Comparison of MRI pulse sequences in defining prostate volume after permanent implantation.

PURPOSE: To determine the relative value of three MRI pulse sequences in defining the prostate volume after permanent implantation. METHODS AND MATERIALS: A total of 45 patients who received a permanent 125I implant were studied. Two weeks after implantation, an axial CT scan (2 mm thickness) and T1-weighted, T1-weighted fat saturation, and T2-weighted axial MRI (3-mm) studies were obtained. The prostate volumes were compared with the initial ultrasound planning volumes, and subsequently the CT, T1-weighted, and T1-weighted fat saturation MRI volumes were compared with the T2-weighted volumes. Discrepancies in volume were evaluated by visual inspection of the registered axial images and the registration of axial volumes on the sagittal T2-weighted volumes. In a limited set of patients, pre- and postimplant CT and T2-weighted MRI studies were available for comparison to determine whether prostate volume changes after implant were dependent on the imaging modality. RESULTS: T1-weighted and T1-weighted fat saturation MRI and CT prostate volumes were consistently larger than the T2-weighted MRI prostate volumes, with a volume on average 1.33 (SD 0.24) times the T2-weighted volume. This discrepancy was due to the superiority of T2-weighted MRI for prostate definition at the following critical interfaces: membranous urethra, apex, and anterior base-bladder and posterior base-seminal vesicle interfaces. The differences in prostate definition in the anterior base region suggest that the commonly reported underdose may be due to overestimation of the prostate in this region by CT. The consistent difference in volumes suggests that the degree of swelling observed after implantation is in part a function of the imaging modality. In patients with pre- and postimplant CT and T2-weighted MRI images, swelling on the T2-weighted images was 1.1 times baseline and on CT was 1.3 times baseline, confirming the imaging modality dependence of prostate swelling. CONCLUSION: Postimplant T2-weighted MRI images provided superior prostate definition in all critical regions of the prostate compared with CT and the other MRI sequences tested. In addition to defining an optimal technique, these findings call two prior observations into question. Under dosing at the anterior base region may be overestimated because of poor definition of the prostate-bladder muscle interface. The swelling observed after implantation was lower on T2-weighted images as well, suggesting that a fraction of postimplant swelling is a function of the imaging modality. These findings have implications for preimplant planning and postimplant evaluation. As implant planning techniques become more conformal, and registration methods become more efficient, T2-weighted MRI after implantation will improve the accuracy of postimplant dosimetry.

Compensation of x-ray beam penumbra in conformal radiotherapy.

In radiotherapy, the gross tumor volume is surrounded by a clinically defined margin to allow for the presence of undetected malignant cells. Additional margins are added to accommodate positioning uncertainties and organ motion, creating a planning target volume, or PTV. Finally, a margin is included in the beam apertures surrounding the PTV to account for the dose fall-off at the beam edges (i.e., the "penumbra"). For higher energy beams and for low density tissues adjacent to the PTV, the beam aperture margin should be increased to account for the increased range of scattered photons and electrons. However, increased margins also increase the volume of normal tissue irradiated. In this work, the beam aperture margin is reduced by using filters and multileaf collimator (MLC) techniques to create compensating rinds of increased beam intensity. These compensation techniques were evaluated for 6 and 18 MV x rays by calculating penumbral widths as a function of the increased beam intensity in the rind, the rind width, and tissue density. Dose calculations were performed using a 3D superposition algorithm, which includes an extrafocal source model. Calculations were validated experimentally with film dosimetry. Results show the distance between the 95%-50% isodose lines is reduced from 11 mm to 4 mm for 6 MV x rays in the lung phantom, when the beam intensity is increased by 20% in a 10 mm wide rind. At 18 MV, this distance is reduced from 16 mm to 6 mm with a 20% increase in rind intensity, but a 15 mm wide rind is required. In all cases, penumbra compensation did not result in any appreciable increase in scatter dose outside the field boundaries. These results suggest that penumbra compensation is a practical means of controlling the beam aperture margin.

