technetium-tc-99m-exametazime and Appendicitis

Several strategies have been employed to improve the accuracy of the diagnosis of appendicitis and to reduce the associated perforation rate. Because clinical algorithms have been disappointing, many physicians resort to radiological modalities. Plain abdominal x-rays are nonspecific, barium enema examination has relatively low accuracy, scintigraphy scans require considerable time and are difficult to interpret, and magnetic resonance imaging is relatively unstudied. The most promising modalities are graded compression sonography and computed tomography. In expert hands, these techniques can achieve a high degree of accuracy. Nevertheless, most published studies have been marred by methodological difficulties. Moreover, ultrasound is more useful in detecting than in ruling out appendicitis. The radiological criteria for acute appendicitis, the accuracy of various imaging modalities and the limitations of the available research are described.

Topics: Acute Disease; Appendicitis; Barium Sulfate; Diagnosis, Differential; Enema; Humans; Magnetic Resonance Imaging; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, X-Ray Computed; Ultrasonography, Doppler, Color

Acute appendicitis is a clinically challenging surgical disease particularly difficult to diagnosis in women and children. An atypical presentation of acute appendicitis is a major factor leading to delay in diagnosis and unnecessary surgery. Delay in diagnosis is associated with morbidity from perforation, abscess and prolonged hospitalization. The routine use of adjunctive imaging studies has not improved the diagnostic accuracy for acute appendicitis nor has impacted clinical outcome. 99mTc HMPAO-labeled leukocyte imaging is one diagnostic imaging test that has the potential of altering the clinical management of acute appendicitis. 99mTc HMPAO-labeled leukocyte imaging is highly sensitive for detecting even small inflammatory processes in the abdomen because of high target to background and early rapid uptake at sites of inflammation. We studied the use of 99mTc HMPAO-labeled leukocytes for diagnosis and management of suspected acute appendicitis in 124 patients with an atypical clinical presentation. Emergent imaging was performed immediately following injection of labeled leukocytes and continued until positive or through 2 hours if negative. The scan correctly and rapidly detected acute appendicitis in 50 of 51 patients with surgical confirmation for a sensitivity of 98%. The specificity was 82% leading to an overall accuracy of 90%. The high negative predicted value of 98% allowed early discharge from the emergency department and avoided costly observation in the hospital and potentially unnecessary surgery in these patients with negative scans. The negative exploratory laparotomy rate was 4% in this patient population compared to 9% in a similar population of patients who were not scanned. These data have been confirmed now in over 600 patients scanned in our department. The main drawbacks of 99mTc HMPAO-labeled leukocyte imaging are the requirement of blood handling and a delay in diagnosis because of the 2-hours preparation time prior to imaging. There are new radiopharmaceuticals on the horizon which have the potential of replacing 99mTc HMPAO-labeled leukocyte imaging and offer advantages of a shorter preparation time and no blood handling. These include 99mTc labeled monoclonal antibodies and chemotactic peptides. The 99mTc anti-SSEA-1 IgM antibody (LeuTech) is currently under investigation for use in acute appendicitis. In summary, nuclear medicine can play a key role in the diagnosis of acute appendicitis in patients with an atypical prese

Topics: Acute Disease; Antibodies, Monoclonal; Appendicitis; Female; Humans; Isotope Labeling; Leukocytes; Male; Peptides; Radionuclide Imaging; Sensitivity and Specificity; Technetium Tc 99m Exametazime

