Evaluation of preoperative chemotherapy using PET with fluorine-18-fluorodeoxyglucose in breast cancer

We retrospectively investigated the value of PET with fluorine-18 fluorodeoxyglucose (FDG) for preoperative chemotherapy response in patients with locally advanced breast cancer.

METHODS

FDG-PET studies were performed on 16 consecutive patients. All patients had PET studies before chemotherapy, 13 patients between the end of the first cycle and at the midpoint of chemotherapy, and 14 patients before surgery. Visual diagnoses and the standardized uptake values (SUV) of PET scans were compared with pathology findings at surgery and with the results of mammography, ultrasonography (US) or both, which were performed before chemotherapy and before local surgery for residual disease. Each patient's clinical course was monitored for up to 3 yr.

RESULTS

Sensitivity for detection of pathologically proven primary lesions was 100%, 62.5% and 87.5% with FDG-PET, mammography and US, respectively; and sensitivity for detection of initial nodal involvement was 77%, 70% and 87.5%, respectively. Sensitivity for detection of residual primary tumor was 75%, 71.4% and 87.5%, respectively; and sensitivity for detection of residual nodal involvement was 41.6%, 71.4% and 66.6%, respectively. The mean SUV value of primary lesions was 9.4 (range 2.0-20.7, n = 16), with only two lesions showing an SUV below 3. Clinical improvement of primary lesions was seen in all patients; improvement with smaller size and less FDG uptake was visible as early as the second study in 11 patients (69%). Mean SUV values obtained at the second and third studies decreased significantly from those obtained in the first study. In four patients, the disease recurred after breast surgery with high SUV values. The mammograms and sonograms obtained before surgery showed a decrease in the diameter of 6 and 12 primary lesions of the 13 and 14 patients examined, respectively.

CONCLUSION

FDG-PET is valuable for monitoring the effects of preoperative chemotherapy in patients with locally advanced breast cancer with better sensitivity for primary tumor and better specificity for nodal metastasis in comparison with ultrasonography.

Phase II study of docetaxel in patients with epithelial ovarian carcinoma refractory to platinum

We analyzed the efficacy and toxicity of docetaxel in patients with ovarian cancer who failed previous chemotherapy with platinum. Fifty-five patients with measurable ovarian cancer were entered in this Phase II study at The University of Texas M. D. Anderson Cancer Center. Treatment consisted of 100 mg/m2 docetaxel given i.v. every 3 weeks. Because of hypersensitivity reactions, premedication with steroids and antihistamine was initiated during the study. Twenty-two (40%) patients responded (there were 3 complete responders and 19 partial responders). Twenty-one (38%) patients had stable disease. The median survival was 10 months. The main toxicity was neutropenia (98% of patients), with 13 episodes of neutropenic fever. Cumulative fluid retention was the main reason for dose modification and required a combination of diuretics and steroids for palliation. Other side effects were alopecia (100%); anemia (87%); dermatitis (67%); gastrointestinal disorders (53%); stomatitis (49%); neurotoxicity (45%); excessive lacrimation (33%); and hypersensitivity reactions (11%), which in one case were life threatening (loss of consciousness, fluid resuscitation). Docetaxel as a single agent proved to be active in heavily pretreated ovarian cancer patients but is associated with significant side effects. Objective toxicity consisted mainly of neutropenia and fluid retention. Neutropenia was dose limiting and required therapy with granulocyte colony-stimulating factor. Fluid retention was improved but not eliminated by diuretics and corticosteroids. Additional studies of docetaxel in ovarian carcinoma are indicated to define the activity in relation to paclitaxel and in platinum combination therapy.

Phase II study of intravenous topotecan as a 5-day infusion for refractory epithelial ovarian carcinoma

PURPOSE

To determine the efficacy and toxicity of topotecan administered as a 5-day intravenous infusion in patients with advanced ovarian cancer refractory to cisplatin-based chemotherapy.

PATIENTS AND METHODS

Thirty patients with advanced epithelial ovarian cancer refractory to cisplatin-based chemotherapy received intravenous infusions of topotecan 1.5 mg/m2 delivered over 30 minutes each day for 5 days. A course was repeated every 21 days. The patient eligibility requirements included age > or = 18 years, Zubrod score < or = 2, measurable disease, adequate hepatic and renal function, neutrophil count > or = 1,500/microL, platelet count > or = 100,000/microL, and anticipated survival > or = 3 months.

