Intrasplenic masses of "preserved" functioning splenic tissue in sickle cell disease: correlation of imaging findings (CT, ultrasound, MRI, and nuclear scintigraphy)

PURPOSE: We studied six patients with sickle cell disease (SSD), five homozygous for sickle cell anemia and one with sickle beta-thalassemia, in whom rounded intrasplenic masses proved to be preserved functioning splenic tissue. MATERIALS AND METHODS: Available images including computed tomography, ultrasonography, bone scans (Tc-99m MDP), liver spleen scans (Tc-99m sulfur colloid), and MRI were evaluated. RESULTS: The masses were low density on CT (in an otherwise calcified spleen), hypoechoic relative to the echogenic spleen on US, and had the imaging characteristics of normal spleen on MRI. They failed to accumulate Tc-99m MDP but did demonstrate uptake of Tc-99m sulfur colloid. CONCLUSION: In a patient with SSD and intrasplenic masses, proper correlation of multiple imaging modalities will establish the diagnosis of functioning splenic tissue and avoid mistaken diagnosis of splenic abscess or infarction.     

99mTc-labeled solid-phase meal: a quantitative clinical measurement of human gastric emptying

A solid-phase meal labeled with 99mTc-sulfur colloid provides an improved clinical test for the quantitative evaluation of human gastric emptying. We studied 12 healthy male controls and five male patients with known gastric stasis secondary to a vagotomy and drainage procedure. All subjects were fasted for 8 hours before the study, and each consumed an unbuttered biscuit and a poached egg white containing 1 mCi of 99mTc-sulfur colloid. For 2 hours, 60-second counts were measured every 10 minutes by a Pho Gamma III scintillation camera. The t1/2 for control subjects was 60 minutes, at which time patients with gastric stasis had retained 98% of the test meal. At 120 minutes, control subjects and patients with gastric stasis had 4.7% and 89%, respectively, of the meal remaining in the stomach. The solid-phase test meal labeled with 99mTc-sulfur colloid is easy to perform and can be used clinically to quantitatively measure gastric emptying in humans. This test can discriminate between control subjects and patients with known gastric stasis.     

Rectal methohexital for sedation of children during imaging procedures

OBJECTIVE: Hypereosinophilic syndrome (eosinophilia without demonstrable cause) commonly involves eosinophilic infiltration of the liver and spleen, but few reports have described the imaging findings. Accordingly, we reviewed the imaging findings in five patients with this syndrome in whom the liver was involved. MATERIALS AND METHODS: Five patients who had hypereosinophilic syndrome with hepatic involvement were included in the study. The diagnosis of hepatic involvement was based on pathologic proof in two patients and on imaging and laboratory findings in the other three. Histologic examination of the hepatic lesions showed extensive eosinophilic infiltration in two patients and centrilobular necrosis in one. All patients had chest radiography, barium studies of the gastrointestinal tract, abdominal CT, and sonography. Four patients had hepatosplenic scintigraphy. All patients were followed up for 4-24 months. RESULTS: All patients had mild to marked hepatomegaly with multiple focal lesions. Focal lesions were detected on sonograms in three patients, on CT scans in four, and on scintigrams in three. On sonograms, the lesions were usually small (less than 2 cm in diameter), sharply or poorly defined nodules with varied echogenicity scattered throughout the liver. The lesions were hypodense with poorly defined margins on CT scans and appeared as variably sized areas of decreased radionuclide uptake on scintigrams. For each patient, the number, size, and shape of the lesions varied considerably from one imaging study to another. On follow-up studies 2-6 months after treatment, the appearance of the liver was normal. Other radiologic findings included transient pulmonary infiltrates (two patients), mild cardiomegaly (one patient), and mild lymphadenopathy (three patients). CONCLUSION: Hypereosinophilic syndrome is a cause of focal hepatic lesions seen on sonograms, CT scans, or scintigrams. The lesions are characterized by the varied appearance on the different types of images and the disappearance of the lesions with treatment.     

