A three-dimensional finite element model and image reconstruction algorithm for time-domain fluorescence imaging in highly scattering media.

In this work, development and evaluation of a three-dimensional (3D) finite element model (FEM) based on the diffusion approximation of time-domain (TD) near-infrared fluorescence light transport in biological tissue is presented. This model allows both excitation and fluorescence temporal point-spread function (TPSF) data to be generated for heterogeneous scattering and absorbing media of arbitrary geometry. The TD FEM is evaluated via comparisons with analytical and Monte Carlo (MC) calculations and is shown to provide a quantitative accuracy which has less than 0.72% error in intensity and less than 37 ps error for mean time. The use of the Born-Ratio normalized data is demonstrated to reduce data mismatch between MC and FEM to less than 0.22% for intensity and less than 22 ps in mean time. An image reconstruction framework, based on a 3D FEM formulation, is outlined and simulation results based on a heterogeneous mouse model with a source of fluorescence in the pancreas is presented. It is shown that using early photons (i.e. the photons detected within the first 200 ps of the TPSF) improves the spatial resolution compared to using continuous-wave signals. It is also demonstrated, as expected, that the utilization of two time gates (early and latest photons) can improve the accuracy both in terms of spatial resolution and recovered contrast.

Improvement of transperineal implant dosimetry by intraoperative cystoscopic confirmation of prostate anatomy.

PURPOSE: A simple, inexpensive method to aid in the accurate placement of permanent seeds for prostate brachytherapy is described. The effect of identifying the prostate base and apex cystoscopically relative to registration seeds placed at the beginning of the implant is discussed. MATERIALS AND METHODS: At the beginning of each implant procedure a pair of marker seeds are first placed in the prostate, including 1 seed at the base and 1 at the apex. Using a cystoscope, the urologist identifies the prostatic base and apex, and a fluoroscopic record is obtained. The positions of the base and apex relative to the marker seeds are monitored throughout the case via fluoroscopy to aid in needle and seed placement for the implant. RESULTS: Use of this method significantly improved coverage of the prostate apex, reduced overall dose variance in the prostate base and improved overall gland dosimetry by 22% as measured by the D90 quality metric (minimal dose which covers 90% of the prostate volume). CONCLUSIONS: While the clinical efficacy of improved target coverage on local control and survival awaits further clinical investigation, we encourage others to adopt this easy technique to ensure better, more consistent interstitial implants.

Sarcoidosis manifesting as acute appendicitis: report of a case.

PURPOSE: This report presents a patient who developed signs and symptoms of acute appendicitis because of sarcoid involvement of the appendix. METHODS: This is a retrospective case review with review of the English language literature. RESULTS: The patient underwent appendectomy for suspected acute appendicitis. Histologically the appendix had no signs of acute inflammation but did have noncaseating granulomas. The patient's abdominal pain resolved following appendectomy, and she has had no further similar pain in the two years since the operation. CONCLUSION: Patients with sarcoidosis may develop signs and symptoms of acute appendicitis without inflammation. Operative exploration should not be delayed in equivocal cases of right lower quadrant abdominal pain in patients with sarcoidosis.

Age dependent changes in serotonin and dopamine receptors in Aplysia californica.

Age related changes in dopaminergic and serotonergic receptors were examined in Aplysia californica. In this study dopamine (DA) and serotonin (5-HT) receptor levels were examined for animals belonging to 4-, 5-, 6-, 8-, 9- and 12-month age groups. Receptors analysis was performed using radio-labeled d-[3H] lysergic acid diethylamide (LSD) as the specific ligand. Specific binding for 5-HT was found to be significantly greater than that for DA in the young (4-month post-hatch) animals. The total DA and 5-HT receptor levels changed significantly with age. Dopamine levels increased from 5.34 fmol/mg of protein at 4 months to 19.11 fmol/mg at 12 months. Serotonin receptor levels increased from 7.35 fmol/mg at 4 months to 20.45 at 12 months.

MR susceptometry: an external-phantom method for measuring bulk susceptibility from field-echo phase reconstruction maps.

A novel method for estimating the susceptibility of an object by using the magnetic resonance (MR) imaging field distortions in an external-reference water bath next to the object is described. The field measurement was obtained with a phase reconstruction from a gradient-echo acquisition. A field model of an arbitrary object in a static magnetic field was discretely calculated from geometry determined from the magnitude reconstruction. Least-squares estimation yields the susceptibility of the object. Required (and proven) assumptions include validity of superposition, object homogeneity, negligible higher-order field terms, field-model accuracy, geometric-model accuracy, and correlation of gradient-echo phase to field distortion. MR susceptometry estimation of phantoms yielded susceptibility estimates that correlated well with known values (r > .9975). This MR susceptometry method is a first step toward quantitation of iron levels through MR imaging phase information in patients with iron overload.

Elective colostomy closure in an AIDS patient.