Various imaging studies can be performed in the evaluation of patients with a clinical presentation equivocal for acute appendicitis. One of these studies is technetium-99m hexamethylpropylene amine oxime (HMPAO) labelled white blood cell (WBC) scintigraphy. The aim of this study was to evaluate the accuracy and clinical value of 99mTc-HMPAO WBC scintigraphy in the aforementioned group of patients. Forty-one patients who had acute right lower quadrant abdominal pain with a clinical presentation equivocal for acute appendicitis were included in the study. The anterior abdomen and pelvis were imaged up to 4 h after the injection of 125-300 MBq 99mTc-HMPAO WBCs and the results were immediately reported to the surgeon before a decision was taken on whether to perform laparotomy. Diagnostic accuracy was established by the intra-operative findings and the histopathology in operated patients. In non-operated patients, absence of abdominal symptoms 1 month after scintigraphy and/or identification of another cause of abdominal pain was used to rule out acute appendicitis. There were 16 patients with positive scintigraphy and 81% of these patients were positive within 2 h post injection. There were no false-positive or false-negative results. We operated on 17 (41.4%) patients, and only one patient (5.9%) underwent unnecessary laparotomy. We conclude that 99mTc-HMPAO WBC scintigraphy is a rapid, highly accurate method for the exclusion of acute appendicitis and that its use can lower the unnecessarily high laparotomy rate in patients with an equivocal clinical presentation.

Topics: Acute Disease; Adolescent; Adult; Appendicitis; Child; Female; Humans; Leukocytes; Male; Prospective Studies; Radionuclide Imaging; Radiopharmaceuticals; Technetium Tc 99m Exametazime

The authors' goal was to evaluate the accuracy of Technetium 99m-HMPAO-labeled leukocyte imaging for screening patients with atypically presenting appendicitis and to determine how availability of this test affected practice patterns of surgeons at the authors' medical center.. Appendicitis can be difficult to diagnose and in equivocal cases usually requires inpatient observation. The delay may increase morbidity and costs. A test that rules out acute appendicitis could be cost effective if it allowed early discharge from the emergency department. Previously, there have been no simple, rapid, accurate noninvasive methods for improving diagnostic accuracy in patients with equivocal presentations of appendicitis.. Patients referred to rule out appendicitis were analyzed. Patients were imaged up to 3 hours after injection of 10-mCi 99mTc-HMPAO-labeled autologous leukocytes (Tc-WBC), and when the scans became positive, imaging was terminated and the requesting physician notified of the results. Diagnostic accuracy was established by surgical and histopathologic findings or by absence of symptoms after 1 month clinical follow-up. The source of referral, hospital length of stay, disposition of patients, and ancillary tests (ultrasound, computed tomographic scan, and barium enema) were analyzed.. One hundred twenty-four patients were studied from November 1991 through December 1995. Fifty-eight percent of positive scans showed uptake within 1 hour of injection and 73% by 2 hours. The Tc-WBC scan correctly identified an inflammatory source of abdominal pain in 65 of 66 cases (sensitivity = 98%) and was correctly negative in 55 of 58 cases (specificity = 95%). The scan correctly diagnosed appendicitis in 50 of 51 cases (sensitivity = 98%) and correctly excluded appendicitis in 62 of 73 cases (specificity = 85%). Outpatient referrals increased from 38% to 87%. In those patients with negativescans, inpatient observation, number of adjunctive tests, and length of stay decreased significantly.. The high sensitivity and negative predictive value of Tc-WBC imaging may permit patients to be screened and discharged from the emergency department. Focally positive scans often indicate disease requiring operation but not in all cases. The Tc-WBC imaging reduced the negative laparotomy rate to 3.9% while reducing admission rates and hospital length of stay.

Topics: Acute Disease; Adult; Appendicitis; Emergencies; Female; Follow-Up Studies; Humans; Leukocytes; Male; Organotechnetium Compounds; Oximes; Predictive Value of Tests; Prospective Studies; Radionuclide Imaging; Referral and Consultation; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Time Factors