Monitor unit settings for intensity modulated beams delivered using a step-and-shoot approach.

Two linear accelerators have been commissioned for delivering IMRT treatments using a step-and-shoot approach. To assess beam startup stability for 6 and 18 MV x-ray beams, dose delivered per monitor unit (MU), beam flatness, and beam symmetry were measured as a function of the total number of MU delivered at a clinical dose rate of 400 MU per minute. Relative to a 100 MU exposure, the dose delivered per MU by both linear accelerators was found to be within +/-2% for exposures larger than 4 MU. Beam flatness and symmetry also met accepted quality assurance standards for a minimum exposure of 4 MU. We have found that the performance of the two machines under study is well suited to the delivery of step-and-shoot IMRT. A system of dose calculation has also been commissioned for applying head scatter corrections to fields as small as 1x1 cm2. The accuracy and precision of the relative output calculations in water was validated for small fields and fields offset from the axis of collimator rotation. For both 6 and 18 MV x-ray beams, the dose per MU calculated in a water phantom agrees with measured data to within 1% on average, with a maximum deviation of 2.5%. The largest output factor discrepancies were seen when the actual radiation field size deviated from the set field size. The measured output in water can vary by as much 16% for 1x1 cm2 fields, when the measured field size deviates from the set field size by 2 mm. For a 1 mm deviation, this discrepancy was reduced to 8%. Steps should be taken to ensure collimator precision is tightly controlled when using such small fields. If this is not possible, very small fields should not contribute to a significant portion of the treatment, or uncertainties in the collimator position may effect the accuracy of the dose delivered.

Reveal for Salmonella test system.

The Reveal for Salmonella (RSS) test system is a presumptive qualitative test that detects the presence of Salmonella organisms in foods within 21 h total testing time, allowing the user to release negative products 24 h earlier than when using other rapid test kits. Foods are enriched with a proprietary resuscitation medium called Revive and then selectively enriched with either Selenite Cystine or Rappaport-Vassiliadis selective media. The enriched culture is used to inoculate the RSS detection device, which initiates a lateral flow through a reagent zone containing anti-Salmonella antibodies conjugated to colloidal gold particles that capture antigens present in the culture. The antigen-antibody complex migrates farther and is captured by an additional anti-Salmonella antibody, causing the colloidal gold to precipitate and form a visual line, indicating a positive result. A procedural control line also will form regardless of the presence of Salmonella organisms to indicate the test is working properly. Existing AOAC Official Methods for Salmonella organisms require a 48 h enrichment before testing. Hence, a food product has to be held before release, adding extra cost to the company and the consumer. The RSS test system was evaluated by quantitative spiking studies. Although AOAC encourages inclusion of naturally contaminated foods, almost all microbiological AOAC validation studies have been performed with artificially contaminated foods for absolute control over the study. The RSS test system is designed to test many food types for Salmonella organisms and has a limit of detection of 5-10 colony-forming units (cfu)/25 g with a false-negative rate of < 1% and a false-positive rate of < 5.0%. It showed an 81% overall agreement with the traditional procedure of the U.S. Department of Agriculture's Food Safety Inspection Service.

Fumonisins Veratox. A new rapid quantitative ELISA for determination of fumonisin in food and feed.

Polyclonal antibodies against fumonisin B1 were produced by immunizing sheep with fumonisin B1-keyhole limpet hemocyanin as an immunogen. A quantitative competitive enzyme-linked immunosorbent assay was developed whereby free fumonisins or sample extract containing fumonisins and enzyme-labelled fumonisin competed for binding to the solid phase-bound antibodies. The color intensity of wells, formed by substrate reaction with the enzyme, was inversely related to FB1 concentration. Detection limits for the assay were 0.1 ng/mL fumonisin B1 and concentrations of fumonisins B1, B2, and B3 required for 50% binding inhibition were 5.5, 23 and 18 ng/mL, respectively. For food and feed analyses, samples were extracted with 70% methanol and dilution of the extracts were used directly for ELISA. ELISA results were compared to HPLC analyses by a reference laboratory and the correlation (r value) between ELISA and HPLC was 0.967. The assay may be used to quantitate fumonisins in food and feed within 30 minutes.