Long-term effects of ventilation tubes for persistent otitis media with effusion in children

OBJECTIVE: To analyze the clinical and scintigraphic features in four postoperative patients with lower limb edema. DESIGN: Four case reports are presented, and causes of increased lymphatic flow are discussed. MATERIAL AND METHODS: Filtered 99mTc-sulfur colloid (0.1 mL; 20 MBq) was administered by subcutaneous injection into the second web space of each foot. Sequential local (inguinal) and whole-body imaging was performed periodically up to 24 hours after the injections. The patients were three women who were 40, 51, and 86 years of age and an 81-year-old man. RESULTS: Each patient had unilateral lower extremity swelling and had recently undergone an ipsilateral lower limb operation. One female patient had previously undergone proximal femoral vein ligation, and another female patient had venous insufficiency demonstrated by Doppler ultrasonography. The male patient had a history of severe arterial insufficiency, and the remaining female patient had no venous or arterial abnormalities. On lymphoscintigraphy, all patients showed increased lymphatic flow in the edematous lower limb. Only the male patient also demonstrated abnormal dermal backflow pattern. CONCLUSION: Increased lymphatic flow most likely is a normal response to lower limb edema in the presence of normal peripheral lymphatic structures. In the four described cases, a recent lower limb surgical procedure may have resulted in disturbance of normal proximal lymphatic channels. The role of sympathetic innervation of the peripheral lymphatic system is a potential factor determining lymphatic response to trauma or surgical intervention. Increased flow on lymphoscintigraphy may not necessarily represent normal flow, especially if other scintigraphic features of abnormal lymphatic function-such as dermal backflow pattern-are present.     

Organ distribution of canine leukocytes labeled with 99mTc-sulfur colloid

Previous reports have shown that scintigraphic localization of acute inflammation can be achieved using autologous leukocytes labeled in vitro with 99mTc-sulfur colloid (TcSC). The technique is limited, however, by a marked accumulation of radioactivity in the lungs and liver of normal animals. A modified procedure was developed using preparations of TcSC of small particle size to label blood leukocytes in vitro. Markedly decreased levels of lung and liver radioactivity and elevated levels of blood radioactivity were found after intravenous infusion of autologous canine leukocytes labeled by this method. These leukocytes could be used to image areas of acute inflammation resulting from induction of septic or sterile venous thrombi.     

Comparison of the sensitivity of early versus delayed imaging with Tc-99m HMPAO WBC in children with inflammatory bowel disease

The difference in sensitivity of early imaging at 30 minutes after injection of Tc-99m HMPAO WBC versus delayed imaging at 2 or 3 hours for depiction of active inflammation in children with inflammatory bowel disease was established. The charts of 220 children who had early (30-minute) and delayed (2 or 3 hours) imaging performed for evaluation of inflammatory bowel disease were reviewed. There were 107 boys and 113 girls (average age, 12 years; median, 13 years). The bowel was divided into eight segments (with the total for all patients being 3,520) graded on a scale of 0 to 6 (with reference points in the iliac crest and liver). Any grade > or = 1 was abnormal. The uptake in each segment was summed. One hundred and twenty-two studies were abnormal (55%). The average uptake in the early images was 5.1 +/- 0.41 and that in the late images was 9.3 +/- 0.64. The Friedman nonparametric test of comparison of rank was significant at the 0.001 level. One hundred and five patients had abnormal studies at 30 minutes (88%). An additional 12% of patients had abnormal studies only on the late images. There were 245 abnormal segments at 30 minutes and 413 abnormal segments at 2 or 3 hours. When the uptake was analyzed segment by segment, 62 patients (52%) had abnormal segments at 30 minutes but also had additional abnormal segments at 3 hours. Sensitivity of Tc-99m HMPAO WBC imaging was significantly improved when late imaging was performed.     

The importance of adequate exercise in the detection of coronary heart disease by radionuclide ventriculography

Rest and exercise radionuclide ventriculograms were obtained on 77 symptomatic patients without prior documented coronary artery disease (CAD). Coronary artery disease was present by angiograms in 48. Radionuclide ventriculography (RNV) was abnormal in 41 patients (overall sensitivity 85%). In 29 patients with normal coronary arteries, RNV was normal in 24 (specificity 83%). To determine if the exercise level affects sensitivity, the studies were graded for adequacy of exercise. It was considered adequate if patients developed (a) chest pain, or (b) ST segment depression of at least 1 mm, or (c) if they achieved a pressure rate produce greater than 250. Among the 48 patients with coronary artery disease, 35 achieved adequate exercise. Thirty-three had an abnormal RNV (sensitivity 94%). In 13 patients who failed to achieve adequate exercise, RNV was abnormal in eight (sensitivity of only 62%). Some patients with coronary artery disease may have a normal ventricular response at inadequate levels of stress.     

