technetium-tc-99m-exametazime and indium-tris(tropolonate)

Evidence is now accumulating that patient medication can adversely affect the radiolabelling of white cells. We have undertaken a survey for the years 1981-97 to examine instances of unusually low labelling efficiencies of 111In-tropolone and 99Tcm-HMPAO labelled white cells. Respondents were asked to ascertain which drugs were being taken on the day of the test. Fifty adverse reports were received during that period. Many patients were taking drugs which are known to affect white cell function, including cephalosporins, azathioprine, prednisolone, cyclophosphamide, nifedipine, suphasalazine, iron salts and heparin. Using Bradford-Hill's criteria to assess whether an association between two variables is also one of causation, it was found that there was a high probability that the above drugs caused the low labelling efficiencies.

Topics: Drug Interactions; Drug Therapy; Humans; Indium Radioisotopes; Leukocytes; Organometallic Compounds; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tropolone

Fifty patients with suspected intra-abdominal abscess were investigated prospectively with ultrasound and with 99mTc-hexamethylpropylene-amine oxime (HMPAO) isotope labelled mixed leucocytes, using 111-In tropolonate granulocyte scanning as the reference standard. Twenty five patients had inflammatory bowel disease (three were postoperative): 21 of these had Crohn's disease and four had ulcerative colitis. The remainder comprised nine with postoperative fever and 16 with fever and abdominal pain. An abscess was diagnosed when focal activity on serial 111-In tropolonate and 99m-Tc-HMPOA images at one, three, and 24 hours resulted in activity at least equal to liver activity at 24 hours. Thirteen abscesses were diagnosed using each type of white cell scanning, resulting in 100% sensitivity for 99m-Tc-HMPAO compared with 111-In tropolonate. Bowel inflammation was easily distinguished from abscess on serial images. Eight of these 13 abscesses were detected by ultrasound. Altogether 17 abscesses were found. Ultrasound detected 12, including four liver abscesses which were not purulent and had not been detected by white cell scanning. Ultrasound had a sensitivity of 71% (12 of 17) and a specificity of 87% (33 of 38) using all confirmed abscesses as the reference standard. White cell scanning showed a sensitivity of 76% (13 of 17: as a result of the four non-purulent liver abscesses) and a specificity of 100%. 99m-Tc-HMPAO scanning is as accurate as 111-In tropolonate scanning, and has several advantages including simplicity, availability, superior image quality, and reduced radiation dose. Both methods are more sensitive and specific than ultrasound for intra-abdominal abscess detection but ultrasound is advisable if a neutrophil infiltrate is not suspected.

Topics: Abdominal Abscess; Adolescent; Adult; Aged; Aged, 80 and over; Colitis, Ulcerative; Crohn Disease; Female; Granulocytes; Humans; Indium Radioisotopes; Leukocytes; Male; Middle Aged; Organometallic Compounds; Organotechnetium Compounds; Oximes; Prospective Studies; Radionuclide Imaging; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tropolone; Ultrasonography

In a prospective comparative study of 14 patients with inflammatory bowel disease (IBD), the abilities of 99mTc-HMPAO labeled white blood cells (WBCs) and 111In-granulocytes to assess the presence and location of active disease were compared. The two examinations were carried out within 2 wk of each other. Scintigraphically concordant positive or discordant segments were evaluated by radiologic or endoscopic examination performed within 14 days. When bowel segments were compared, concordance was found for 102/111 (91.8%) segments between 99mTc-WBC images obtained at 1 hr after injection and 3-hr 111In-granulocyte images. For five of five 99mTc-WBCs positive/111In-granulocyte negative segments, it could be proven that the 99mTc-WBC result was caused by active disease. For patients, 99mTc-WBC scintigraphy detected four more patients with active disease than 111In-granulocytes (11 and 7 patients, respectively). Technetium-WBCs was superior in the assessment of active disease, especially for small bowel segments. We conclude that early imaging 1 hr after the injection of 99mTc-WBCs can reliably replace 111In-granulocyte scintigraphy in IBD patients because the radiopharmaceutical is available on a daily basis. Thus, there is less radiation burden to the patient and cell separation is simpler and less time-consuming.