RESULTS

Twenty eight patients were assessable for response and toxicity. All patients were assessable for survival. The major toxicity from administration of topotecan at this dose schedule was myelosuppression; 21 patients required dose reductions. Four patients had neutropenic fever that required hospitalization, and seven patients required platelet transfusions. Maculopapular pruritic exanthema occurred in 20% of patients; gastrointestinal side effects were mild. No deaths were reported on the study. At dose levels of 1.5, 1.25, and 1.0 mg/m2, 61%, 31%, and 25% of patients, respectively, required dose reductions. Of 28 assessable patients, four (14%; 95% confidence interval [CI], 4% to 34%) achieved a partial response (PR) at a median of 1.4 months and lasting 8.9 months, and 17 had stable disease (SD). The overall median survival time was 10.0 months (95% CI, 8.1 to 13.5).

CONCLUSION

Topotecan shows modest clinical activity against cisplatin-refractory ovarian cancer, although the dose-intensity is compromised by the depth of the granulocyte nadir and the duration of granulocytopenia. Further studies of topotecan may necessitate a reevaluation of optimal dose schedule, with the possible incorporation of multilineage cytokines, and its activity in taxane-resistant tumors.

[Organization of the gene for the beta-subunit of human photoreceptor cyclic GMP phosphodiesterase]

Two recombinant bacteriophage lambda clones encoding a 27.8-kb fragment of the human phosphodiesterase beta-subunit gene were isolated from a human genomic library. The nucleotide sequences of 19 exons (from the 4th to 22nd), 18 introns, and the 3'-flanking region were determined. The analysis of the nucleotide sequence of the phosphodiesterase beta-subunit gene revealed four Alu repeats and four minisatellite regions.

Assessment of tumor cell proliferation using [18F]fluorodeoxyadenosine and[18F]fluoroethyluracil

This study was to develop radiofluorinated ethyluracil (FEU) and deoxyadenosine analogues (FAD) for noninvasive assessment of tumor proliferative potential by positron emission tomography (PET). 5-(2-Fluoroethyl)uracil ([18F]FEU) was prepared by treating 2,4-dimethoxy-5-(2-hydroxyethyl)pyrimidine with K18F, followed by hydrolysis with HBr. Fluorodeoxyadenosine ([18F]FAD) was prepared by treating a triacetylated analogue of adenosine with K18F. In vitro cell proliferation assay of [18F]-FEU was performed using human peripheral blood mononucleus cells. Tissue distributions were studied in breast tumor-bearing rats at 0.5, 1, 2 and 4 h along with autoradiography at 45 min postinjection. PET imaging studies were conducted in VX-2 tumor-bearing rabbits. In vitro assay indicated that [18F]FEU incorporated into DNA/RNA during cell proliferation. Tumor-to-tissue count density ratios of [18F]FAD and [18F]-FEU increased as a function of time. [18F]FAD had higher tumor-to-nontumor tissue count density ratios than [18F]FEU. Autoradiograms of [18F]FEU and [18F]FAD, and PET images of [18F]FEU, showed that the tumors could be well visualized. The results suggest that [18F]FEU and [18F]FAD have potential use in evaluating tumor cell proliferation by PET.

Calculation of solvation and binding free energy differences between VX-478 and its analogs by free energy perturbation and AMSOL methods

VX-478 belongs to a novel class of HIV-1 protease inhibitors that are based on N,N-disubstituted benzene sulfonamides. Force field parameters for the N,N-dialkyl benzene sulfonamide moiety have been assembled from the literature and from our own ab initio calculations. These parameters were employed to calculate solvation and binding free energy differences between VX-478 and two analogs. The free energy perturbation method has been used to determine these differences using two approaches. In the first approach, intergroup interaction terms only were included in the calculation of free energies (as in most reports of free energy calculations using AMBER). In the second approach, both the inter- and intragroup interaction terms were included. The results obtained with the two approaches are in excellent agreement with each other and are also in close agreement with the experimental results. The solvation free energies of N,N-dimethyl benzene sulfonamide derivatives (truncated models of the inhibitors), calculated using continuum solvation (AMSOL) methods, are found to be in qualitative agreement with the experimental and free energy perturbation results. The binding and solvation free energy results are discussed in the context of structure-based drug design to show how physicochemical properties (for example aqueous solubilities and bioavailabilities) of these HIV-I protease inhibitors were improved, while maintaining their inhibitory potency.