Evaluation of the micronucleus test in vitro using Chinese hamster cells: results of four chemicals weakly positive in the in vivo micronucleus test.

A rapid and simple procedure for the micronucleus test (MNT) in vitro using Chinese hamster ovary (CHO) cells was established in our laboratory. The assay is intended to quickly screen chromosomal aberrations in vitro within the framework of industrial genotoxicity studies. To test the sensitivity of the assay in the experiments described here, four substances, classified as noncarcinogens but reported as weak inducers of micronuclei (MN) in bone-marrow cells of mice, were evaluated in the MNT in vitro. Of the four compounds, ascorbic acid, phenol, and 2,6-diaminotoluene proved to be genotoxic in the MNT in vitro. Titanium dioxide, which could not be dissolved in the culture medium, did not induce MN. The MNT in vitro proved to be quick and relatively simple and to yield highly reproducible results when testing the four chemicals.

Diagnostic value of C-reactive protein in acute appendicitis.

Serum C-reactive protein was measured in 56 patients hospitalized with a suspected diagnosis of acute appendicitis. Based on these determinations, four groups of patients were defined: Group A = 26 patients with acute appendicitis who had a C-reactive protein level higher than 2.5 mg/dl. Group B = 4 patients with a C-reactive protein level lower than 2.5 mg/dl who, after surgery based on a presumed diagnosis of acute appendicitis, were found to have a normal appendix. Group C = 22 patients with nonspecific abdominal pain, 18 (72 percent) of whom had an elevated C-reactive protein level, although in only 4 (7.1 percent) were these levels higher than 2.5 percent mg/dl. Group D = 4 patients who had diseases other than acute appendicitis. It is concluded that an increase in C-reactive protein levels to more than 2.5 mg/dl is not a definite indicator of acute appendicitis. However, if the C-reactive protein level in blood drawn 12 hours after the onset of symptoms is less than 2.5 mg/dl, acute appendicitis can be excluded.

Factors influencing the DNA content of radiation-induced micronuclei.

The distribution of the DNA content of radiation-induced micronuclei was analysed in several cell lines (Chinese hamster, Syrian hamster and mouse NIH-3T3 cells) by flow cytometry. Frequency and DNA content of micronuclei were measured simultaneously using fluorescence and forward scatter signals of micronuclei and nuclei in suspension stained with ethidium bromide. Computerized random breakage of chromosomes and random combination of fragments was performed to compare the measured micronucleus distributions in synchronized cells irradiated during G1-phase with calculated distributions. The measured DNA distribution of radiation-induced micronuclei was found to be influenced by several factors: (1) the DNA distribution and the centromeric index of the chromosomes in the various cell lines; (2) the cell cycle phase at time of micronucleus measurement due to DNA synthesis in micronuclei; (3) the presence of chromosome fragments in micronuclei; and (4) the presence of whole chromosomes in micronuclei. These factors were shown to be responsible for the previously found large radiation-induced micronuclei which could not be explained by the classic assumption only that radiation-induced micronuclei are mainly produced by single acentric fragments.

Analysis of radiation-induced micronuclei by fluorescence in situ hybridization (FISH) simultaneously using telomeric and centromeric DNA probes.

Fluorescence in situ hybridization using simultaneously a combination of DNA probes for the telomeric hexamer repeat (TTAGGG) and the centromerically repeated murine gamma-satellite DNA was applied to analyze the nature of radiation-induced micronuclei in mouse NIH 3T3 fibroblasts. After subtraction of spontaneously occurring micronuclei independent from the dose and time after irradiation, approximately 22% of the radiation-induced micronuclei did not reveal any hybridization signal. Approximately 17% showed one centromeric hybridization signal and about four telomeric signals, suggesting their origin from whole chromosomes. Almost 60% of radiation-induced micronuclei had telomeric signals only, suggesting their origin from acentric fragments. A fraction of micronuclei were found to contain two or more acentric fragments. Micronuclei derived from whole chromosomes or from multiple acentric fragments might, together with DNA synthesis in micronuclei, explain the occurrence of radiation-induced micronuclei with DNA contents greater than the largest chromosome arm.

