent of Canadian perfusion studies are performed with 99mTc-labeled sestamibi frequently using a 2-day protocol (60%) with electrocardiogram gating (30%). Positron emission tomography (PET) can be performed in only six Canadian cities. Canadian PET centers are government funded, located in university teaching hospitals, and principally used for the purpose of research. Stress echocardiography is not widely performed in Canada because of the heavy clinical volume of standard echocardiographic studies at most hospitals, which reduces the time available for stress echocardiography. No separate billing code is available for stress echocardiography studies in Canada. Canadian cardiologists have accepted the value of rest and stress nuclear studies for the management of their patients and have concluded that it is more time efficient to perform clinical duties in lieu of stress echocardiographic studies. In conclusion, the realities of the Canadian health care system are that universal health care is valuable as long as it is consistent high quality medical care, and that the cost of universal coverage must be borne by the taxpayer using the system. The fact that nuclear cardiology has continued to thrive in the Canadian health care system suggests that future health care modifications in the United States will not exert a significant impact on the practice of nuclear cardiology.

Myocardial technetium 99m-labeled sestamibi single-photon emission computed tomographic imaging in the detection of coronary artery disease: comparison between early (15 minutes) and delayed (60 minutes) imaging

BACKGROUND

Previous studies have demonstrated that there is a "partial" myocardial redistribution of 99mTc-labeled sestamibi (MIBI) between 1 and 3 hours after intravenous injection at stress. The purpose of this prospective study was to compare MIBI single-photon emission computed tomographic (SPECT) imaging performed 15 and 60 minutes after the injection at stress in the detection of coronary artery disease.

METHODS AND RESULTS

Thirty-five patients with coronary artery disease (26 underwent coronary angiography and 23 had a positive 201Tl study result) were included in this study. SPECT imaging started 15 minutes after the injection of 25 to 30 mCi MIBI at peak stress (180-degree arc, 32 angles, 25 sec/view, and high-resolution collimator). Patients underwent reimaging at 60 minutes according to the same protocol and with the same gamma camera. A rest study was obtained 75 minutes after the injection of MIBI (25 to 30 mCi) at rest, 48 hours later. Images (divided for a total of 19 segments per patient) were interpreted by two blinded observers for patient diagnosis and segmental comparison. The patient diagnosis was the same for the two protocols: normal = 3, ischemia = 27, and scar = 5. The segmental agreement (kappa = 0.90) was 632/665 (95.0%). The imaging performed at 15 minutes detected normal, ischemia, and scar in 413, 189, and 63 segments, respectively, whereas the imaging performed at 60 minutes detected 422, 180, and 63 segments, respectively (difference not significant). The early and delayed images were placed side by side for subjective comparison of the extent of the defect. Early imaging showed slightly larger defects in six patients, equal defects in 24 patients, and slightly smaller defects in five patients. Ischemic/normal wall ratios were 0.67 +/- 0.16 at 15 minutes and 0.68 +/- 0.15 at 60 minutes.

CONCLUSIONS

There is no clinically significant difference between SPECT imaging performed at 15 minutes or 60 minutes after the injection of MIBI at stress. Furthermore, this study showed that it is feasible to obtain good-quality MIBI images even 15 minutes after the injection at stress.

Thallium-201-dipyridamole imaging: comparison between a standard dose and a high dose of dipyridamole in the detection of coronary artery disease

The purpose of this study was to compare two different doses of dipyridamole as a pharmacologic stress test for 201Tl imaging.

METHODS

Twenty-four patients with significant coronary artery disease (15 had undergone a coronary angiogram and 9 had undergone a previous 201Tl study with a significant lesion) were prospectively studied. Within 1 wk, all patients underwent two 201T-dipyridamole myocardial planar studies, one using a standard dose (STD) and the other, a high dose (HIGH) of dipyridamole. The protocol order was randomly assigned. The STD protocol used a dose of 0.14 mg/kg/min for a duration of 4 min (0.56 mg/kg), and the HIGH protocol used a dose of 0.14 mg/kg min for a duration of 6 min (0.84 mg/kg). The 201Tl was injected 3 min after the end of the dipyridamole infusion. Images, obtained 5 min and 4 hr later, were interpreted (divided into five segments each) by three blinded observers.