This article describes a 27-year-old patient with acquired immunodeficiency syndrome (AIDS) who underwent emergency sigmoid colostomy, Hartmann's pouch, and presacral drainage for rectal perforation. Three months later, he underwent uneventful elective colostomy closure, a procedure previously unreported in an AIDS patient. He remained without gastrointestinal symptoms for 14 months after colostomy closure until he died from central nervous system toxoplasmosis. A diagnosis of AIDS alone should not preclude colostomy closure in AIDS patients.

Estimation of Bloch model MT spin system parameters from Z-spectral data.

Previous studies have described magnetization transfer (MT) Z-spectra in terms of a two-pool Bloch model, with six spin-system parameters KA, F, T1A, T1B, T2A, and T2B. By simulation, we show that a process including nonlinear constrained optimization can be used to accurately and uniquely estimate spin-system parameters from MT Z-spectra prepared by continuous wave (CW) RF irradiation. Experiments producing Z-spectra by pulsed RF irradiation give substantially different magnetization values, relative to MT acquisitions obtained by CW RF irradiation, at small offset frequencies, with a consequence that only T2B can be uniquely determined. However, several equalities and bounds involving four of the other parameters (KA, F, T1A, and T1B) are derived, which are applicable to pulsed data. These relationships allow calculation of "free pool" magnetization corresponding to complete saturation of the restricted pool, without requiring that this complete saturation be experimentally achieved. MT experimental data from pulsed RF irradiation on boiled egg albumin, obtained using a clinical whole-body MRI system, are analyzed using an optimization algorithm and the derived expressions.

Identifying the low-risk patient with penetrating colonic injury for selective use of primary repair.

As the mortality rate for penetrating colonic injuries approaches zero, emphasis has shifted toward reducing associated morbidity. This study was done to identify patients at low risk for colon-related extensive morbidity after primary repair of a penetrating colonic injury. The records of 100 consecutive patients admitted to the District of Columbia General Hospital (DCGH) between 1984 to 1990, surviving more than 24 hours after full-thickness penetrating colonic injuries, were retrospectively reviewed. Data collection included mechanism, management and anatomic location of the colonic injury. Severity of injury was evaluated by the Trauma Score (TS), Penetrating Abdominal Trauma Index (PATI), Flint Colon Injury Score (FCIS), time in the operating room, blood transfused during the first 24 hours and presence of preoperative shock (systolic blood pressure less than 90 millimeters of mercury). Mechanism of injury included 97 gunshot wounds and three stab wounds. Fifty-seven patients had primary repair (17 having resection and anastomosis) and 43 had colostomy. The anatomic location of injury was right colon in 37, transverse colon in 27, left colon in 35 and multiple sites (two) in one patient. In this series, only two patients had colon-related extensive morbidity--a parastomal hernia and wound dehiscence, both requiring operative intervention. There were no instances of intraperitoneal abscess formation. One patient died from overwhelming pneumonia after segmental resection of the colon with primary anastomosis. The literature reports a 12 to 42 percent colon-related morbidity rate in patients sustaining penetrating colonic injuries. This series from DCGH represents the lowest colon-related extensive morbidity and mortality rates reported to date in any substantial series of penetrating abdominal trauma. We attribute the 2 percent extensive morbidity rate to high TS (mean of 15.7), low PATI (mean of 24.2), low FCIS (mean of 1.9) and few associated intra-abdominal injuries (59 percent of patients with less than two). We have identified a group of patients with full-thickness penetrating injuries to the colon, few associated intra-abdominal injuries, high TS, low PATI and low FCIS who can be managed safely and judiciously by primary repair without undue morbidity and mortality.

Intraoperative high-dose rate interstitial irradiation of hepatic metastases from colorectal carcinoma. Results of a phase I-II trial.

BACKGROUND: Resection of liver metastases from colorectal carcinoma can be curative. Unresectable but liver-confined metastases might be ablated by high-dose radiation with a similar curative result. METHODS: At Georgetown University Hospital, 22 patients with unresectable hepatic metastases from colorectal carcinoma underwent 24 interstitial irradiation procedures at laparotomy in a Phase I-II study. A single dose was administered with a high-dose rate iridium-192 afterloader. Dose to the tumor periphery was 20 Gy, 25 Gy, and 30 Gy in 13, 9, and 2 procedures, respectively. RESULTS: No acute or chronic radiation toxicity has occurred at a median follow-up of 11 months. Median actuarial local control at irradiated sites was 8 months, with 26% actuarial local control at 26 months by computed tomography (CT) or magnetic resonance imaging (MRI) scanning. In the two patients undergoing two procedures each, a second biopsy of previously irradiated areas demonstrated tumor eradication. CONCLUSIONS: This innovative, radical approach to unresectable colorectal hepatic metastases proved safe. Additional study is needed to determine whether interstitial irradiation is as effective as surgical resection, or whether it alters the natural history of the disease or longevity.

Recurrent bronchogenic cyst. An argument for complete surgical excision.

A case of a recurrent bronchogenic cyst in a 42-year-old woman 25 years after original resection led to a review of the therapeutic modalities for the management of bronchogenic cysts. Recurrence of bronchogenic cysts is a reason for complete surgical excision of symptomatic bronchogenic cysts at initial presentation. If either asymptomatic or symptomatic bronchogenic cysts are drained or partially excised, long-term follow-up is indicated to detect recurrence.

