Development of new markers for hypoxic cells: [131I]Iodomisonidazole and [131I]Iodoerythronitroimidazole

This study was aimed at developing ligands to evaluate tumor hypoxia by planar scintigraphy. Two 2-nitroimidazole analogues were developed as precursor compounds to image hypoxic tumors. Both tosylmisonidazole (Ts MISO) and tosylerythronitroimidazole (Ts ETNIM) were labeled with 131I. The biodistribution and autoradiographic evaluations by planar scintigraphy of 131I-IMISO and 131I-IETNIM were conducted at 1, 2 and 4 hours after administration to rats bearing 13762 breast tumors. Biodistribution of 131I-IMISO was also evaluated in Madison lung tumor-bearing mice. Intratumoral oxygen tension was measured by the Eppendorf system. Biodistribution showed similar tumor/blood and tumor/muscle count density ratios for both compounds. The thyroid uptake of both analogues was increased with time, suggesting in vivo deiodination probably occurred. Autoradiographs of 131I-IMISO and 131I-IETNIM revealed good visualization of the neoplasms. The tumor oxygen tension was 3-6 mmHg as compared to the normal tissue oxygenation of 30-40 mmHg. The findings indicate that these analogues can localize in the hypoxic region of solid tumors and may assist with quantitation of the hypoxic fraction of tumor for proper selection and evaluation of appropriate radiotherapy and chemotherapy.

Recurrent ovarian endodermal sinus tumor: demonstration by computed tomography, magnetic resonance imaging, and positron emission tomography

We report a case of recurrent endodermal sinus tumor of the ovary that was identified and/or clearly depicted by computed tomography, magnetic resonance imaging, and positron emission tomography. The potential roles of various imaging modalities in the detection of recurrent endodermal sinus tumor are discussed.

Positron emission tomography in the detection of residual laryngeal carcinoma

Positron emission tomography measures the metabolic activity of tissue. Because metabolism rates are higher in tumors than in normal tissue, positron emission tomography can be used to identify abnormal tissue. Positron emission tomography has proved useful in detecting residual or recurrent tumor in the brain and gastrointestinal tract after definitive treatment. We selectively used positron emission tomography in a preliminary trial to examine patients with laryngeal cancer who had previously been treated with organ-preservation therapy with radiation therapy alone or in combination with induction chemotherapy. These patients are often difficult to examine both clinically and radiographically because of posttreatment edema and fibrosis. From 1991 to 1993 patients at our institution who were treated with either radiation therapy or a combination of induction chemotherapy and radiotherapy for laryngeal carcinoma were evaluated after treatment. If clinical examination was suspicious for residual tumor or recurrence, a computed tomography or magnetic resonance imaging scan was obtained. In 10 patients neither clinical examination nor conventional imaging could absolutely rule out residual/recurrent carcinoma. In these patients positron emission tomography with 2-fluoro-2-deoxy-D-glucose was used to detect disease. The results from positron emission tomography were compared with the results from subsequent biopsy (five patients) or clinical follow-up. Positron emission tomography had a sensitivity of 67% and a specificity of 57%. The positive predictive value of positron emission tomography was 67%. The negative predictive value of positron emission tomography was 80%.(ABSTRACT TRUNCATED AT 250 WORDS)

Positron Emission Tomography in the Detection of Residual Laryngeal Carcinoma

Positron emission tomography measures the metabolic activity of tissue. Because metabolism rates are higher in tumors than in normal tissue, positron emission tomography can be used to identify abnormal tissue. Positron emission tomography has proved useful in detecting residual or recurrent tumor in the brain and gastrointestinal tract after definitive treatment. We selectively used positron emission tomography in a preliminary trial to examine patients with laryngeal cancer who had previously been treated with organ-preservation therapy with radiation therapy alone or in combination with induction chemotherapy. These patients are often difficult to examine both clinically and radiographically because of posttreatment edema and fibrosis. From 1991 to 1993 patients at our institution who were treated with either radiation therapy or a combination of induction chemotherapy and radiotherapy for laryngeal carcinoma were evaluated after treatment. If clinical examination was suspicious for residual tumor or recurrence, a computed tomography or magnetic resonance imaging scan was obtained. In 10 patients neither clinical examination nor conventional imaging could absolutely rule out residual/recurrent carcinoma. In these patients positron emission tomography with 2-fluoro-2-deoxy-D-glucose was used to detect disease. The results from positron emission tomography were compared with the results from subsequent biopsy (five patients) or clinical follow-up. Positron emission tomography had a sensitivity of 67% and a specificity of 57%. The positive predictive value of positron emission tomography was 67%. The negative predictive value of positron emission tomography was 80%. Positron emission tomography may offer the clinician a useful diagnostic tool for cancer surveillance in organ-sparing treatment protocols for patients with laryngeal cancer.