A prompt and accurate diagnosis of appendicitis in pregnant patients is important in avoiding premature labor and fetal loss. Computed tomography (CT) scans are accurate, but fetal radiation exposure is high. Ultrasound avoids radiation exposure, but is less accurate as the uterus enlarges. A third option involves the use of technetium-99 tagged white blood cell scans (TWBCS), which have less than 5 per cent of the fetal radiation exposure of CT scans. However, in pregnancy, the value of TWBCS has not been studied. Therefore, a retrospective review of all patients who were pregnant and underwent a nuclear medicine study as part of their evaluation was performed. Thirteen patients were identified from 1999 through 2005. Before receiving a TWBCS, each patient had an indeterminate physical examination and an ultrasound or CT. Patients with negative TWBCS were admitted and observed clinically. There was no relationship between the results of TWBCS and the presence of appendicitis (P = 0.538). The sensitivity of the TWBCS was 50 per cent, whereas the specificity was 73 per cent. TWBCS had a false-positive rate of 27 per cent and a false-negative rate of 50 per cent, and its positive predictive value was 25 per cent. The data suggest that TWBCS in pregnancy is not reliable in evaluating for appendicitis.

Topics: Adolescent; Adult; Appendicitis; False Negative Reactions; False Positive Reactions; Female; Humans; Leukocytes; Physical Examination; Predictive Value of Tests; Pregnancy; Pregnancy Complications; Radionuclide Imaging; Radiopharmaceuticals; Reproducibility of Results; Retrospective Studies; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, X-Ray Computed; Ultrasonography

Diagnosing acute appendicitis in children with equivocal signs and symptoms may be difficult. The usual approach is hospital observation and frequent re-examination. However, many surgeons are reluctant to delay surgery because of the risk of perforation and a negative laparotomy.. To assess and compare the value of the technetium-99m hexamethylpropylene amine oxime ((99m)Tc-HMPAO)-labelled white-blood-cell (WBC) abdomen scan in the diagnosis of acute appendicitis in children with atypical clinical presentation.. Fifty children with acute right lower quadrant abdominal pain and possible acute appendicitis, but atypical findings were included. After IV injection of (99m)Tc-HMPAO-labelled WBCs, serial anterior abdomen scans were obtained using a gamma camera.. Thirty-three children underwent surgery, while 17 children were managed conservatively and were followed up for at least 1 month. Four children had false-positive results and one child had a false-negative scan result. The overall sensitivity, specificity, accuracy, positive predictive value and negative predictive value of the scan to diagnose acute appendicitis in children with atypical findings was 96.7, 80.0, 90.0, 87.8 and 94.1%, respectively.. The (99m)Tc-HMPAO WBC abdomen scan is a potential tool for diagnosing acute appendicitis in children with atypical clinical findings. The high sensitivity and negative predictive value allows early discharge from the emergency department to avoid costly observation in hospital and potentially unnecessary surgery in those patients with negative scans.

Topics: Acute Disease; Adolescent; Appendicitis; Child; Diagnosis, Differential; False Negative Reactions; False Positive Reactions; Female; Gamma Cameras; Humans; Leukocytes; Male; Radionuclide Imaging; Radiopharmaceuticals; Sensitivity and Specificity; Technetium Tc 99m Exametazime

Even with careful observation, the overall false-positive rate of laparotomy remains 10-15% when acute appendicitis was suspected. Therefore, the clinical efficacy of Tc-99m HMPAO labeled leukocyte (TC-WBC) scan for the diagnosis of acute appendicitis in patients presenting with atypical clinical findings is assessed.. Eighty patients presenting with acute abdominal pain and possible acute appendicitis but atypical findings were included in this study. After intravenous injection of TC-WBC, serial anterior abdominal/pelvic images at 30, 60, 120 and 240 min with 800 k counts were obtained with a gamma camera. Any abnormal localization of radioactivity in the right lower quadrant of the abdomen, equal to or greater than bone marrow activity, was considered as a positive scan.. 36 out of 49 patients showing positive TC-WBC scans received appendectomy. They all proved to have positive pathological findings. Five positive TC-WBC were not related to acute appendicitis, because of other pathological lesions. Eight patients were not operated and clinical follow-up after one month revealed no acute abdominal condition. Three of 31 patients with negative TC-WBC scans received appendectomy. They also presented positive pathological findings. The remaining 28 patients did not receive operations and revealed no evidence of appendicitis after at least one month of follow-up. The overall sensitivity, specificity, accuracy, positive and negative predictive values for TC-WBC scan to diagnose acute appendicitis were 92, 78, 86, 82, and 90%, respectively.. TC-WBC scan provides a rapid and highly accurate method for the diagnosis of acute appendicitis in patients with equivocal clinical examination. It proved useful in reducing the false-positive rate of laparotomy and shortens the time necessary for clinical observation.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Appendectomy; Appendicitis; Child; False Negative Reactions; False Positive Reactions; Female; Humans; Leukocytes; Male; Middle Aged; Radionuclide Imaging; Radiopharmaceuticals; Reproducibility of Results; Technetium Tc 99m Exametazime