RESULTS

The STD protocol showed normal, ischemia and scar in 252, 91 and 17 segments, respectively. The HIGH protocol detected 232, 118 and 10 segments, respectively. A side-by-side evaluation was done to evaluate the defect extent subjectively, which was greater with HIGH in 14, equal in six and smaller in four patients. One or more side effects were seen in 14 patients with STD and in 19 with HIGH. Increased heart rate (8 bpm for STD and 19 bpm for HIGH, p < 0.001) was the only significant change seen in the hemodynamic parameters.

CONCLUSION

This preliminary study indicates that a high dose of dipyridamole seems to be safe and can be helpful to increase the sensitivity of 201Tl imaging.

Antireflux operations in patients with scleroderma

Fourteen patients with scleroderma underwent antireflux operations (10 short Nissen, 2 Collis-Nissen, 1 Collis-Belsey, and 1 vagotomy and antrectomy with Roux-en-Y). Esophageal function was assessed preoperatively and postoperatively with a follow-up range of 8 to 181 months (mean, 65 months). Reflux symptoms were relieved in 10 of the 14 patients (p < 0.01), as shown by a decrease in their 24-hour acid exposure of from 15% to 7.5% (p < 0.05). However, the lower esophageal sphincter pressure gradient created by the operations did not increase significantly (3.7 +/- 3.4 mm Hg to 5.5 +/- 3.5 mm Hg). The esophageal acid exposure decreased sufficiently to promote some alleviation of the esophagitis. Radiologic signs of stenosis regressed in 6 of 7 patients. Postoperative endoscopic assessment revealed complete or partial healing of erosions seen preoperatively in 6 of the 7 patients so studied, and healing of all ulcers in 3 patients. Twelve patients continued to have columnar metaplasia. Manometric studies disclosed no significant changes in propulsion and contractility. Distal esophageal resting pressures rose significantly from 6.2 to 9.4 mm Hg (p < 0.05 mm Hg), suggestive of stasis. Radionuclide transit studies, however, showed no significant decrease in the esophageal emptying capacity after operation. It is concluded that conventional antireflux operations in patients with scleroderma can palliate reflux damage without jeopardizing esophageal function.

Detection of myocardial necrosis and inflammation by nuclear cardiac imaging

For almost two decades, Tc-99m pyrophosphate has been the preferred infarct-avid imaging agent in nuclear cardiology. More recently, Indium-III- and Tc-99m-labeled antimyosin monoclonal antibody imaging have been extensively investigated. Although In-III antimyosin is not yet available in North America, this radioimmunoscintigraphic procedure is very promising for detection of both Q-wave and non-Q-wave myocardial infarction, especially when other standard diagnostic modalities fail to be contributive. When appropriately applied, radionuclide imaging with infarct-avid agents may provide very helpful clinical information.

Long-term effect of total fundoplication on the myotomized esophagus

From 1978 to 1983, 17 patients had an esophagocardiomyotomy with an added short total fundoplication as an antireflux procedure. Thirteen had achalasia and 4, diffuse esophageal spasm. All patients initially had the usual symptoms of these motor disorders. Early after the operation all became asymptomatic, but over the years of follow-up, symptoms reappeared in 14 of 17 patients, and 5 required reoperation. The distal esophageal transverse diameter showed progressive dilatation from 3.9 cm preoperatively to more than 6 cm after 10 years of evolution. Over the same period, deterioration in the esophageal emptying capacity caused esophageal stasis to increase from 32% to 75%. Manometric changes were significant after the operation: resting pressures in the esophageal body decreased from 10.5 to 4.4 mm Hg (p < 0.001) proximally and from 12.2 to 4.6 mm Hg distally (p < 0.001). Peak contraction pressures became significantly weaker: 38 to 30 mm Hg in the proximal esophagus (p < 0.001) and from 49.2 to 28.1 in the distal esophagus (p < 0.001). Tertiary contractions were unchanged distally, but peristalsis reappeared in more than 30% of all swallows in the proximal half of the esophageal body. The resting pressure gradient in the lower esophageal sphincter area was reduced from 25.5 to 7.4 mm Hg by the operation. This gradient remained stable over 10 years of follow-up. No significant acid exposure was documented in 8 patients undergoing 24-hour pH recordings after their operation. Endoscopy revealed dilatation and retention without evidence of reflux esophagitis damage. Total fundoplication when associated with esophageal myotomy results in improved symptoms in the early postoperative phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric inhibitory polypeptide-dependent cortisol hypersecretion--a new cause of Cushing's syndrome

BACKGROUND

Corticotropin-independent nodular adrenal hyperplasia is a rare cause of Cushing's syndrome, and the factors responsible for the adrenal hyperplasia are not known.