Topics: Adult; Colitis, Ulcerative; Crohn Disease; Female; Granulocytes; Humans; Indium Radioisotopes; Leukocytes; Male; Organometallic Compounds; Organotechnetium Compounds; Oximes; Prospective Studies; Radionuclide Imaging; Technetium Tc 99m Exametazime; Tropolone

Topics: Animals; Blood Platelets; Cattle; Cell Survival; Escherichia coli Infections; Humans; Indium Radioisotopes; Isotope Labeling; Lipids; Mice; Organometallic Compounds; Organotechnetium Compounds; Osteomyelitis; Oximes; Pyridines; Rabbits; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Solubility; Technetium Tc 99m Exametazime; Thiones; Tissue Distribution; Tropolone

Topics: Chromosome Aberrations; Humans; Indium Radioisotopes; Isotope Labeling; Kinetics; Leukemia, Lymphocytic, Chronic, B-Cell; Lymphocytes; Lymphoma, Non-Hodgkin; Organometallic Compounds; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tropolone

Two weeks after the introduction of osteomyelitis in three dogs, autologous leukocytes were dual-labeled with both [99mTc]HM-PAO and [111In]tropolonate, and reinjected. Blood sampling and imaging were then performed. Two weeks later, the same dogs received simultaneous injections of singly-labeled [99mTc]WBC and [111In]WBC for comparison. For both studies, blood samples were drawn over 6 hr to determine the respective blood clearance half-time (TB) and % recovery (%R0) of cell-bound radioactivity. There were no significant differences in the average TB results of the 99mTc and 111In groups, either within or between the dual- and singly-labeled studies. The %R0 of singly-labeled [99mTc]WBC was about half that of the other groups (p less than 0.01); however, this difference was attributed to the dissimilar radiochemical purity of the [99mTc]HM-PAO reagents. Region of interest analysis of the 6 and 24 hr images revealed no significant differences between either cell label in the relative or absolute in vivo uptake at known sites of osteomyelitis, noninfected surgery, and normal bone marrow.

Topics: Animals; Cycloheptanes; Dogs; Indium Radioisotopes; Leukocytes; Organometallic Compounds; Osteomyelitis; Oximes; Radionuclide Imaging; Technetium; Technetium Tc 99m Exametazime; Tropolone

The lipophilic complex, 99Tcm-hexamethylpropyleneamine oxime (HMPAO) is an efficient leucocyte label, and labels granulocytes with more stability than mononuclear leucocytes. The recovery of 99Tcm-HMPAO granulocytes, expressed as the percentage of injected granulocyte-associated activity circulating as granulocyte-associated activity 40-45 min after injection, was 37% (S.E. 3%), similar to the recovery of 111In-labelled granulocytes isolated and labelled in plasma using tropolone. The T1/2 of 99Tcm-HMPAO labelled granulocytes in blood was 4.4 h (S.E. 0.4 h), less than that of 111In-labelled granulocytes, although when a correction was made for 99Tcm elution, it was 6.4 h. The initial biodistribution of 99Tcm-labelled leucocytes was similar to 111In-labelled granulocytes, with a rapid initial lung transit, prominent splenic activity, bone marrow activity and minimal hepatic activity, although, unlike 111In, 99Tcm activity was also seen in urine, occasionally in the gallbladder, and, from about 4 h, consistently in the colon. Bone marrow activity was particularly prominent with 99Tcm. About 6% of 99Tcm was excreted in the faeces up to 48 h after injection, and about 17% in urine up to 24 h. The time-activity curves of reticuloendothelial activity up to 24 h were broadly similar for the two labelled cell preparations, and the differences that were observed can be explained on the basis of a higher rate of 99Tcm elution. Clinical information given by the two agents was similar in 27 of 30 patients who received both. Of the three who gave different information, one received 111In-labelled granulocytes which were considered to be functionally suboptimal and two, with inflammatory bowel disease, showed different distributions of abnormal bowel activity. We conclude that with respect to granulocyte kinetics and clinical data, 99Tcm-HMPAO labelled leucocytes are comparable with 111In-tropolonate labelled granulocytes.

Topics: Colitis, Ulcerative; Crohn Disease; Cycloheptanes; Female; Granulocytes; Humans; Indium Radioisotopes; Inflammation; Leukocytes; Male; Organometallic Compounds; Oximes; Radionuclide Imaging; Technetium; Technetium Tc 99m Exametazime; Tissue Distribution; Tropolone