We evaluated Tc-99m-labeled anti-CD15 immunoglobulin M monoclonal antibody (LeuTech) for scintigraphic detection of acute appendicitis in patients with an equivocal clinical presentation. LeuTech avidly binds to circulating and sequestered human polymorphonuclear neutrophils in vivo eliminating the need for in vitro cell labeling and the risks of blood handling. We studied 99 patients to evaluate the safety and efficacy of LeuTech imaging. Serial dynamic and static planar images were acquired for up to 3 hours after the intravenous administration of 10 to 20 mCi of Tc-99m LeuTech. Scans were read as positive or negative for acute appendicitis or other intra-abdominal infection. The institutional diagnosis was established by surgery and histopathology of the appendix, results of other diagnostic studies, or 2-week clinical follow-up. Scans were positive for appendicitis in 39 of 40 patients with appendicitis at surgery (sensitivity 98%) and negative for appendicitis in 49 of 58 patients without appendicitis (specificity 84%). One was lost to follow-up. Accuracy, positive predictive value, and negative predictive value were 90, 81, and 98 per cent respectively. In patients with appendicitis and positive scans more than 50 per cent of the images were positive at 4 minutes, and all were positive by 1 hour. Mean time of first positive image was 15 minutes. There were no serious adverse reactions. We conclude that LeuTech imaging is a highly sensitive test for detection of appendicitis in equivocal cases. There are advantages of this agent over the other currently used radiotracers in terms of convenience and time to diagnosis particularly the rapidity with which acute appendicitis will be seen on the images.

Topics: Abdomen; Abdominal Pain; Acute Disease; Antibodies, Monoclonal; Appendectomy; Appendicitis; Follow-Up Studies; Humans; Immunoglobulin M; Injections, Intravenous; Lewis X Antigen; Neutrophils; Predictive Value of Tests; Radioimmunodetection; Radiopharmaceuticals; Safety; Sensitivity and Specificity; Technetium Tc 99m Exametazime

We attempted to label leukocytes with stabilized Tc-99m D,L-HMPAO by methylene blue and sodium phosphate buffer (S-HMPAO).. The results were compared with unstabilized Tc-99m D,L-HMPAO (U-HMPAO). U-HMPAO was obtained by reconstituting a commercial vial of D,L-HMPAO. Stabilization of the kit was performed by the addition of methylene blue. The leukocytes were labeled using a modified published method. The test samples of S-HMPAO and U-HMPAO were prepared immediately, and stood for 0.5, 1, 2, 4, and 6 h, respectively, at room temperature before analysis.. In comparison with U-HMPAO: (1) the radiochemical purity of S-HMPAO was higher; (2) the labeling efficiencies of S-HMPAO labeled leukocytes were higher and consistent; (3) the viability of S-HMPAO labeled leukocytes was as high as the viability of U-HMPAO labeled leukocytes at any time; and (4) the percentages of disintegrated from S-HMPAO labeled leukocytes in plasma were lower.. S-HMPAO is more stable than U-HMPAO and can provide higher leukocyte labeling efficiency. S-HMPAO, therefore, has the potential to replace U-HMPAO as a leukocyte-labeling agent.