METHODS

We studied a 48-year-old woman with Cushing's syndrome, nodular adrenal hyperplasia, and undetectable plasma corticotropin concentrations in whom food stimulated cortisol secretion.

RESULTS

Cortisol secretion had an inverse diurnal rhythm in this patient, with low-to-normal fasting plasma cortisol concentrations and elevated postprandial cortisol concentrations that could not be suppressed with dexamethasone. The cortisol concentrations increased in response to oral glucose (4-fold increase) and a lipid-rich meal (4.8-fold increase) or a protein-rich meal (2.6-fold increase), but not intravenous glucose. The infusion of somatostatin blunted the plasma cortisol response to oral glucose. Intravenous infusion of gastric inhibitory polypeptide (GIP) for one hour increased the plasma cortisol concentration in the patient but not in four normal subjects. Fasting plasma GIP concentrations in the patient were similar to those in the normal subjects; feeding the patient test meals induced increases in plasma GIP concentrations that paralleled those in plasma cortisol concentrations. Cell suspensions of adrenal tissue from the patient produced more cortisol when stimulated by GIP than when stimulated by corticotropin. In contrast, adrenal cells from normal adults and fetuses or patients with cortisol-producting or aldosterone-producing adenomas responded to corticotropin but not to GIP.

CONCLUSIONS

Nodular adrenal hyperplasia and Cushing's syndrome may be food-dependent as a result of abnormal responsiveness of adrenal cells to physiologic secretion of GIP. "Illicit" (ectopic) expression of GIP receptors on adrenal cells presumably underlies this disorder.

Detection and localization of parathyroid adenomas in patients with hyperparathyroidism using a single radionuclide imaging procedure with technetium-99m-sestamibi (double-phase study)

Dual radionuclide imaging using a combination of 201Tl with either 99mTcO4- or 123I is recognized as a useful procedure in the preoperative localization of parathyroid adenomas. Recently, 99mTc-sestamibi (MIBI) has been introduced for myocardial perfusion imaging as an alternative to 201Tl. The purpose of this prospective study was to evaluate parathyroid scan using early and late imaging following MIBI injection. Twenty-three patients (21 F, 2 M, mean age: 57 yr) with a clinical and biologic diagnosis of hyperparathyroidism were submitted to a MIBI study prior to surgical exploration of the neck. Cervico-thoracic planar imaging (anterior view, 10 min/view) was performed at 15 min and at 2-3 hr after an intravenous injection of 20-25 mCi of MIBI. A positive MIBI scan for parathyroid adenoma was defined as an area of increased focal uptake which persisted on late imaging, contrary to the uptake in the normal thyroid tissue which progressively decreases over time (differential washout). Surgical exploration of the neck, performed between 1 day and 72 days (average: 16 days) after the MIBI study, showed a parathyroid adenoma in 21 patients and hyperplasia in two patients. MIBI scan correctly detected and localized 19/21 adenomas (90%). In conclusion, parathyroid imaging using a single radionuclide with MIBI (early and late study with differential washout analysis) is a promising procedure in the preoperative detection and localization of parathyroid adenomas in patients with primary hyperparathyroidism.

New agents labelled with technetium 99m for myocardial perfusion imaging

New agents labelled with technetium 99m (99mTc) are now available for myocardial perfusion imaging. In this article the author reviews the biologic characteristics, the imaging protocols and the clinical usefulness of thallous chloride Tl 201, 99mTc-sestamibi and 99mTc-teboroxime (not yet available in Canada), as well as their complementary roles in the detection of coronary artery disease.

Comparison between thallium-201, technetium-99m-sestamibi and technetium-99m-teboroxime planar myocardial perfusion imaging in detection of coronary artery disease

