Immunoscintigraphy performed with In-111-labeled CYT-103 in the management of colorectal cancer: comparison with CT.

Immunoscintigraphy performed after intravenous administration of indium-111-labeled CYT-103, an immunoconjugate of monoclonal antibody B72.3, was evaluated in patients with suspected primary or recurrent colorectal cancer at 25 centers in the United States. Gamma camera imaging, computed tomography (CT), and confirmatory surgical exploration were completed in 169 of 227 patients who received single infusions of In-111 CYT-103. Eight patients (3.5%) had reversible, nonserious adverse reactions, and 39% developed antimurine antibodies. Surgery revealed that 155 of 169 patients had colorectal carcinoma. In these 155 patients, immunoscintigraphy and CT demonstrated similar sensitivity (69% and 68%, respectively) and specificity (77%). However, immunoscintigraphy had greater sensitivity in detection of pelvic tumors (74% vs 57%, P = .035) and extrahepatic abdominal tumors (66% vs 34%, P less than .001); CT enabled detection of a greater proportion of liver metastases (84% vs 41%, P less than .001). These results indicate that In-111 CYT-103 can be administered safely and that immunoscintigraphy performed with this agent frequently enables identification of extrahepatic abdominal sites of disease not visualized with CT.

Indium-111 monoclonal antibody B72.3 scintigraphy in colorectal cancer. Correlation with computed tomography, surgery, histopathology, immunohistology, and human immune response.

As part of an open-labeled nonrandomized multi-institutional Phase III study, the authors compared the results of In-111 (In-111) B72.3 glycyl-tyrosyl-n-diethylenetriaminepentaacetic acid lysine (GYK-DTPA) monoclonal antibody scintigraphy with computed tomography (CT), surgery, histopathology, immunohistology, and human antibody response in 23 patients with primary colorectal carcinoma. There were no significant adverse reactions to 1 mg of In-111-labeled antibody. Planar imaging identified 16 of 23 primary colon lesions, whereas single photon emission computer tomography (SPECT) imaging identified 21. SPECT also correctly identified lymphatic involvement in four patients. (There were two false-positive results.) Liver metastases were identified with SPECT imaging. Twenty-six percent of patients developed human anti-mouse antibody (HAMA). These preliminary results demonstrate that In-111 B72.3 GYK-DTPA is a safe monoclonal antibody conjugate that has a high sensitivity for identifying primary colorectal cancer. Regional lymphatic and distant liver metastases also can be imaged, but false-positive results can occur.

Imaging techniques for identifying parathyroid tumors.

Recent advances in imaging techniques, including high-resolution sonography, parathyroid scintigraphy, computerized tomography, magnetic resonance imaging, venography and venous sampling, arteriography, and fine-needle aspiration biopsy, have made it possible consistently to identify parathyroid glands enlarged owing to adenoma formation, diffuse hyperplasia, or carcinoma. Whereas the routine use of these techniques in the previously unoperated patient with suspected hyperparathyroidism is debated, most experts would agree to their utility in patients with prior negative neck exploration in whom elevated serum calcium and parathyroid hormone persist.

Clinical and radiological evaluation of Vertebrace extrication collars.

An aid for prehospital cervical immobilization was studied radiographically. We applied the Vertebrace Extrication Collar to ten volunteers and measured cervical movement in the sagittal plane. Results of mean degrees of flexion-extension and mean percentage of restricted motion at each level compared favorably with results of earlier studies using rigid orthoses (the four-poster brace, Cervicothoracic, Somi Brace, and Yale collar). A second method of analysis, measuring relative motion of vertebral segments by level, found no flexion displacement in 70% and no extension displacement in 60% at C5-C6. The Vertebrace Collar proved to be effective in restricting movement of the cervical vertebrae most often injured following serious trauma.

Parathyroid imaging.

Advances in diagnostic imaging methods during the last decade have facilitated the identification of focal or diffuse parathyroid abnormalities. Major advances have included improvements in computed tomography and high-resolution ultrasonography, and the introduction of thallium-201-technetium-99m parathyroid subtraction scintigraphy. The more invasive methods of venous sampling and selective angiography have also been refined, but they have not been used as extensively because of the need for highly skilled personnel. The role of these diagnostic tools before surgery in the routine evaluation of patients with suspected primary hyperparathyroidism is unclear because a skilled surgeon should be able to achieve cures in 90% of these patients during exploratory surgery. However, most physicians would agree that, in those patients whose abnormalities go undetected during exploratory surgery of the neck, diagnostic imaging methods should be used before additional surgery is planned. Further prospective studies are needed to determine if routine localization before surgery is cost effective.