Topics: Appendicitis; Buffers; Cerebrovascular Circulation; Drug Stability; Humans; In Vitro Techniques; Leukocytes; Male; Methylene Blue; Middle Aged; Phosphates; Radionuclide Imaging; Radiopharmaceuticals; Technetium Tc 99m Exametazime

Forty-nine patients (age > 50 years) with an acute abdomen and suspected appendicitis, but with atypical findings, were included in the study. After the intravenous injection of 99Tcm-hexamethylpropylene amine oxime (99Tcm-HMPAO) labelled white blood cells (WBCs), serial anterior images of the abdomen and pelvis were obtained after 30, 60, 120 and 240 min. Any abnormal localization of WBC accumulation in the right lower quadrant of the abdomen equal to or greater than bone marrow activity was considered positive. Twenty-five patients had positive WBC scans, all of whom underwent laparotomy. Twenty-three of these patients were shown to have appendicitis; the other 2 did not. The other 24 patients had a negative WBC scan, 2 of whom underwent laparotomy and were shown to have appendicitis; the other 22 patients did not undergo surgery and showed no evidence of appendicitis during follow-up. The overall sensitivity, specificity, accuracy, positive and negative predictive values of WBC scans for diagnosing appendicitis were as follows: 92.0%, 91.7%, 91.8%, 92.0% and 91.7% respectively. In conclusion, 99Tcm-HMPAO-labelled WBC scans provide a rapid and highly accurate method for diagnosing appendicitis in older patients with equivocal clinical findings.

Topics: Abdomen, Acute; Abscess; Acute Disease; Aged; Appendicitis; False Negative Reactions; False Positive Reactions; Female; Humans; Injections, Intravenous; Leukocytes; Male; Middle Aged; Organotechnetium Compounds; Oximes; Predictive Value of Tests; Technetium Tc 99m Exametazime; Tissue Distribution; Tomography, Emission-Computed

We used a radiolabeled white blood cell (WBC) scan as an adjunct to diagnose appendicitis in 100 children with equivocal signs or symptoms of appendicitis. WBC separation and labeling took 2 hours. Patients were imaged up to 3 hours after injection of labeled Tc-WBC. Accuracy was established in all 100 children by histopathological findings, medical records and follow-up interviews. Scans were positive in 40 and negative in 60. Positive scans averaged 76 +/- 40 minutes after injection (mean +/- SD); negative scans required 150-180 minutes. Tc-WBC scan correctly identified appendicitis in 36 of 37 children (sensitivity, 97%) and correctly excluded appendicitis in 59 of 63 (specificity, 94%). The false negative scan occurred in a patient whose perforated appendix was discovered at operation 3 days following the scan. Accuracy of the examination was 95 per cent, with a positive predictive value of 90 per cent and a negative predictive value of 98 per cent. The negative laparotomy rate for the entire group was 4 per cent. Tc-WBC imaging is an accurate, noninvasive test for ruling out appendicitis in children with right lower quadrant abdominal pain and equivocal presentation, although positive scans require more clinical judgment. The high sensitivity and negative predictive value suggest its potential for screening and discharging children from the emergency department.

Topics: Abdominal Pain; Acute Disease; Adolescent; Appendicitis; Child; Child, Preschool; Diagnosis, Differential; Emergency Service, Hospital; False Negative Reactions; Female; Follow-Up Studies; Humans; Injections, Intravenous; Interviews as Topic; Intestinal Perforation; Laparotomy; Leukocytes; Male; Medical Records; Mesenteric Lymphadenitis; Patient Discharge; Predictive Value of Tests; Prospective Studies; Radionuclide Imaging; Radiopharmaceuticals; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Time Factors

Fifty female patients with acute abdomen and suspected appendicitis but atypical findings were included in this study. After intravenous injection of Tc-99m HMPAO-labeled WBCs, serial anterior abdominal/pelvic images at 30, 60, 120, and 240 minutes were obtained by a gamma camera. Any abnormal localization of WBC accumulation in the right lower quadrant of the abdomen with equal to or greater than bone marrow activity was considered as a positive scan. Thirty patients had positive WBC scans and underwent laparotomy, 28 had proven appendicitis, and 2 were not related to appendicitis. Twenty patients had negative WBC scans, 2 patients underwent laparotomy and were proved to have appendicitis. The remaining 18 patients did not undergo surgery and revealed no evidence of appendicitis after follow-up. The overall sensitivity, specificity, accuracy, and positive and negative predictive values for WBC scans to diagnose appendicitis is 93.3%, 90.0%, 92.0%, 93.3%, and 90.0%, respectively. In conclusion, Tc-99m HMPAO-labeled WBC imaging provides a rapid and highly accurate method for diagnosis of appendicitis in female patients with equivocal clinical examinations.