Gastric emptying as an etiopathogenic factor in gastroesophageal reflux disease

The aim of this study is to evaluate gastric emptying change in patients with gastroesophageal reflux (GER). To this purpose, 36 patients with GER diagnosis and 18 control subjects have been studied. GER diagnosis was achieved by means of endoscopy, biopsy and 24 h continuous pH monitoring. Gastric emptying studies were performed on a two day basis, similar labelling meals were provided to patients and control subjects. Those consisted in a one-egg omelette, chicken (110 gr) and orange juice (200 ml). On first day liquid phase was labelled with 99mTc-diethylenetriamine pentaacetic acid (99mTc-DTPA), and on second day, the solid phase was labelled with 99mTc-sulfur colloid in the omelette (Labelling efficiency was 85.3 +/- 3.2%). The studies were carried out by imaging static anterior and posterior views every 20 minutes for a total of 180 minutes. Images were quantified obtaining solid and liquid gastric emptying curves. No statistical significative difference between patients and control subjects gastric emptying results were found. We can conclude that gastric emptying is not a main factor in the pathogenesis of gastroesophageal reflux.     

Management of specific medical conditions in the perioperative period

BACKGROUND: Reversal of ischemia after myocardial infarction by revascularization is worthwhile only if viability exists in a sufficiently large portion of the left ventricle. METHODS AND RESULTS: To determine myocardial hypoperfusion reversibility and its influence on segmental and global function, we studied 50 patients after myocardial infarction. Three technetium 99m-tetrofosmin scintigraphies were performed: 1 at rest, 1 after 0.6 mg sublingual nitroglycerin (NTG), and 1 after injection at peak stress. First-pass multigated radionuclide angiography was obtained at rest and after NTG. Each patient also underwent a stress redistribution-reinjection thallium-201 scintigraphy. During stress 99mTc-tetrofosmin, 104 segments had normal uptake, 51 showed moderately reduced uptake, and 186 had severely reduced uptake. Of these 186 segments, 33 (18%) improved at rest, and 41 (22%) improved only after NTG. Fifty-nine (79%) of these segments with improved uptake were also found to have reversible defects on 201TI imaging. In the 26 patients with ventricular dysfunction, a 73% agreement was found between the functional and 99mTc-tetrofosmin uptake post-NTG improvement, whereas a 69% agreement was found with thallium reinjection. No significant differences were seen between 99mTc-tetrofosmin and 201T1 imaging. CONCLUSION: Nitroglycerin administration during 99mTc-tetrofosmin scintigraphy improves the detection of myocardium with reversible hypoperfusion in patients with a previous myocardial infarction.     

Hepatolienal syndrome in patients with chronic lymphoid leukemia and liver cirrhosis: similarities and differences of macrophagal function

Macrophagal function of the liver and spleen was studied using 99mTc dynamic scintigraphy in 31 patients with chronic lymphoid leukemia (CLL) and 11 patients with hepatic cirrhosis (HC). Total accumulation of the radionuclide in the above patients took place with more active participation of the spleen and less active--of the liver. Macrophagal function of the spleen and the liver was activated in CLL patients, whereas hepatic cirrhosis was accompanied by enhanced splenic function and diminished capacity of the liver for phagocytosis. Mechanisms of such phenomena are discussed.     

Technetium 99m sulfur colloid scintigraphy to evaluate reticuloendothelial system function in dogs with portasystemic shunts

In a retrospective study, technetium 99m sulfur colloid scintigraphy was used to evaluate reticuloendothelial system function in 61 dogs with single congenital and 40 dogs with multiple acquired portasystemic shunts. Whole body reticuloendothelial function was measured by calculating the plasma clearance rate constant from a dynamic study of liver uptake of 99mTc sulfur colloid. Relative liver, spleen, and lung uptake, and a ratio of hepatic:extrahepatic uptake were measured on static equilibrium images. Results were compared with those of a group of 26 normal dogs. Compared with values for the group of normal dogs, the plasma clearance rate constant, relative liver uptake, and hepatic:extrahepatic uptake ratio were significantly decreased, and relative spleen and lung uptake were significantly increased in dogs with portasystemic shunts (P < .0001). The only significant difference between dogs with single congenital versus multiple acquired shunts was that the relative splenic uptake was higher in the former group (P < .0002). Based on these results, we concluded that dogs with portasystemic shunts have significantly impaired reticuloendothelial function. The primary cause of this dysfunction is likely a reduction in effective liver blood flow. Increases in spleen and lung reticuloendothelial activity did occur, but only partially compensated for the reduction of liver reticuloendothelial activity. Possible mechanisms for the increased spleen and lung uptake are discussed.     