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.

Use of [18F]fluorodeoxyglucose positron emission tomography in patients with primary malignant brain tumors

In patients with malignant gliomas, [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) may discriminate tumor progression from radionecrosis. We evaluated data from 50 patients undergoing FDG-PET for suspicion of tumor progression. Forty-nine were treated with surgery, 48 with radiotherapy, and 37 with chemotherapy. Twenty-one had intensive radiotherapy with either three daily treatments in two 5-day periods and intravenous carboplatin (17) or interstitial brachytherapy or stereotactic radiotherapy. Twenty underwent surgery after magnetic resonance imaging/FDG-PET; 9 demonstrated increased uptake of FDG and evidence of tumor, whereas 6 had decreased uptake and no evidence of tumor. In 5 patients, there was no correlation (all had intensive radiotherapy). In 17 patients who received bromodeoxyuridine intravenously just before surgery, the bromodeoxyuridine labeling index corresponded to the histological appearance in all but 2 patients (both had received intensive radiotherapy). In 30 patients without surgery, decreased uptake of FDG suggested prolonged survival; increased uptake of FDG did not predict survival. Eight of 10 with intensive radiotherapy had decreased label uptake. We conclude FDG-PET for evaluation of patients with possible recurrent tumors requires more study. In patients with intensive radiotherapy, FDG-PET results cannot be correlated accurately with tumor progression.

Imaging of colorectal carcinoma with technetium-99m radiolabeled Fab' fragments

In this phase III study, patients who had previously undergone surgery for colorectal cancer were studied using a technetium-99m (99mTc)-labeled anti CEA antibody (IMMU-4 [Immunomedics, Morris Plains, NJ] 1mg of protein) to evaluate recurrence. Total-body, planar, and single photon emission computed tomography (SPECT) images were performed within 6 hours of injection. Objectives were to evaluate the efficacy of the 99mTc-labeled anti-CEA antibody, to assess sensitivity and specificity of the agent in known lesions, and to detect occult disease. The impact of antibody study on subsequent surgery was also evaluated. The Fab' fragment has a molecular weight of 54,000 and is supplied as a lyophilized kit that can be instantaneously labeled with 20 to 30 mCi of [99mTc]pertechnetate. In 9 patients with known disease, planar spot imaging identified lesions in 7 (78% sensitivity), SPECT imaging detected lesions in 8 (88% sensitivity), and 1 patient did not have SPECT. In the group of 10 patients with occult (or equivocal) disease, planar imaging sensitivity was 50%, and SPECT sensitivity was 100%. Analysis by site showed 14 of 24 lesions detected by planar imaging (58% sensitivity), and SPECT detected 24 of 24 lesions (100% sensitivity). Tumors as small as .5 cm were visualized in the 19 patients studied. The surgeon judged the antibody study to be impact neutral in 73% of the cases and helpful in 27% of the cases when antibody study altered the presurgical plan.

Evolutionary divergence of pobA, the structural gene encoding p-hydroxybenzoate hydroxylase in an Acinetobacter calcoaceticus strain well-suited for genetic analysis

The pobA gene encoding p-hydroxybenzoate hydroxylase (PobA) from Acinetobacter calcoaceticus has been developed as a genetic tool for the analysis of structure-function relationships in this enzyme. By exploiting the favorable genetic system of A. calcoaceticus strain ADP1, it is possible both to select and to map mutations which disturb PobA activity; characterization and sequence determination of mutants derived in this manner may complement site-directed studies with the homologous Pseudomonas aeruginosa gene. We have determined the nucleotide (nt) sequence of A. calcoaceticus pobA and performed a systematic comparison of the deduced amino acid (aa) sequence with that of the PobA enzyme from Pseudomonas fluorescens, for which the three-dimensional structure is known. Despite a 26% difference in the G+C content of the homologous genes, constraints against structural divergence of the proteins were revealed by an overall identity of 62.4% in the aligned aa sequences of PobA. Clusters of identical sequence occur at previously identified sites of ligand binding and at regions associated with subunit-subunit interaction. Based on the conservation of specific residues involved in flavin binding, we have assembled a consensus sequence for nicotinamide-flavoprotein monooxygenases which differs from that of the oxidoreductase class of flavoproteins. In addition to the conserved regions shared by the two PobA homologs, there are isolated pockets of divergence. The nt sequence divergence in one such region within the A. calcoaceticus gene can be attributed to the acquisition of short nt sequence repetitions.