Treatment of bleeding stomal varices. Report of a case and review of the literature.

Variceal bleeding from ileostomy, colostomy, or ileal conduit stomas is unusual. There is no consensus on which of the various treatment options is best. A case of bleeding ileostomy varices is presented. The English-language medical literature since 1962 is reviewed and an additional 71 cases of stomal variceal bleeding are identified. Treatment options evaluated include stomal manipulation, variceal ligation, sclerotherapy, beta blockade, and surgical shunting. The incidence of rebleeding, requirement for additional procedures, and survival with the various options are compared. Although stomal manipulation was the most commonly performed procedure, portosystemic shunting had the lowest incidence of both rebleeding and need for additional procedures (4 percent each) and provided the longest mean postoperative survival (50 months). The authors conclude that portosystemic shunting is the treatment of choice in patients with bleeding from stomal varices who are good surgical candidates.

Venobronchial fistula: a complication associated with central venous catheterization for chemotherapy.

We report a case in which a venobronchial fistula developed 4 months after insertion of a silicone rubber chronic central venous catheter for chemotherapy administration. In retrospect, the tip of the catheter was in the azygous vein rather than in the superior vena cava. The suboptimal position of the catheter tip, in combination with the infusion of sclerosing chemotherapeutic agents and hyperalimentation solution, may have predisposed the patient to this complication. Accurate localization of the tip of central venous catheters at the time of placement should minimize catheter-related complications, including the rare complication of venobronchial fistula. After placement of chronic central venous catheters, biplanar chest X-rays should be obtained to determine catheter tip location prior to the instillation of chemotherapeutic agents. Any residual questions concerning the catheter tip location after biplanar X-rays should be addressed by prompt venography through the catheter.

Effects of different data base formats on information retrieval.

This research examined the effects of three different data base formats on the information retrieval performance of users. Spatial, tabular, and verbal forms of two data base domains (airline and thesaurus) were constructed, along with questions that required users to search through the data base to determine the correct response. Three types of questions, compatible with the forms of the data bases, were designed--spatial, tabular, and verbal. The data indicate that users' responses to the questions are faster and more accurate when the format of the information in the data base matches the type of information needed to answer the question. Although the importance of matching data base format to query type may seem obvious, it would appear that the designers of most current data base systems have not taken this into account.

Perforation complicating rifampin-associated pseudomembranous enteritis.

An 18-year-old man developed a perforated jejunum while receiving rifampin antituberculous chemotherapy. The perforations were located within longitudinal ulcers characteristic of pseudomembranous enterocolitis. Pseudomembranous inflammation was limited to the small intestine. The absence of colonic involvement delayed establishment of the diagnosis. Successful surgical intervention consisting of small-bowel resection with primary anastomosis was accomplished for this rare and potentially fatal complication of antituberculous chemotherapy.

Intraperitoneal chemotherapy complicated by erosion of a Tenckhoff catheter into the colon.

Insertion and maintenance of intraperitoneal catheters must be done with meticulous attention to detail. We recommend insertion under direct vision to minimize the incidence of intestinal perforation during catheter placement. Intraperitoneal catheters should not be placed in close proximity to a fresh intestinal anastomosis because this position may promote anastomotic dehiscence. Communication between the catheter and the intestinal lumen necessitates catheter removal.

Intraoperative interstitial radiation therapy for hepatic metastases from colorectal carcinomas.

Liver metastases from colorectal carcinomas occur frequently. While surgical resection offers the only hope for long-term cure, unsuspected bilobar metastases or extrahepatic metastatic disease may be found at laparotomy, precluding hepatic resection for cure. In this setting intraoperative interstitial hepatic irradiation using the Gamma Med II (Mick Radio-Nuclear Instruments, Bronx, New York) remote afterloading irradiator and an Iridium-192 source permits delivery of a tumoricidal dose to liver tumor(s) with a limited radiation dose to adjacent normal liver. Six patients underwent laparotomy for potential resection of hepatic metastases in a shielded operating room equipped with remote anesthesia monitoring capability and were found to be unresectable. An upper hand retractor facilitated liver exposure during the exploratory and subsequent radiation phases of the procedure. Intraoperative interstitial radiation therapy was performed in each patient. No significant complications occurred on follow-up from 2 to 9 months. Hepatic tumor regression or stabilization occurred on sonography and/or CT scan in each case with a median follow-up of 5 months. The technique offers the potential to ablate discrete tumor nodules within the liver. Ongoing clinical trials will determine the role of intraoperative interstitial radiation in the treatment of hepatic metastases.

Bilateral pyopneumothorax secondary to intravenous drug abuse.

An intravenous drug abuser presented with bilateral pyopneumothoraces and bacteremia which is a previously unreported complication of jugular vein self-injection. The patient sustained direct pleural trauma and resultant infection by injecting herself with contaminated needles.