Misperfusion of the liver during hepatic artery infusion chemotherapy: value of preoperative angiography and postoperative pump scintigraphy

OBJECTIVE: One purpose of this study was to determine if patients who have anatomic variations in their hepatic arteries are at increased risk for complications associated with the use of intrahepatic arterial infusion pumps. We also tried to determine the value of perfusion studies obtained with 99mTc-microspheres or 99mTc-macroaggregated albumin in detecting postoperative hepatic or visceral misperfusion and in predicting complications in patients with anatomic variants despite pre- or intraoperative attempts to correct the arterial abnormality. SUBJECTS AND METHODS: We prospectively compared findings on scintigrams obtained after delivering the radionuclide through intrahepatic arterial infusion pumps with anatomic variations in hepatic arteries seen on celiac and superior mesenteric hepatic arteriograms obtained before placement of the pump in 49 consecutive patients with colon carcinoma metastatic to the liver. RESULTS: Despite pre- or intraoperative attempts to correct arterial abnormalities to ensure optimal perfusion of the liver in 24 patients with hepatic arterial anomalies seen on preoperative arteriograms, only two patients had normal findings on postoperative perfusion studies performed with 99mTc-microspheres and/or 99mTc-macroaggregated albumin. Abnormalities included perfusion of extrahepatic organs, including the spleen in 12 patients, stomach in seven, bowel in four, and pancreas in three. Eight patients had no perfusion of the left lobe of the liver, and three had no perfusion of the right lobe. Two patients had minimal or no perfusion of both lobes. In 23 of 25 patients with no demonstrable variations in vascular anatomy on preoperative celiac and superior mesenteric arteriograms, findings on hepatic pump scintigrams were normal. Of the 24 patients with abnormal scintigraphic findings, 20 had subsequent clinical complications. However, only two of the 25 patients with normal scintigraphic findings had clinical complications. CONCLUSION: Our results indicate that patients with anatomic variations in the hepatic arterial system are at high risk for misperfusion during chemotherapy despite pre- or intraoperative efforts to alter the perfusion for chemotherapeutic agents delivered by intrahepatic arterial infusion pumps. Misperfusion can be detected by using pump scintigraphy, and therefore patients should be closely monitored with 99mTc-macroaggregated albumin perfusion studies to ensure successful delivery of the chemotherapeutic agents and to avoid serious clinical complications caused by inadvertent perfusion of other organs.     

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

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

Splenunculectomy in recurrent thrombocytopenia

A 13-year-old boy developed thrombocytopenic purpura in 1953 which improved during 4 weeks of cortisone therapy. Following 13 years of intermittent symptoms the platelet count was found to be 8,000/mul. After splenectomy the patient was asymptomatic for 8 years, but had a recurrence of symptoms and thrombocytopenia in 1974. An initial spleen scan with 99Tcm sulfur colloid was negative; but when repeated with a gamma-camera and shielded liver, a splenunculus was demonstrated. After splenunculectomy a rapid remission occurred, and the patient has been well for 13 months.     

The abnormal hepatic scan of chronic liver disease: its relationship to hepatic hemodynamics and colloid extraction

To help explain the characteristic hepatic scan pattern of chronic liver disease, the degree of scan abnormality (scan score, SS) after administration of technetium-99m sulfur colloid (Tc) was compared with data obtained at hepatic vein catheterization in 28 patients. Although SS showed a correlation with wedged hepatic vein pressure (r = +0.491), the scan abnormality was not directly due to portal hypertension because it remained unchanged when the latter was relieved by portacaval shunt. Also, the scan abnormality was found to be unrelated to a low hepatic blood flow. Scan abnormality was not attributable primarily to hyperactivity of the reticuloendothelial (RE) cells of the spleen and bone marrow since fractional clearance (K) of Tc from the blood was decreased rather than increased in patients with abnormal scans. SS was inversely correlated with K or Tc (r = -0.575) and with hepatic extraction efficiency for Tc (r = -0.673), showing that the basic abnormality was poor extraction of the colloid by the RE cells of the liver with a resultant increase in the amount available for extrahepatic localization. Indirect evidence suggests that this poor extraction of colloid is due to intrahepatic shunts bypassing hepatic RE cells.     