Topics: Adolescent; Adult; Aged; Appendicitis; Child; Child, Preschool; Cystitis; Diagnosis, Differential; Female; Humans; Leukocytes; Middle Aged; Organotechnetium Compounds; Oximes; Pelvic Inflammatory Disease; Radionuclide Imaging; Sensitivity and Specificity; Technetium Tc 99m Exametazime

To determine the accuracy and reliability of a labeled leukocyte imaging technique in the early diagnosis of pediatric appendicitis, we prospectively studied patients presenting to the pediatric emergency department with abdominal pain suggestive of appendicitis. Patients scheduled for urgent laparotomy were excluded, as were postmenarchal females. Blinded interpretations by two independent radiologists were compared with surgical findings, if managed operatively, or with discharge diagnoses and three week follow-up, if managed medically. Twenty-three children underwent technetium-99m hexamethylpropylene amine oxime (HMPAO) leukocyte scintigraphy. Seven had pathologically proven appendicitis, with false negative interpretations made in three and five cases by the two radiologists. Sixteen patients had prompt resolution of symptoms; however, scintigraphic abnormalities were identified in 10 and seven cases by the two radiologists. Resulting sensitivity, depending on the individual reader, ranged from 29 to 57%, with specificity 38 to 56%, positive predictive value 22 to 29%, negative predictive value 64 to 67%, and accuracy 43 to 48%. Interrater reliability for agreement on the scintigraphic diagnosis of appendicitis was poor (kappa = 0.38). Technetium-99m HMPAO leukocyte scintigraphy was neither accurate nor reliable as a diagnostic tool in a subgroup of pediatric patients with an initial clinical presentation equivocal for appendicitis. This finding contradicts previously published experience using similar scintigraphic techniques.

Topics: Abdominal Pain; Adolescent; Appendicitis; Child; Child, Preschool; Diagnosis, Differential; Female; Humans; Leukocytes; Male; Observer Variation; Organotechnetium Compounds; Oximes; Prospective Studies; Radiography; Radionuclide Imaging; Sensitivity and Specificity; Technetium Tc 99m Exametazime

Patients with acute lower abdominal pain remain a diagnostic challenge. Although acute appendicitis is the most common surgical disorder, its accurate and timely diagnosis can be difficult. Historically, females of childbearing age are the most difficult patient group in whom to make the diagnosis of acute appendicitis; they have reported negative laparotomy rates ranging from 30 to 50 percent. Tc-99 hexamethylpropyleneamineoxide (HMPAO) labeled leukocyte scan has previously been shown to be very accurate in the detection of acute appendicitis.. One year ago, a blinded study using Tc-99 HMPAO labeled leukocyte scan was reported for the detection of acute appendicitis. That study consisted of 27 patients who presented with abdominal pain. The present report is a follow-up study of 37 additional patients in whom the Tc-99 HMPAO leukocyte scan was used to diagnose or discount acute appendicitis.. Twenty-seven patients had histologically proved acute appendicitis. Twenty-three of these were correctly diagnosed using the leukocyte scan, for a sensitivity rate of 85 percent. The overall specificity rate was 93 percent, with an overall accuracy rate of 89 percent. Thirty-one of 64 patients were females of reproductive age and represented 56 percent of all patients in the study with appendicitis. In this group, the Tc-99 HMPAO leukocyte scan had a sensitivity rate of 87 percent, specificity rate of 92 percent, and an overall accuracy rate of 89 percent. The Tc-99 HMPAO leukocyte scan also proved to be valuable in the diagnosis of other intra-abdominal inflammatory conditions. Eight scans interpreted as negative for acute appendicitis were positive for other conditions, including five that were positive for diverticulitis, one for a tumor, one for a tubo-ovarian abscess, and one for a small intestinal infarction.. The Tc-99 HMPAO leukocyte scan is a highly accurate, diagnostic, and minimally invasive test of use in patients with abdominal pain of unclear cause, in which the differential diagnosis includes acute appendicitis. It is of particular value in females of childbearing age, in whom the cause of lower abdominal pain is unclear.