Technetium-99m-sestamibi (MIBI) and 99mTc-teboroxime (TEBO) are two new myocardial perfusion imaging agents. The purpose of this prospective study was to compare MIBI and TEBO to 201TI planar imaging. Eighteen patients with significant coronary artery disease on coronary angiogram were submitted to three treadmill stress tests performed within 3 mo and were imaged with the three radiopharmaceuticals as follows. 1. TI: 2.2 mCi, immediate and delayed views (4 hr later, 8 min/view). 2. TEBO: 15-20 mCi at stress (1 min/view) and a second injection was repeated 4 hr later at rest (20-25 mCi). 3. MIBI: 15-18 mCi at stress (8 min/view) and 1-4 days later, 15-18 mCi at rest. Patients achieved similar levels of exercise. A blinded reading was performed by three observers. The left ventricle was divided into three segments/view and ischemic/normal wall ratios were also determined. Segmental comparison showed an agreement in 85% (138/162) of the segments between TI and TEBO, in 92% (149/162) between TI and MIBI and in 84% (136/162) between MIBI and TEBO. Abnormal TI, MIBI and TEBO studies were seen in 16 (89%), 16 (89%) and 15 (83%) patients, respectively, detecting 77, 75 and 65 abnormal segments. Ischemic-to-normal wall ratios were 0.75 +/- 0.06, 0.73 +/- 0.08 and 0.78 +/- 0.08 for TI, MIBI and TEBO, respectively. In conclusion, although the biologic characteristics of these agents are different, this study showed a good correlation between them in detection of significant coronary artery disease (high pretest likelihood population).

Blinded evaluation of planar technetium-99m-sestamibi myocardial perfusion studies

Sestamibi planar myocardial perfusion studies were performed at Hotel-Dieu de Montreal on 28 patients with documented coronary artery disease and 16 normal subjects. Stress and rest studies were performed on separate days. These studies were sent to Virginia for interpretation while blinded as to age, sex, and other clinical information. Studies were quantitated independently by two operators (using a computer program modified for Sestamibi), and interpreted independently by two experienced interpreters. Computer quantitation of 2816 segments gave an average interoperator deviation of 2.2%. Pure quantitative criteria were applied for computer interpretation. By varying the detection threshold, we produced the entire ROC curve relating sensitivity and specificity as a function of detection threshold. Using only computer criteria for normal or abnormal, interoperator agreement by patient was 98% and 93% by view. The computer could achieve equal positive and negative predictive accuracy of 87%. Interpreters, allowed both quantitative and subjective judgment, agreed on 91% of 44 patients, 90% of 132 views, and 92% of 660 segments. Interpreters averaged 94% positive and 86% negative predictive accuracy.

Comparison between technetium-99m-teboroxime and thallium-201 dipyridamole planar myocardial perfusion imaging in detection of coronary artery disease

Technetium-99m (TC-99m)-teboroxime is a new myocardial perfusion imaging agent. The purpose of this prospective study was to compare Tc-99m-teboroxime with thallium-201 imaging after the administration of dipyridamole. Thirty patients referred for the evaluation of chest pain were studied with both thallium-201 and Tc-99m-teboroxime dipyridamole scans (mean interval 2 days). Dipyridamole was administered at 0.142 mg/kg/min for 4 minutes. Planar imaging (3 standard views) was obtained at 5 and 240 minutes after the injection of 2.2 mCi of thallium-201. Tc-99m-teboroxime (18 to 25 mCi) was injected after dipyridamole infusion. A second injection, at rest, was repeated 4 hours later. Planar imaging (3 standard views of 1 minute/view for the first 2 views, and 90 seconds for the last view) was obtained 2 minutes after Tc-99m-teboroxime injection. Blinded reading was performed by 3 observers. Thallium-201 showed perfusion defects in 182 myocardial segments corresponding to 33 of 45 (73%) significantly stenosed coronary arteries (greater than or equal to 70% reduction in endoluminal diameter), and Tc-99m-teboroxime detected 160 abnormal segments corresponding to 29 of 45 (64%) stenosed arteries. Thallium-201 and Tc-99m-teboroxime studies were normal in 3 patients. In conclusion, this study shows that there is a good correlation in the imaging results found with thallium-201 and Tc-99m-teboroxime using dipyridamole infusion on both a segmental and a diagnostic comparison.