Technetium-99m tetrofosmin imaging in thyroid diseases: comparison with Tc-99m-pertechnetate, thallium-201 and Tc-99m-methoxyisobutylisonitrile scans

Technetium-99m tetrofosmin is a lipophilic phosphine used for myocardial perfusion imaging. Biodistribution studies have shown significant thyroid uptake of tetrofosmin and preliminary reports have suggested that tetrofosmin imaging may be of value in patients with thyroid cancer. In this study, tetrofosmin whole-body scintigraphy was performed in 35 patients with evidence of thyroid diseases. All patients underwent laboratory evaluation of thyroid function as well as 99mTc pertechnetate scan, thallium-201 (n=16) 99mTc-methoxyisobutylisonitrile (MIBI) (n=19) whole-body studies. Thyroid images were semi-quantitatively analysed by a 4-point score: 0=no significant uptake; 1=uptake increased as compared to background activity, but inferior to normal thyroid tissue; 2=uptake equal to normal thyroid tissue; 3=uptake superior to normal thyroid tissue. Pathology examinations were obtained. A total of 41 thyroid nodules were detected, of which 15 were goitre nodules, 13 adenomas and 13 malignant lesions. In goitre nodules, concordant results of tetrofosmin and pertechnetate uptake (score 1 or 0) were observed in the majority of lesions (87%). In function adenomas (n=10), both tetrofosmin uptake and pertechnetate uptake were score 3. In non-function adenomas (n=3), tetrofosmin uptake was score 3, while pertechnetate uptake was score 0. In six malignant lesions, tetrofosmin uptake was score 3, while pertechnetate uptake was score 0; in the other seven lesions, where a prevalence of goitre abnormalities was observed, results of tetrofosmin and pertechnetate uptake were similar (score 0 or 1). In seven (70%) of the ten patients with malignant nodules, whole-body tetrofosmin images showed increased abnormal uptake in a total of 28 extra-thyroid tumour sites, as subsequently confirmed by other techniques. When tetrofosmin images were compared to 201Tl and 99mTc-MIBI scans, concordant results were observed in all cases. In conclusion, tetrofosmin imaging may be particularly useful to characterize and stage patients with malignant thyroid nodules; it shows similar results to thallium but provides better image quality. Comparable findings were observed between tetrofosmin and MIBI studies. Thus, tetrofosmin may be an alternative to thallium and MIBI in the aforementioned patients.     

Sidestream tobacco smoke exposure acutely alters human nasal mucociliary clearance

Nasal mucociliary clearance (NMC) is a biomarker of nasal mucosal function. Tobacco smokers have been shown to have abnormal NMC, but the acute effect of environmental tobacco smoke (ETS) on nonsmokers is unknown. This study evaluated acute tobacco smoke-induced alterations in NMC in 12 healthy adults. Subjects were studied on 2 days, separated by at least 1 week. Subjects underwent a 60-min controlled exposure at rest to air or sidestream tobacco smoke (SS) (15 ppm CO) in a controlled environmental chamber. One hour after the exposure, 99mTc-sulfur colloid was aerosolized throughout the nasal passage and counts were measured with a scintillation detector. Six out of 12 subjects showed more rapid clearance after smoke exposure than after air exposure, and 3/12 had rapid clearance on both days. However, substantial decreases in clearance occurred in 3/12 subjects, all of whom had a history of ETS rhinitis. In two subjects, more than 90% of the tracer remained 1 hr after tracer administration (2 hr after smoke exposure). Understanding the basis for biologic variability in the acute effect of tobacco smoke on NMC may advance our understanding of pathogenesis of chronic effects of ETS.     