Topics: Abdominal Pain; Acute Disease; Adult; Appendicitis; Diagnosis, Differential; Diverticulitis; Female; Follow-Up Studies; Humans; Inflammation; Leukocytes; Male; Organotechnetium Compounds; Oximes; Prospective Studies; Radionuclide Imaging; Sensitivity and Specificity; Single-Blind Method; Technetium Tc 99m Exametazime; Ultrasonography

Scintigraphy with Tc-99m labeled antigranulocyte antibodies (BW 250/183 MoABs) was performed in 32 patients with suspected appendicitis. Abdominal imaging (planar/SPECT) was performed 2 hours after injection of the tracer. All patients also had surgery and a histologic examination of the resected tissue. Of the patients, 17 suffered from "acute appendicitis" and 12 had right positive scans (sensitivity = 70.6%). In 15 patients, acute appendicitis could have been ruled out, and in 11 of these cases the scan was true negative (specificity = 73.3%). The overall accuracy was 71.8% (23/32 cases). The use of Tc-99m antigranulocyte MoABs may overcome the problems associated with the Tc-99m HMPAO granulocyte and In-111 oxine approaches, which include nonspecific intestinal activity or the lack of timeliness. The use of Tc-99m labeled antigranulocyte antibodies is suitable as an emergency procedure and may play a role in the management of patients with suspected appendicitis.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Appendicitis; Child; Female; Granulocytes; Humans; Indium Radioisotopes; Leukocytes; Male; Middle Aged; Organometallic Compounds; Organotechnetium Compounds; Oximes; Oxyquinoline; Radioimmunodetection; Sensitivity and Specificity; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

The diagnosis of acute appendicitis can be difficult. Barium enemas, computed tomography (CT) scans, ultrasound examinations and Indium scans are used to aid in making the diagnosis with varying degrees of success. This blinded, prospective study reports the use of a Technetium 99-m Hexamethylpropyleneamineoxide (HMPAO) labelled white blood cell scan in 30 patients with suspected appendicitis. Autologous white blood counts from 25 cc of whole blood labelled with Tc-99 HMPAO were reinjected into patients. Abdominal imaging was performed at a half hour postinjection and repeated at 2 to 4 hours postinjection. A positive study showed an increased isotope uptake in the right lower quadrant. Nineteen patients had histologically proven appendicitis. Three of these patients were excluded because they were operated on before scan completion. Thirteen of the remaining 16 patients with appendicitis had positive studies (false negative rate = 19%). All patients without appendicitis had either negative scans or scans that detected other intra-abdominal diseases, such as diverticulitis, tubo-ovarian abscess, or small bowel infarction (false positive rate = 0%). Overall, this Tc-99 HMPAO study had a sensitivity of 81 per cent, a specificity of 100 per cent and an overall accuracy of 89 per cent. The 4-hour Tc-99 HMPAO WBC scan is a useful, noninvasive test for confirming the clinical diagnosis of acute appendicitis, but it may prove more valuable as a diagnostic study to rule out appendicitis in patients that have abdominal pain of unclear etiology.

Topics: Acute Disease; Adolescent; Adult; Aged; Appendicitis; California; Diagnosis, Differential; Evaluation Studies as Topic; Female; Humans; Isotope Labeling; Leukocytes; Male; Middle Aged; Organotechnetium Compounds; Oximes; Preoperative Care; Radionuclide Imaging; Reproducibility of Results; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Ultrasonography