Technetium-99m-sestamibi myocardial perfusion imaging in detection of coronary artery disease: comparison between initial (1-hour) and delayed (3-hour) postexercise images

Technetium-99m-sestamibi, a new myocardial perfusion imaging agent, does not show significant or rapid myocardial redistribution following its intravenous injection at stress. The purpose of this study was to evaluate the myocardial clearance of 99mTc-sestamibi and ischemic/normal wall ratios at 1 hr and at 3 hr after injection at stress in patients with significant coronary artery disease. Twenty-five patients with ischemic defects on 201Tl scans (n = 15) and/or significant disease on coronary angiogram (n = 18) were prospectively studied. Planar images were obtained at 65 and at 190 min after an injection at stress of 20-25 mCi of 99mTc-sestamibi. A rest study was performed 1-6 days later. Ischemic/normal wall ratios were 0.73 +/- 0.10 and 0.83 +/- 0.12 (p less than 0.05) at 1 and 3 hr, respectively (0.98 +/- 0.15 at rest). Myocardial washout was 26% +/- 12% for normal walls and 15% +/- 8% for ischemic walls (p less than 0.001). Segmental analysis showed 48 and 46 ischemic segments at 1 and 3 hr, respectively. In conclusion, although only a few ischemic segments were missed at 3 hr, significantly lower ischemic/normal wall ratios were found at 1 hr. Faster myocardial washout from normal walls is responsible for the partial reduction of this ratio.

Technetium 99m SESTAMIBI myocardial perfusion imaging: comparison between treadmill, dipyridamole and trans-oesophageal atrial pacing "stress" tests in normal subjects

The purpose of this study was to determine the blood clearance, myocardial uptake and heart/lung and heart/liver ratios of technetium 99m methoxyisobutylisonitrile (99mTc-SESTAMIBI) following 3 different types of cardiac stimulation in normal subjects: treadmill stress (STRESS), intravenous administration of dipyridamole (DIP) and trans-oesophageal atrial pacing (TAP). Ten normal volunteers were submitted to 3 injections of 99mTc-SESTAMIBI (10 mCi/70 kg, separated by an interval of 7 days) following STRESS (standard Bruce protocol), DIP (0.142 mg/kg.min during 4 min) and TAP procedures. Blood samples were collected from 1 to 60 min after each 99mTc-SESTAMIBI injection. Planar imaging was performed at 5, 30 and 60 min. Blood retention (percentage of injected dose at 1 min) was 56% +/- 4%, 24% +/- 4% and 38% +/- 6% for STRESS, DIP and TAP, respectively (P less than 0.001). Myocardial uptake was similar for the 3 procedures while the heart lung ratio at 60 min was 3.1 +/- 0.5, 3.8 +/- 0.6 and 3.2 +/- 0.5 for STRESS, DIP and TAP, respectively. Heart/liver ratio at 60 min was 1.9 +/- 0.5, 1.3 +/- 0.3 and 1.1 +/- 0.2 for STRESS, DIP and TAP, respectively (P less than 0.001). These results demonstrated that the 3 types of cardiac stimulation show good imaging parameters with 99mTc-SESTA-MIBI.

Radionuclide esophageal transit study in detection of esophageal motor dysfunction: comparison with motility studies (manometry)

Radionuclide esophageal transit study (RETS) has been developed to assess motor function of the esophagus. The purpose of this study was to compare RETS to esophageal motility studies (EMS) in detection of motility disorders. A total of 109 consecutive patients without previous history of surgery on the esophagus underwent both RETS and EMS within one month of each other. Final diagnosis was divided into three categories: I--primary esophageal motor disorders (n = 39); II--reflux disease (n = 48); and III--non-cardiac chest pain and/or dysphagia (n = 22). Using EMS as the standard, the results of RETS were as follows: sensitivity for detection of motor dysfunction was 97%, 92%, and 77% for Groups I, II, and III, respectively, while specificity was 91% for Group II and 100% for Group III. Global sensitivity was 92% and specificity was 88%. No clinically significant motor disorders were missed by RETS. In conclusion, RETS is a useful noninvasive test for the screening of patients with symptoms thought to be of esophageal origin.

[Comparison between myocardial perfusion scintigraphy with thallium-201 and technetium-99m-Sestamibi (methoxy isobutyl isonitrile) for the detection of coronary atherosclerotic disease]

99mTc-SESTAMIBI is a new myocardial perfusion agent used in the detection of atherosclerotic coronary artery disease. In the present study, myocardial scintiscanning (on treadmill) with 99mTc-SESTAMIBI and 201-Thallium were compared, and both were compared with coronary angiography. Some 130 consecutive patients were evaluated within an interval of a few weeks with scintiscans of both 99mTc-SESTAMIBI and 201-Thallium: 82 of them were also examined by coronary angiography. Segmental analysis of the two series of scans revealed some correlation in 89.2% of the segments, while correlation of the final diagnosis showed agreement in 92% of cases. Compared to coronary angiography, sensitivity in the detection of CAD was found to be 75.8% for 201-Thallium and 72.5% for 99mTc-SESTAMIBI. The authors conclude that 99mTc-SESTAMIBI is a promising myocardial perfusion agent which displays an excellent correlation with 201-Thallium.