Technetium-99m stannous pyrophosphate scintigrams in normal subjects, patients with exercise-induced ischemia and patients with a calcified valve

Although technetium-99m stannous (99mTc[Sn]) pyrophosphate has been shown to be a specific and sensitive index of myocardial infarction, abnormal images have been reported in patients with unstable angina or ventricular aneurysm. Sixty-one subjects--33 patients subjected to maximal treadmill stress testing, 23 normal subjects and 5 patients with a calcified aortic or mitral valve--underwent imaging with 99mTc(Sn) pyrophosphate to determine whether abnormal images are associated with (1) exercise-induced ischemia, (2) delayed clearance of tracer from the blood pool, or (3) calcified intracardiac structures. Myocardial injury was excluded on the basis of normal MB creatine kinase (CK) values in all patients with stress testing. All eight patients with an abnormal exercise stress test had normal images. Four of 25 patients with a normal exercise stress test had diffusely abnormal images. In some normal subjects diffusely abnormal images were present 60 minutes after injection of the tracer, but became normal 90 to 120 minutes after injection. Variations in clearance of tracer from the blood pool were noted in this group. Patients with a calcified aortic or mitral valve had normal images. We conclude that (1) exercise-induced ischemia is not associated with abnormal 99mTC(SN) pyrophosphate images; (2) images are not necessarily abnormal in patients with a calcified valve; and (3) delayed removal of tracer from the cardiac blood pool may result in diffusely abnormal images even in normal subjects; in these cases, repeat images should be obtained at least 2 hours after injection of the tracer to avoid false abnormal images.     

Imaging experimental infective endocarditis with indium-111-labeled blood cellular components

The capability of radionuclide imaging to detect experimental aortic valve infective endocarditis was assessed with indium-111 (111In)-labeled blood cells. Sequential cardiac imaging and tissue distribution studies were obtained in 17 rabbits with infective endocarditis after administration of 111In-platelets and in five after 111In-polymorphonuclear leukocytes. Forty-eight to 72 hours after platelet administration, in vivo imaging demonstrated abnormal 111In uptake in all animals in the region of the aortic valve in an anatomically distinct pattern. Images of the excised heart showed discrete cardiac uptake conforming to the in vivo image and gross pathological examination. 111In platelet uptake in vegetations from the 17 animals averaged 240 +/- 41 times greater than that in normal myocardium and 99 +/- 15 times greater uptake in blood. In contrast, 111In-leukocyte cardiac imaging showed no abnormal aortic valve uptake 24 hours after tracer administration and the lesion myocardium activity ratio was only 5 +/- 2 (3 +/- 1 for lesion/blood activity). Four normal rabbits demonstrated neither positive 111In platelet scintigraphs nor abnormal cardiac tissue uptake. Likewise, noncellular 111In was not concentrated to any significant extent in three animals with infective endocarditis. This study demonstrates that 111In platelet, but not leukocyte cardiac imaging, is a sensitive technique for detecting experimental infective endocarditis. The imaging data conform to the cellular pathology of the infective endocarditis vegetation.     

Preoperative parathyroid gland localization with technetium-99m sestamibi in secondary hyperparathyroidism

Technetium-99m sestamibi scintigraphy has become a valuable tool in locating parathyroid glands in patients with primary hyperparathyroidism. The aim of this study was to evaluate its usefulness in secondary hyperparathyroidism. Twenty patients were injected intravenously with 740 MBq of 99mTc-sestamibi and images were obtained at 15 min and 2 h post injection. All patients underwent parathyroid ultrasonography (US) as well as bilateral surgical neck exploration and 64 parathyroid glands were removed. US revealed at least one enlarged gland in 15/20 patients (75%), while 99mTc-sestamibi scintigraphy showed focal areas of increased uptake in at least one gland in 17/20 patients (85%). When imaging results for all glands were evaluated according to surgical results, sensitivity was 54% for parathyroid scintigraphy and 41% for US, and specificity was 89% for both imaging techniques. There was a discrepancy between the two imaging modalities in 28 glands (35%). The mean surgical weight of US-positive glands (1492+/-1436 mg) was significantly higher than that of US-negative glands (775+/-703 mg) (P<0.05). However, there were no significant differences in weight between sestamibi-positive and sestamibi-negative glands. When only sestamibi-positive glands were considered, a positive correlation between uptake and weight was found (r=0.4, P<0.05). In conclusion, parathyroid US and 99mTc-sestamibi scintigraphy are complementary imaging techniques in the preoperative localization of abnormal parathyroid glands in patients with secondary hyperparathyroidism. The limited sensitivity of the techniques means that patients will still require bilateral neck exploration; therefore routine preoperative parathyroid scanning in renal patients is not justified.