Different biologic features of desmoid tumors in adult and juvenile patients: MR demonstration

OBJECTIVE

To demonstrate different biologic features of desmoid tumors on MRI between juvenile and adult patients.

MATERIALS AND METHODS

We have retrospectively analyzed clinical records and 121 MRI findings in 40 patients (8 juveniles and 32 adults) with proven desmoid tumors. The Fisher exact test and Kaplan-Meier curve were utilized for statistical analysis.

RESULTS

Recurrences in the juvenile patients were more multiple (50 vs 12%) and appeared significantly earlier than in the adult patients. Adult patients demonstrate a much greater recurrence-free rate (p = 0.0001). Infiltrative pattern was significantly predominant in the juvenile patients (63%) whereas the nodular pattern was more frequent in the adult patients (81%). Low-signal intensity zones on T1- and T2-weighted imaging as well as the type of contrast enhancement did not show any significant relationship with biological behavior. Four cases with no significant contrast enhancement showed low signal intensities on T2-weighted imaging.

CONCLUSION

Magnetic resonance demonstrates different biologic features between juvenile and adult patients with histologically same desmoid tumors. These differences may be useful in consideration of MRI follow-up studies.

X-ray structure of calcineurin inhibited by the immunophilin-immunosuppressant FKBP12-FK506 complex

The X-ray structure of the ternary complex of a calcineurin A fragment, calcineurin B, FKBP12, and the immunosuppressant drug FK506 (also known as tacrolimus) has been determined at 2.5 A resolution, providing a description of how FK506 functions at the atomic level. In the structure, the FKBP12-FK506 binary complex does not contact the phosphatase active site on calcineurin A that is more than 10 A removed. Instead, FKBP12-FK506 is so positioned that it can inhibit the dephosphorylation of its macromolecular substrates by physically hindering their approach to the active site. The ternary complex described here represents the three-dimensional structure of a Ser/Thr protein phosphatase and provides a structural basis for understanding calcineurin inhibition by FKBP12-FK506.

Comparison of nuclear bone and gallium scans in the therapeutic evaluation of bone lymphoma

The objective of this study was to compare Tc-99m MDP bone and Ga-67 scans for the therapeutic response to bone lymphoma in 40 patients. The authors retrospectively compared 40 Tc-99m MDP bone scans and 20 Ga-67 scans before therapy, 29 bone scans and 13 Ga-67 scans during the therapy, and 33 bone scans and 15 Ga-67 scans after therapy. Tc-99m MDP and Ga-67 whole body scans were obtained within 2 weeks of each study and were graded visually (grades 1-4) in which grade 3 means similar count density to that of normal iliac alar activity on bone scans and normal liver activity on Ga-67 scans, respectively. The findings of lesion improvement during and after therapy were found in 66.0% (19 of 29) and 72.7% (24 of 33) with Tc-99m MDP bone scans, 84.6% (11 of 13) and 86.7% (13 of 15) with Ga-67 scans, respectively. The mean grades of Tc-99m MDP uptake were 3.06 before, 2.34 during, and 1.75 after therapy. The mean grades of Ga-67 uptake were 3.22 before, 1.42 during, and 1.30 after therapy. Ga-67 scans appear to be more reliable than Tc-99m MDP bone scans in evaluating the therapeutic response of bone lymphoma.