Technetium-99m sestamibi myocardial imaging: same-day rest-stress studies and dipyridamole

Unlike thallium-201, technetium-99m (Tc-99m) sestamibi does not redistribute in the myocardium after injection. Thus, 2 separate injections, 1 at rest and the other at stress (or after dipyridamole), are required to differentiate ischemia from scar. From a physical viewpoint, a 24-hour interval between the 2 injections is preferable for detection of coronary artery disease (CAD) with Tc-99m sestamibi imaging. However, same-day studies are more convenient in clinical practice. Results of studies using different Tc-99m sestamibi injection protocols are presented with emphasis on the advantages of a rest-stress injection sequence with a low dose at rest (7 mCi) followed 2 hours later by a higher dose at stress (25 mCi). A prospective study was conducted in a patient population with proven CAD using same-day studies to compare a rest-stress (7 and 25 mCi, respectively) to a stress-rest (7 and 25 mCi) Tc-99m sestamibi injection sequence. There was an agreement in 87.3% of the analyzed segments between the 2 protocols. However, the largest discordance for type of defect applied to 7.4% of the segments judged ischemic in the rest-stress protocol, which were called scars on stress-rest. This study showed that a rest-stress sequence is preferable when using a same-day protocol with a short time interval (less than 2 hours) between the 2 Tc-99m sestamibi injections because the rest image performed initially represents a "true" rest study, which is not necessarily the case with the stress-rest sequence. Preliminary studies were performed to evaluate dipyridamole with Tc-99m sestamibi imaging in normal subjects and in patients with CAD. These studies showed that treadmill and dipyridamole Tc-99m sestamibi imaging are comparable and the results are similar to those obtained with thallium-201.

Characterization of technetium-99m-L,L-ECD for brain perfusion imaging, Part 2: Biodistribution and brain imaging in humans

The safety, biodistribution and kinetics of a new perfusion imaging agent [99mTc-L,L]-ethyl cysteinate dimer (ECD) was evaluated in normal volunteers. Technetium-99m-L,L-ECD is a neutral, lipophilic complex, which is radiochemically pure and stable. Twelve healthy adults were injected with 25-30 mCi of 99mTc-L,L-ECD and imaged periodically for up to 24 hr. Planar imaging showed rapid brain uptake with a peak concentration of 4.9% injected dose and very slow brain washout (approximately 6% per hour during the first 6 hr). Repeat or dynamic tomographic imaging of the brain using either a rotating gamma camera or a multidetector system was performed up to 6 hr postinjection. The distribution of 99mTc-L,L-ECD in the brain did not change and was similar to the pattern seen with other perfusion agents. Background facial areas and lungs cleared rapidly. Peak blood activity was below 10% injected dose at all times and 99mTc-L,L-ECD cleared rapidly through the kidneys. Vital signs, blood and urine chemistries were normal in all volunteers and no adverse reactions were noted. These results suggest that 99mTc-L,L-ECD should be useful for routine assessment of cerebral perfusion in humans.

Clinical comparison between thallium-201 and Tc-99m-methoxy isobutyl isonitrile (hexamibi) myocardial perfusion imaging for detection of coronary artery disease

99mTc-hexamibi (methoxy isobutyl isonitrile) is a new 99mTc-hexakis analog that can be used as a myocardial perfusion imaging agent. The purposes of this study were to compare 99mTc-hexamibi to 201Tl-thallous chloride myocardial stress scintigraphy in patients referred for investigation of chest pain and to evaluate the sensitivity of 99mTc-hexamibi in detection of coronary artery disease. One hundred patients were prospectively studied with both 201Tl and 99mTc-hexamibi planar imaging. Sixty five patients had a current coronary angiography. There was a total of 97 significantly (less than or equal to 70%) stenosed major coronary arteries. 99mTc-hexamibi (25 mCi) study was done within a week of the 201Tl scan with similar double products upon standard treadmil stress testing. Rest studies with 99mTc-hexamibi were obtained 24-48 h after the stress test using the same acquisition parameters and dose. Analysis was performed blind by three observers. The left ventricle was divided into five segments in each image. Analysis of 201Tl and 99mTc-hexamibi results in 1500 left ventricle segments showed an overall agreement in 1326/1500 (88.4%) segments. Correlation between the patient diagnosis on the 201Tl and 99mTc-hexamibi studies showed an agreement in 89 patients (89%). 201Tl revealed myocardial uptake defects in 526 segments, detecting 72 out of 97 (74.2%) significantly stenosed coronary arteries and 99mTc-hexamibi detected 513 segments corresponding to 68 (70.1%) stenosed arteries (no significant statistical difference). In conclusion, these results show a good correlation between 201Tl and 99mTc-hexamibi myocardial imaging in the detection of significant coronary artery disease.