Synthesis of [18F]fluoroalanine and [18F]fluorotamoxifen for imaging breast tumors

To develop ligands for imaging breast tumors, [18F]fluoro analogue of tamoxifen and [18F]fluoroalanine were radiosynthesized. In vivo biodistribution studies were performed in mammary tumor-bearing rats. In studies on the biodistribution of an [18F]fluoro analogue of tamoxifen, tumor uptake decreased when rats were pretreated with diethylstilbestrol (DES), suggesting that tracer uptake in tumors was receptor-mediated. An estrogen receptor assay indicated that tumors have a receptor density of 7.5 fmol/mg protein. Studies of the distribution of [18F]fluoroalanine in tissue showed that the tumor-to-tissue ratio increases as a function of time. Positron emission tomography (PET) images of tumor-bearing rats demonstrated that tumors can be visualized 1 h after rats are injected with an [18F]fluoro analogue of tamoxifen. PET imaging of pigs after injection of 10 mCi of [18F]fluoro analogue of tamoxifen showed uterine uptake that could be blocked by DES (50 mg). The findings suggest that both radiotracers are useful for imaging breast tumors.

Refinement of the crystal structure of ribonuclease S. Comparison with and between the various ribonuclease A structures

Ribonuclease S (RNase-S) is a complex that consists of two proteolytic fragments of bovine pancreatic ribonuclease A (RNase-A): the S-peptide (residues 1-20) and S-protein (residues 21-124). We have refined the crystal structures of three RNase-S complexes. The first two contain the full-length 20-residue S-peptide and were studied at pHs of 4.75 and 5.5. The third one consists of a truncated form of S-peptide (residues 1-15) and was studied at pH 4.75 as the reference structure for a series of mutant peptide complexes to be reported separately. Excluding residues 16-23 which are either missing (in the S15 complex) or disordered (in both S20 complexes), all three structures refined at 1.6-A resolution are identical within the estimated errors in the coordinates (0.048 A for the backbone atoms). The R-values, residual error, range from 17.4% to 18.6%. The final model of S20, pH 4.75, includes 1 sulfate and 84 water molecules. The side chains of 11 residues were modeled in two discrete conformations. The final structures were independent of the particular RNase-A or RNase-S used as a starting model. An extensive comparison with refined crystal structures of RNase-A reveals that the core of the molecule which is held together with extensive hydrogen bonds is in identical pattern in all cases. However, the loop regions vary from one structure to another and are often characterized by high B-factors. The pattern of thermal parameters appears to be dependent on crystal packing and correlates well with the accessibility calculated in the crystal. Gln60 is a conserved residue in all sequences known to date for this class of ribonucleases. However, it is the only residue that is clearly defined in an unfavorable position (phi = -100 degrees, psi = -130 degrees) on the Ramachandran plot. The origin of the substantial differences between RNase-A and RNase-S in stability to both acid and temperature denaturation and in susceptibility to proteolysis at neutral pH is not obvious in our visual comparison of these two structures.

Multiple myeloma: spinal MR imaging in patients with untreated newly diagnosed disease

Spinal magnetic resonance (MR) imaging was performed in 29 patients with newly diagnosed, untreated multiple myeloma. Nineteen (66%) patients were asymptomatic. Sagittal pre- and postcontrast T1-weighted spin-echo images and gradient-recalled-echo images of the thoracic and lumbosacral spine were obtained. Marrow involvement was identified in 20 (69%) patients. There were three MR patterns: focal lesions in nine patients (31%), diffuse involvement in seven (24%), and an inhomogeneous pattern of tiny lesions on a background of normal marrow in four (14%). A statistically significant correlation between MR imaging patterns of marrow involvement and serum hemoglobin values (one-way, P = .0899; Kruskal-Wallis, P = .0620) and between MR imaging patterns and percentage of marrow plasmacytosis (Kruskal-Wallis, P = .0314) was noted, with patterns of diffuse and focal marrow involvement associated with more abnormal values. Spinal MR imaging in patients with early myeloma may reveal marrow involvement in both symptomatic and asymptomatic patients. Some correlation was found between MR imaging patterns and laboratory indexes of disease.