In-111 DTPA Ommayagrams in leptomeningeal carcinomatosis

Radionuclide Ommayagrams in 25 patients with leptomeningeal carcinomatosis were performed after injection of 0.5 mCl of In-111 DTPA into Ommaya shunt reservoirs to evaluate cerebrospinal fluid-shunt communication, detect the blockage of the cerebrospinal fluid pathway, evaluate the cerebrospinal fluid flow pattern, and predict the distribution of the chemotherapeutics. All results were correlated with MRI evaluations of the brain and spine, as well as clinical findings. Radionuclide Ommayagrams were found to be 73% sensitive and 100% specific in the evaluation of cerebrospinal fluid space disease. MRI of the spine and head was found to be 100% sensitive, but 86% specific for obstructive cerebrospinal fluid space disease.

Detecting recurrent or residual lung cancer with FDG-PET

We investigated the diagnostic accuracy of FDG-PET in the detection of recurrent lung cancer.

METHODS

Thirty-nine lesions in 38 patients with clinically suspected recurrent or residual lung cancer were studied with PET. All PET images were visually interpreted in conjunction with thoracic CT or MRI. Semiquantitative analysis using standardized uptake values (SUVs) was also performed in 25 lesions. FDG-PET diagnoses were correlated with pathological diagnoses and clinical outcome.

RESULTS

The sensitivity and specificity of FDG-PET for detecting recurrent tumors were 100% (26/26) and 61.5% (8/13), respectively. The difference in mean SUV between recurrent tumors and noncancerous lesions was statistically significant [11.2 +/- 5.7 (n = 16) vs. 3.5 +/- 1.8 (n = 9), p < 0.0001]. False-positive results showed relatively lower SUVs than true-positives and also demonstrated increased uptake in a curvilinear rather than nodular shape.

CONCLUSION

FDG-PET is useful for detecting recurrent lung cancer after treatment. False-positive diagnoses might be reduced by analysis of uptake shape and serial changes in SUV, but further study is needed.

Radioimmunoscintigraphy in the differential diagnosis of hepatic mass lesion

A patient with suspected recurrent cancer of the colon underwent a variety of imaging procedures for the differential diagnosis of a hepatic mass lesion. Computed tomography (CT) showed a low-density lesion in the left hepatic lobe, and the initial CT-guided biopsy of the liver mass was reported to demonstrate a benign lesion. Ultrasonography (US) showed a hypoechoic lesion, and technetium-99m red blood cell (RBC) scan failed to suggest a hemangioma. However, radioimmunoscintigraphy (RIS) using 99mTc- labeled anti-carcinoembryonic antigen (CEA) monoclonal antibody clearly demonstrated increase uptake of antibody in the liver lesion. Scheduled hepatic angiography was canceled and subsequent exploratory laparotomy confirmed liver metastasis. RIS appears most helpful in the diagnosis of hepatic metastasis in patients with colorectal cancer and a rising CEA level. CT, US, and 99mTc-RBC studies for the investigation of hepatic masses are briefly discussed.

Development of F-18-labeled fluoroerythronitroimidazole as a PET agent for imaging tumor hypoxia

PURPOSE

To develop a hydrophilic ligand to image tumor hypoxia at positron emission tomography (PET).

MATERIALS AND METHODS

Biodistribution of fluorine-18-labeled fluoroerythronitroimidazole (FETNIM) and F-18-labeled fluoromisonidazole (FMISO) was determined at PET and autoradiography in three mammary-tumor-bearing rats. The partition coefficient of FETNIM, FMISO, and misonidazole was determined.

RESULTS

Biodistribution of F-18-labeled FETNIM at 1, 2, and 4 hours showed tumor-to-blood ratios of 2.29 +/- 0.599, 2.41 +/- 0.567 and 8.02 +/- 2.420, respectively, and tumor-to-muscle ratios of 0.66 +/- 0.267, 2.11 +/- 0.347, and 5.92 +/- 2.240, respectively. The tumor-to-blood count density ratio with F-18-labeled FETNIM at 4 hours after injection was significantly higher than with F-18-labeled FMISO. Autoradiographs indicated that both agents could help differentiate hypoxic versus necrotic region in the tumor.

CONCLUSION

F-18-labeled FETNIM can help detect tumor hypoxia and is easier to prepare, less costly, and more hydrophilic than F-18-labeled FMISO.