Classification of micronuclei in murine erythrocytes: immunofluorescent staining using CREST antibodies compared to in situ hybridization with biotinylated gamma satellite DNA.

Micronuclei (MN) in erythrocytes of mouse bone marrow cells were induced in vivo by the spindle poisons colchicine (COL) and vinblastine (VBL), by hydroquinone (HQ) and by the alkylating agent mitomycin C (MMC). Two different methods were applied to detect whole chromosomes with centromeric proteins or chromatin in MN to discriminate between spindle damaging or clastogenic activity of these chemicals. One method determined the fraction of MN with centromeric chromatin by immunofluorescent staining using antikinetochore antibodies (CREST staining). The other method applied non-radioactive in situ hybridization with a novel DNA probe. The fractions of MN that showed positive signals by either technique thus indicating with a high probability the presence of whole chromosomes instead of acentric fragments, were in good agreement for COL, VBL and HQ. After application of MMC, however, 4.5% of the MN were CREST-positive, while 29% gave a positive hybridization signal. The results suggest, that kinetochores may have lost certain centromeric antigens due to treatment with MMC so that MN containing whole chromosomes appear CREST-negative. The presented in situ hybridization scheme using satellite DNA is a more direct detection and is advantageous to the CREST staining technique in that it is unaffected by damage of kinetochore or centromeric function.

Application of the murine anti-Gd-2 antibody 14.Gd-2a for diagnosis and therapy of neuroblastoma.

We have tested the sialoganglioside monoclonal antibody Gd-2a for scintigraphic diagnostic and for immunotherapy in children with neuroblastoma stage IV. We could confirm tumor sites with Gd-2a scans in 1/2 children. Doses of 20-60 mg/m2 were administered daily for 5-10 days. 2/2 children with multiple tumor sites showed significant tumor regression. Four children, treated preventively, are still in clinical remission. One child showed tumor progression despite Gd-2a treatment. Adverse effects included itching, rashes, and pain.

Neonatal duodenal perforation.

Duodenal perforation in neonates is uncommon, and has been described rarely in the third part of the duodenum. Gastrointestinal perforations without an obvious cause have been labeled as "spontaneous." We report a case of perforation in the third part of the duodenum in a premature infant for which there was no obvious cause. In such "spontaneous" perforations, multifactorial etiology is likely and possible factors are discussed. The high mortality rate in such patients can be improved by early diagnosis and prompt resuscitation followed by surgery. Peritoneocentesis plays an important diagnostic role. It is also therapeutic in relieving the respiratory distress caused by free intraperitoneal air. The majority of duodenal perforations are amenable to primary closure at surgery and this should be the treatment of choice.

Application of antikinetochore antibody staining (CREST staining) to micronuclei in erythrocytes induced in vivo.

Micronuclei (MN) can be formed by acentric chromosome fragments or whole lagging chromosomes. In order to discriminate MN produced by chromosome breakage from those arising from spindle malfunction a staining method using immunofluorescent kinetochore antibodies has been applied successfully in vitro. In the present study MN in polychromatic erythrocytes of mouse bone marrow cells induced in vivo by the spindle poison colchicine (COL) and the clastogen mitomycin C (MMC) were analysed after CREST staining. The staining method was modified by using pretreatment with detergents in order to allow a good penetration of the antibodies into the MN. About 66% of the MN induced by COL in contrast to only 4.5% of the MMC induced MN were CREST-positive. The preliminary results show that the CREST staining is also in MN induced in vivo capable of detecting the origin of MN and to discriminate between the spindle damaging or clastogenic activity of environmental agents. The method described will give supplementary information about MN, it cannot substitute for the common micronucleus test.