Radionuclide imaging of parathyroid tumors: historical perspectives and newer techniques.

The increasing use of automated blood chemistry screens for serum calcium levels along with improved methods in measuring parathyroid hormone (PTH) levels have made the diagnosis of parathyroid disease a common clinical problem. Parathyroid adenomas account for the majority of primary hyperparathyroidism with diffuse hyperplasia and parathyroid carcinoma occurring less frequently. Early scintigraphic techniques to identify enlarged parathyroids used selenomethionine-75 which was considered to be incorporated into PTH. In general, the sensitivity of scanning the neck using this tracer was related to the size of the enlarged parathyroid, but in large series, the overall sensitivity was less than 50%. Recent work by Ferlin et al, using a Technetium-99m/Thallium-201 subtraction scintigraphic technique has yielded a sensitivity of 92% in identifying pathologically enlarged parathyroid glands. Winzelberg et al modified this technique to allow imaging the mediastinum plus simplifying the subtraction method. In a prospective study with high-resolution sonography, similar sensitivities and specificities were found with sonography and scintigraphy. Tl-201/Tc-99m pertechnetate subtraction scintigraphy appears to be an accurate technique in identifying pathologic parathyroid enlargement. Its ultimate role in the evaluation of patients with suspected hyperparathyroidism still needs to be determined.

Parathyroid adenomas evaluated by Tl-201/Tc-99m pertechnetate subtraction scintigraphy and high-resolution ultrasonography.

Thallium-201/technetium-99m pertechnetate subtraction scintigraphy of the parathyroid glands was performed in a prospective study of 33 patients who had undergone bilateral neck exploration for elevated serum calcium and serum parathyroid hormone levels. In 31 cases, the Tl-201/Tc-99m subtraction technique yielded an overall sensitivity of 81%, specificity of 99%, and accuracy of 94% for identifying solitary parathyroid adenomas. Tl-201/Tc-99m subtraction scintigraphy correctly identified 73% of parathyroid adenomas weighing less than 499 mg, 79% of those weighing 500-1,499 mg, and 100% of adenomas weighing more than 1,500 mg. In a subgroup of 24 patients with solitary parathyroid adenomas who underwent both scintigraphy and high-resolution sonography, the sensitivity, specificity, and accuracy of both procedures were similar.

Computed tomographic evaluation of compression of the superior vena cava and its tributaries.

Observations on computed tomography (CT) of 15 patients with compression of the superior vena cava (SVC) and its tributaries are reported and compared with clinical, radiographic and surgical findings. The site of compression in 14 patients was accurately determined by CT, which could delineate the presence of intraluminal clot and extrinsic compression of venous structures, as well as associated mediastinal masses. Collateral superficial vessels were identified in nine patients with contrast-enhanced scans. Contrast-enhanced mediastinal and chest CT was shown to provide detailed anatomic and physiologic information about the etiology of SVC syndrome.

Parathyroid adenomas studied by digital subtraction angiography.

Eighteen patients who had elevated serum calcium and parathormone levels were prospectively studied with intravenous digital subtraction angiography (DSA). Intravenous DSA of the neck and mediastinum was performed in the anteroposterior, the left anterior, and the right anterior oblique projections. The study was considered positive if an abnormal blush or blood supply was noted. Upon operation, 14 patients were confirmed to have parathyroid adenomas, of whom five had positive preoperative DSA examinations. Four patients were followed medically (three negative DSA, one positive DSA). A positive intravenous DSA may be useful to guide neck explorations for parathyroid adenomas; however, the low sensitivity of the study may limit its screening potential.

Patients with hemoptysis examined by Tc-99m sulfur colloid and Tc-99m-labeled red blood cells: a preliminary appraisal.

A prospective study of 16 patients with hemoptysis was conducted over a 2 1/2-year period. Technetium-99m sulfur colloid (Tc-SC) and technetium-99m-labeled red blood cells (Tc-RBC) were sequentially used to identify the general area of bleeding. Tc-SC accurately located the bleeding area in 3 patients and Tc-RBC identified the bleeding area in 8; there were no false-positive studies. Tc-SC scans were positive at 6-10 minutes and all patients had positive Tc-RBC studies. In general, the scans accurately located the source of bleeding as determined by bronchoscopy and/or surgery. Because of the small sample, statistically significant differences between both techniques were not ascertained. Both Tc-SC and Tc-RBC may prove to be helpful, minimally invasive imaging procedures for determining the general area of hemorrhage in patients with clinically significant hemoptysis. Although a trend suggests that Tc-RBC is a more sensitive method, further comparison is needed for corroboration.