Primary breast lymphoma detected with SPECT using gallium-67-citrate

Breast involvement by malignant lymphoma either as a primary site or as a secondary site from lymphoma elsewhere is rare. Primary breast lymphoma (PBL) accounts for only a small percentage of total malignant lymphoma involving the breast. The incidence of PBL varies from 0.004% to 0.5%. We present a case of PBL which was well demonstrated on total-body imaging as well as SPECT using 67Ga-citrate.

MR characteristics of epithelioid sarcoma

OBJECTIVE

The purpose of this study was to characterize MRI findings of epithelioid sarcomas and correlate them with the presence or absence of metastasis and/or recurrence.

MATERIALS AND METHODS

Thirty-six MRI studies were analyzed retrospectively in 12 patients with histologically proven epithelioid sarcomas. The following parameters were evaluated: lesion location, signal characteristics, and bone or vascular involvement. Also, the time of the appearance and the frequency of local recurrences were determined, as well as location, frequency, and timing of appearance of metastatic disease.

RESULTS

Epithelioid sarcomas were located mainly in the upper extremities (58%). The MRI findings divided the tumor into two major categories: hemorrhagic (two patients) and nonhemorrhagic (ten patients). The study showed recurrence in 33% of the cases and metastasis in 50% overall. Both patients with hemorrhagic epithelioid sarcoma showed metastases that appeared earlier than metastases from nonhemorrhagic sarcomas. Only 33% of the nonhemorrhagic sarcomas showed metastases; and 17% of the cases revealed vascular invasion.

CONCLUSION

Magnetic resonance plays a role in recognizing intratumoral hemorrhage in patients with epithelial sarcoma. Patients with hemorrhagic tumors need more aggressive treatments and follow-up studies.

MRI of recurrent cystic mesothelioma: differential diagnosis of cystic pelvic masses

A case of recurrent cystic pelvic mesothelioma in a woman who developed pelvic fullness, frequent urination, and pressure sensation in the lower abdomen with interesting magnetic resonance imaging findings is presented. The differential diagnosis of cystic pelvic masses is briefly discussed.

Structure and mechanism of interleukin-1 beta converting enzyme

Interleukin-1 beta converting enzyme (ICE) processes an inactive precursor to the proinflammatory cytokine, interleukin-1 beta, and may regulate programmed cell death in neuronal cells. The high-resolution structure of human ICE in complex with an inhibitor has been determined by X-ray diffraction. The structure confirms the relationship between human ICE and cell-death proteins in other organisms. The active site spans both the 10 and 20K subunits, which associate to form a tetramer, suggesting a mechanism for ICE autoactivation.

Androgen-independent cancer progression and bone metastasis in the LNCaP model of human prostate cancer

Our laboratory has previously reported on the derivation of LNCaP cell sublines from LNCaP tumors maintained in castrated and intact athymic male mice. These LNCaP sublines differ from the parental line in tumorigenicity and androgen dependence. This paper demonstrates that one of these sublines acquired metastatic potential. When inoculated either s.c. or orthotopically, the C4-2 subline metastasized to the lymph node and bone with an incidence of 11-50%. Interestingly, the incidence of osseous metastasis was higher in castrated than in intact male hosts. We evaluated the chromosomal, immunohistochemical, and biochemical characteristics of the LNCaP sublines derived from C4-2 tumors that metastasized to the lymph node and bone. Cytogenetic analysis showed that all sublines were human and shared common marker chromosomes with the parental LNCaP cells. This experimental human prostate cancer model may permit, for the first time, the study of the molecular mechanisms underlying human prostate cancer metastasis.

Imaging, biodistribution and therapy potential of halogenated tamoxifen analogues