Suspect spindle poisons: analysis of c-mitotic effects in mouse bone marrow cells.

In the coordinated programme to study aneuploidy induction, sponsored by the Commission of the European Communities, 10 known or suspect spindle poisons (colchicine, econazole, chloralhydrate, hydroquinone, diazepam, thiabendazole, cadmium chloride, pyrimethamine, vincristine and thimerosal) were tested in mouse bone marrow cells for the induction of c-mitotic effects. Three criteria were chosen: changes of the mitotic index, induction of chromatid contraction and spreading and decrease of anaphase frequencies. Among the chemicals tested colchicine, econazole, chloralhydrate, hydroquinone and vincristine were found positive. Diazepam, thiabendazole, cadmium chloride, pyrimethamine and thimerosal revealed no induction of c-mitotic effects under the conditions tested. Mitotic block and subsequent chromosome malsegregation (non-disjunction) are related phenomena. The three criteria chosen are considered as an indicative pre-screening test for the aneuploidy inducing potency of a chemical in mitotic, but not in meiotic cells. The present experiments were also regarded as a dose-finding exercise for further in vivo studies.

Failure of somatostatin or an analog to promote closure of end pancreatic fistulae.

Somatostatin has been reported to promote closure of pancreatic fistulae, but use of the analog SMS 201-995 (Sandoz, Inc.) has not previously been published. We used this analog to treat two patients with end pancreatic fistulae refractory to conventional therapy. One patient had disruption of a pancreaticojejunostomy after pancreaticoduodenectomy and the other had acute necrotizing gallstone pancreatitis and disruption of the pancreatic duct in the tail. SMS 201-995 (100-150 micrograms/d) abruptly decreased fistula output by 50% in both patients but further increases in dosage had no further effect on output. Neither fistula healed after 3-4 wk of therapy. Treatment with somatostatin or its analogs alone will not lead to closure of a pancreatic fistula complicated by factors such as distal obstruction, infection, or foreign body. Somatostatin may promote closure of lateral fistulae and may simplify the management of patients with high output fistulae.

Intrapancreatic communication of bile and pancreatic ducts secondary to pancreatic necrosis.

An unusual complication of acute necrotizing pancreatitis occurred in which erosion of the intrapancreatic common bile duct and cephalic pancreatic duct formed a pancreaticobiliary cavity. This pancreatic process was observed to enhance during contrast computed tomography and was hypervascular during angiography, making preoperative diagnosis difficult. To our knowledge, the spontaneous development of such a cavity as a complication of acute pancreatitis has not been reported. The patient was successfully treated with pancreaticoduodenectomy.

Surgical versus endoscopic management of common bile duct stones.

The charts of all patients with common bile duct (CBD) stones admitted to Virginia Mason Medical Center between January 1, 1981 and July 31, 1986 were reviewed to define current methods of management and results of operative versus endoscopic therapy. Two hundred thirty-seven patients with CBD stones were treated. One hundred thirty patients had intact gallbladders. Of these patients, 76 (59%) underwent cholecystectomy and common bile duct exploration (CBDE) while 54 (41%) underwent endoscopic papillotomy (EP) only. Of the 107 patients admitted with recurrent stones after cholecystectomy, all but five were treated with EP. The overall mortality rate was 3.0%. Complications, success, and death rates were all similar for CBDE and EP, but the complications of EP were often serious and directly related to the procedure (GI hemorrhage, 6; duodenal perforation, 5; biliary sepsis, 4; pancreatitis, 1). Patients undergoing EP required significantly shorter hospitalization than those undergoing CBDE. Multivariate analysis showed that age greater than 70 years, technical failure, and complications increased the risk of death, regardless of procedure performed. Twenty-one per cent of those undergoing EP with gallbladders intact eventually required cholecystectomy. The conclusion is that the results of EP and CBDE are similar, and the use of EP has not reduced the mortality rates of this disease.