Evaluation of sensitivity and specificity of upper extremity radionuclide venography in cancer patients with indwelling central venous catheters

Two hundred twenty upper extremity radionuclide venograms were performed using upper extremity injection of 5 mCi of Tc-99m DTPA in each arm of patients with indwelling central lines. Evidence of obstruction was found in 123 patients, collateral flow without anatomic obstruction in six patients, and a slow-flow pattern in 12 patients. Twenty-six of these also underwent upper extremity contrast venography within 48 hours of the scan. Contrast venograms and radionuclide venograms agreed in 19 patients (16 correctly identified as obstructed, three correctly identified as unobstructed). Six patients showed the slow-flow pattern without collaterals or obstruction. Subsequently, six follow-up contrast studies showed no evidence of obstruction or collaterals. The authors conclude that obstruction with collateral flow on radionuclide venograms correctly predicts obstruction. However, the slow-flow pattern does not and should not be used as the sole criterion to diagnose partial obstruction.

SPECT in the evaluation of cancer patients: not quo vadis; rather, ibi fere summus

In the past 7 years, single photon emission computed tomography (SPECT) has evolved from an interesting nuclear medicine technique rarely performed because of technical difficulties into a valuable clinical tool in the management of cancer cases. The development of stable multidetector instruments with collimators and gantries specifically designed for SPECT and the introduction of new radiopharmaceuticals recently approved by the U.S. Food and Drug Administration have rapidly moved SPECT from the field of clinical investigation to clinical practice. SPECT is a valuable addition to other tomographic modalities capable of displaying the physiology of disease as well as anatomy. In this work the authors describe the role of SPECT in a cancer center and, in particular, how they use it to solve clinical problems. They also review the published literature, when appropriate. The authors have found SPECT of particular value in evaluation of myocardial ischemia, in differentiating tumor recurrence from posttherapy changes in the lymphomas, in tumor diagnosis and surveillance, and in separating hemangioma from malignant lesions in the liver.

MR imaging of extracranial nerve sheath tumors

We retrospectively reviewed MR images of 32 histologically proven extracranial nerve sheath tumors (NSTs). There were 23 benign (10 neurofibromas, 13 schwannomas) and 9 malignant NSTs. On T1-weighted images (T1WIs) tumors were isointense or slightly hyperintense to muscle. On T2-weighted images (T2WIs) (11 lesions) and enhanced T1WIs (1 intraspinal lesion), a target pattern with peripheral hyperintense rim and central low intensity was seen in 12 of 23 (52%) benign NSTs (5 of 10 neurofibromas and 7 of 13 schwannomas). This pattern corresponded histologically to peripheral myxomatous tissue and central fibrocollagenous tissue. The pattern was absent in lesions with cystic, hemorrhagic, or necrotic degeneration. These tumors were hyperintense and variably inhomogenous on T2WIs. Malignant NSTs were hyperintense and variably inhomogenous on T2WIs and mimicked benign variably inhomogeneous lesions unless involvement of contiguous structures was visualized. A target pattern was not visible in malignant lesions. Magnetic resonance imaging cannot distinguish schwannomas from neurofibromas, and benign tumors may mimic malignant NSTs when cystic, hemorrhagic, and necrotic degeneration is present. A target pattern may be visualized in some benign NSTs, and evaluation of this sign with assessment of location and growth along nerves may help to avoid confusion with other lesions.

Differentiation of residual or recurrent tumors from post-treatment changes with F-18 FDG PET

Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) was used to differentiate recurrent or residual malignant disease from the effects of cancer treatment. Transaxial images were obtained after injection of 5-10 mCi (185-370 MBq) of F-18 FDG in 68 patients (including 33 with brain tumors) whose posttreatment computed tomographic (CT) or magnetic resonance (MR) imaging findings had been suggestive of malignant disease. PET findings were correlated with surgical results in 18 patients and with the outcomes of CT, MR imaging, clinical, and laboratory 9-month follow-up studies in 50 patients. There was good agreement between F-18 FDG uptake and presence or absence of malignant disease except in four cases of brain tumors in which histologic findings could not be correlated with biologic behavior. The putative sensitivity and specificity in the 33 cases of brain tumors were 80% and 94%, respectively. The authors conclude that PET with F-18 FDG is useful in detection of previously treated metabolically active tumors but is limited in diagnosis of recurrent microscopic or metabolically inactive tumors.