Same day injections of Tc-99m methoxy isobutyl isonitrile (hexamibi) for myocardial tomographic imaging: comparison between rest-stress and stress-rest injection sequences

It has been shown that both rest and stress 99mTc-hexamibi myocardial perfusion imaging can be performed on the same day using two different doses injected within few hours (the first one at rest followed by a second at stress). In order to evaluate and compare 2 sequences (rest-stress and stress-rest) of 99mTc-hexamibi injections performed the same day, 18 patients with either abnormal 201Tl myocardial scan or abnormal coronary angiography were studied with 2 99mTc-hexamibi injections protocols. The rest-stress study was performed as follows: 7 mCi 99mTc-hexamibi was injected at rest. Single photon emission computed tomography (SPECT) was performed 60 min later. Immediately after the rest study, patients were injected at peak stress with 25 mCi 99mTc-hexamibi. Tomographic imaging was repeated 1 h later. Patients were submitted to the stress-rest protocol within 3 days. Tomographic imaging was done 1 h after a 7 mCi injection at stress. This study was followed by an injection of 25 mCi 99mTc-hexamibi at rest, a tomographic study was performed 60 min later. Myocardial sections were reconstructed in horizontal long, vertical long, and short axes. Data analysis also included polar map representation. A total of 324 segments were interpreted blind by 3 observers, there was an agreement in 283/324 (87.3%) segments between the 2 protocols. However, 24 segments (7.4%) judged ischemic on rest-stress were called scars on stress-rest.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial perfusion imaging with a new radiotracer, technetium-99m-hexamibi (methoxy isobutyl isonitrile): comparison with thallium-201 imaging

Technetium-99m-hexamibi (methoxy isobutyl isonitrile) is a Tc-99m-hexakis analog that can be used as a myocardial perfusion imaging agent. This is a report of an initial study that was performed in four institutions to assess the feasibility of Tc-99m-hexamibi myocardial imaging for the detection of coronary artery disease in patients undergoing treadmill stress test. Thirty-three patients referred for evaluation of chest pain had two exercise stress tests, one with Tl-201 and at least 24 hours after, and a second one with Tc-99m-hexamibi. Myocardial planar imaging started 60 minutes after injection at stress of 10-20 mCi of Tc-99m-hexamibi. Because this agent does not redistribute in myocardium after a stress injection, a second injection of 10-20 mCi of Tc-99m-hexamibi was performed with the patient at rest a few days later. Qualitative assessment of both Tl-201 and Tc-99m-hexamibi myocardial distribution was performed in 297 left ventricle segments (three segments of each of three views). There was a good correlation for the presence of normality, scar, or ischemia with the two radiopharmaceuticals, both on a segment by segment (259/297, or 87.2%) and patient-by-patient basis (29/33, or 87.9%). The number of segments found ischemic with Tl-201 and with Tc-99m-hexamibi were nearly equal, as were the number that were normal with one radiopharmaceutical and ischemic by the other. This initial study demonstrates that it is possible to detect stress-induced abnormalities of myocardial perfusion with Tc-99m-hexamibi similar to Tl-201 imaging.

Medullary thyroid carcinoma: localization of a mediastinal metastasis with I-131 MIBG

An I-131 metaiodobenzylguanidine (MIBG) scan was performed in a patient with a familial history of multiple endocrine neoplasia (MEN) type 2 and recurrent medullary thyroid carcinoma (MTC). The scan revealed a mediastinal metastasis from her MTC and there was also an imaging pattern of bilateral adreno-medullary hyperplasia. Although the literature indicates that I-131-MIBG scanning is not sufficiently sensitive for the detection of MTC, this procedure has proven to be of value in the management of chosen patients with MEN-associated MTC.