Tamoxifen binds to estrogen receptors (ERs) and prevents breast cancer cell proliferation. This study is aimed at developing a ligand for imaging ER (+) breast tumors by positron emission tomography (PET) or single photon emission computed tomography (SPECT). [18F]-Labeled tamoxifen analogue ([18F]FTX) was prepared in 30-40% yield and [131I]-labeled tamoxifen analogue ([131I]ITX) was prepared in 20-25% yield. In mammary tumor-bearing rats, the biodistribution of [18F]FTX at 2 h showed a tumor uptake value (% injected dose/gram tissue) of 0.41 +/- 0.07; when rats were pretreated with diethylstilbestrol (DES), the value changed to 0.24 +/- 0.017. [131I]ITX at 6 h showed a tumor uptake value of 0.26 +/- 0.166; when rats were pretreated with DES, the value changed to 0.22 +/- 0.044. Priming tumor-bearing rats with estradiol, a tumor uptake value for [131I]ITX was increased to 0.48 +/- 0.107 at 6 h. In the [3H]estradiol receptor assay, tumors had a mean estrogen receptor density of 7.5 fmol/mg of protein. In gamma scintigraphic imaging studies with [131I]ITX, the rabbit uterus uptake can be blocked by pretreatment with DES. Both iodo-tamoxifen and tamoxifen reduced ER(+) breast tumor growth at the dose of 50 micrograms in tumor-bearing mice. The findings indicate that tamoxifen analogue uptake in tumors occurs via an ER-mediated process. Both analogues should have potential for diagnosing functioning ER(+) breast cancer.

Extraosseous multiple myeloma: imaging features

Multiple myeloma is a disseminated malignant neoplasm usually derived from a single clone of plasma cells. Patients with myeloma have diverse signs such as anemia, hypercalcemia, uremia, pathologic fractures, and recurrent infections. Extraosseous manifestations are found in less than 5% of patients with multiple myeloma. They can arise in any tissue, and their presence has been associated with more aggressive disease. The purpose of this essay is to illustrate the imaging findings of extraosseous myeloma and heighten awareness of this unusual manifestation of multiple myeloma.

Nuclear hepatobiliary imaging

Recent improvements in hepatobiliary radiopharmaceuticals and the high prevalence of biliary tract disease have resulted in a larger role for hepatobiliary imaging in clinical applications. The use of hepatobiliary imaging in assessing hepatic blood flow, hepatocyte function, biliary drainage, and complications in patients with jaundice or abdominal pain or surgery, as well as its primary use in diagnosing acute cholecystitis, is discussed.

Positron emission tomography with fluorine-18-deoxyglucose in the detection and staging of breast cancer

BACKGROUND

An increasing number of patients with breast cancer is being treated with preoperative chemotherapy. Evaluation of treatment response may be facilitated by positron emission tomography (PET) with 18F-fluoro-2-deoxy-D-glucose (FDG). This noninvasive technique may allow prediction of the chemotherapy outcome in an early phase of the treatment.

METHODS

Prerequisites for treatment monitoring with PET are good FDG uptake in the tumor, high specificity, and a reliable quantification technique. These factors were studied in 20 patients with primary breast cancer, lymph node metastases, benign breast lesions, a combination of these abnormalities, or no abnormality.

RESULTS

In 10 of 11 patients with primary breast cancer, the tumor was visualized. The median tumor-to-normal-tissue-uptake ratio was 4.9. In all five patients with increased uptake in the lymph node basin, pathologic proof of metastatic cancer was found. Of the patients with benign or no disease of the breast, slightly increased uptake was seen in one patient with fibrocystic disease.

CONCLUSION

It is concluded that PET with FDG can be used for breast cancer imaging and staging.

MRI of extraskeletal osteosarcoma

We report four cases of extraskeletal osteosarcoma of the thigh to illustrate MRI findings of this rare neoplasm. Calcifications or osteoid material were not discernible in these tumors on MRI or conventional radiography. Three tumors were well demarcated on MRI and corresponded to pseudoencapsulation on radiologic-pathologic correlation. These three tumors were heterogeneous in appearance and were hyperintense to muscle on T1-weighted imaging and demonstrated high signal intensity on T2-weighted imaging. In the fourth tumor, which occupied almost the entire thigh, MRI before and after intravenous gadopentetate dimeglumine administration revealed cystic, hemorrhagic, and solid components. Pathological examination revealed a cystic hemorrhagic cavity containing necrotic and viable tumor and a large solid tumor component. The MRI findings in extraskeletal osteosarcoma are non-specific. However, in the appropriate age group the differential diagnosis of a soft-tissue mass in the thigh should include extraskeletal osteosarcoma, even in the absence of radiographically discernible calcifications or osteoid material within the soft-tissue mass.