Mutation of a single amino acid converts germ cell alkaline phosphatase to placental alkaline phosphatase

Human placental and germ cell alkaline phosphatases (PLAP and GCAP, respectively), are characterized by their differential sensitivities to inhibition by L-leucine, EDTA, and heat. Yet, they differ by only 7 amino acids at positions 15, 67, 68, 84, 241, 254, and 429 within their respective 484 residues. To determine the structural basis and the amino acid(s) involved in these physicochemical differences, we constructed three GCAP mutants by site-directed mutagenesis and six GCAP/PLAP chimeras and then expressed these alkaline phosphatase mutants in COS-1 cells. We report that the differential reactivity of PLAP and GCAP depends critically on a single amino acid at position 429. GCAP with Gly-429 is strongly inhibited by L-leucine, EDTA, and heat, whereas PLAP with Glu-429 is resistant. By substituting Gly-429 of GCAP with a series of amino acids, we demonstrate that the relative sensitivities of these mutants to L-leucine, EDTA, and heat inhibition are, in general, parallel. Mutants in the order of resistance to these treatments are: Glu (most resistant), Asp/Ile/Leu, Gln/Val/Lys, Ser/His, and Arg/Thr/Met/Cys/Phe/Trp/Tyr/Pro/Asn/Ala/Gly (least resistant). However, the Ser-429 and His-429 mutants were more resistant to EDTA and heat inhibition than the wild-type GCAP, but were equally sensitive to L-leucine inhibition. Structural analysis of mammalian alkaline phosphatase modeled on the refined crystal structure of Escherichia coli alkaline phosphatase indicates that the negative charge of Glu-429 of PLAP, which simultaneously stabilizes the protein as a whole and the metal binding specifically, probably acts through interactions with the metal ligand His-320 (His-331 in E. coli alkaline phosphatase). Replacement of codon 429 with Gly in GCAP leads to destabilization and loosening of the metal binding. The data suggest that the natural binding site for L-leucine may be near position 429, with the amino and carboxyl groups of L-leucine interacting with bound phosphate and His-432 (His-412 in E. coli alkaline phosphatase), respectively.

Soft-tissue sarcoma: MR imaging vs sonography for detection of local recurrence after surgery

To determine the value of MR and sonography in detecting local recurrences of soft-tissue sarcomas after surgery, 26 MR and sonographic studies performed in 21 patients were reviewed retrospectively. Recurrences were confirmed histologically in 12 (46%) of 26 studies. The MR images and sonograms were obtained within 1 month of each other. The findings were classified as recurrence, no recurrence, or indeterminate. Sonography was instrumental in guiding fine-needle aspiration biopsy of impalpable lesions. In two cases, the findings on sonography were indeterminate. In both of these cases, the sonograms had been obtained soon after surgery (at 2 and 4 months). The sensitivity and specificity in the detection of local recurrences were 83% and 93%, respectively, for MR and 100% and 79%, respectively, for sonography. These differences were not statistically significant. We conclude that MR and sonography appear to be equally useful in the detection of local recurrences of soft-tissue sarcomas, sonography can be used for routine follow-up and in guiding needle biopsies, sonography may be more difficult to interpret than MR during the early postoperative period, and MR should be used if sonography is inconclusive.

Case report 682. Neuroepithelioma of soft tissues of the knee

Peripheral neuroepitheliomas should be included in the differential diagnosis of a soft-tissue tumor in the extremities or chest wall, especially in young adolescents. MRI provides useful information as to the extent of the tumor and relationship with adjacent structures, although it may not differentiate neuroepitheliomas from other, more common, soft-tissue sarcomas. Together with clinical and histological findings, MRI can assist in the diagnosis and treatment planning of this tumor.

MR appearance of the distended iliopsoas bursa

The purpose of this essay is to illustrate the MR appearance of the distended iliopsoas bursa. The bursa must be recognized on MR scans to avoid confusing it with malignant neoplasms and other lesions.