Analysis of statistical outliers with application to whole effluent toxicity testing.

In this analysis, low-value outliers were detected in five data sets obtained from laboratory records. The effect of removing the outliers by three methods data rejection (asymmetrical and symmetrical trimming and Winsorization) revealed that all three methods slightly increased the mean and reduced the variance of the data sets. These opposing effects on the results of a hypothesis test of means were examined in the context of passing or failing a regulatory requirement significant difference between effluent concentration and a control. Analysis by statistical resampling of one data set showed that while all data rejection methods reduced the level of Type II error in a hypothesis test of no difference in reproduction between a test concentration and a regulatory limit, asymmetrical trimming was the best in this regard.

Pulmonary gangrene: radiological and pathologic correlation.

Although frequently referred to as pulmonary abscess or necrotizing pneumonia, pulmonary gangrene is a distinct entity, requiring prompt medical and often surgical management. Radiographically, it begins as a lobar consolidation, usually in the upper lobes, develops lucencies, and coalesces to form a cavity. A "mass within a mass" or air crescent sign may be present. A vasculitis ensues, devitalizing parenchyma that must be drained surgically or expectorated through a patent bronchus. Serious complications of pulmonary gangrene that often lead to death are detected on computed tomography (CT) before these changes are apparent on chest radiographs. Specifically, a narrowed or obliterated bronchus impedes drainage of necrotic parenchyma and thrombosis of large vessels prevents the delivery of antimicrobial therapy. We review the literature and report this case to show the importance of CT in the early detection and management of pulmonary gangrene.

CT evaluation of mediastinal masses in children: spectrum of disease with pathologic correlation.

The mediastinum is the site of a variety of benign and malignant pathological processes in children. While the chest radiograph may be the initial imaging study to suggest an abnormality, spiral or helical CT provides detailed depiction of anatomic relationships and characteristics of the mass, and may increase the likelihood of a successful examination because of shorter scan times. This article will emphasize the important CT features in the evaluation of common and uncommon mediastinal masses in children. Pathologic correlation is presented for greater understanding. In many clinical settings, CT features such as attenuation, enhancement, calcification, anatomic relationships and extent of disease may suggest a specific diagnosis for a mediastinal mass in a child.

CT evaluation of small bowel neoplasms: spectrum of disease.

Neoplasms of the small bowel are rare lesions that account for less than 5% of all gastrointestinal tumors. Although the differential diagnosis for a small bowel tumor is extensive, various small bowel neoplasms have characteristic features at computed tomography (CT) that may aid in making a diagnosis. Small bowel adenocarcinoma may appear at CT as an annular lesion, a discrete nodular mass, or an ulcerative lesion. Non-Hodgkin lymphoma may appear as a segmental bulky mass that gradually merges into the normal bowel wall. Lymphoma is characteristically associated with marked luminal dilatation. Carcinoid tumor may appear as an ill-defined homogeneous mass that displaces bowel loops. Calcification and desmoplastic reaction in a mesenteric mass suggest the diagnosis of carcinoid tumor. Gastrointestinal stromal tumors (GISTs), both benign and malignant, may be submucosal, subserosal, or intraluminal. The CT appearance of a GIST may include a sharply defined mass with homogeneous attenuation, sometimes with calcification. Lipoma appears at CT as a well-circumscribed, intraluminal homogeneous mass with fat attenuation. Most malignant small bowel tumors are actually metastases that have spread intraperitoneally, hematogenously, or by local extension. Intraperitoneal seeding usually manifests at CT as multiple small nodular metastases along the small bowel serosa, mesentery, and omentum. In patients with Peutz-Jeghers syndrome, nonneoplastic lesions may mimic small bowel neoplasms.

The accuracy of CT staging of small bowel adenocarcinoma: CT/pathologic correlation.

PURPOSE: Several studies have documented the use of CT in the evaluation of small bowel neoplasms, but few have addressed the CT staging of adenocarcinoma. We retrospectively correlated CT and pathologic staging to evaluate the accuracy of CT for staging small bowel adenocarcinoma using American Joint Committee on Cancer criteria. METHOD: The preoperative CT scans of 15 patients with pathologically proven small bowel adenocarcinoma were analyzed. Two blinded readers separately interpreted extent of invasion, presence of lymphadenopathy, and distant metastases. Pathologic and CT staging were compared. RESULTS: The overall accuracy of CT staging was 47% (14/30). The sensitivity of detection of mesenteric infiltration was 88%. The sensitivity and specificity for detection of distant metastases were 58 and 63% and for lymphadenopathy 75 and 20%, respectively. Errors occurred in patients with Crohn disease, adenomas, Peutz-Jegher syndrome, small bowel obstruction, and perforation and on suboptimal studies. CONCLUSION: The accuracy of CT staging of small bowel adenocarcinoma is 47%. CT is highly sensitive but not specific for the detection of mesenteric infiltration and regional lymphadenopathy. Since spiral CT may offer improved detection of distant metastases and increased accuracy in the evaluation of patients with concomitant bowel disease, further research is needed to determine the maximal utility of CT in the staging of adenocarcinoma of the small bowel.

Small bowel cancer. Imaging features and staging.

Small bowel neoplasms are relatively rare. This article presents the imaging features of the most frequently encountered small bowel masses, with emphasis on adenocarcinomas and carcinoid tumors. The CT scan findings and correlative barium and angiographic studies of various small bowel tumors are illustrated. The staging of adenocarcinoma of the small intestine is addressed, with attention to the role of CT scans for radiologic staging.

Transitional cell carcinoma of the renal pelvis: a retrospective look at CT staging with pathologic correlation.

PURPOSE: To identify the reasons for the discrepancies between computed tomographic (CT) and pathologic staging of transitional cell carcinoma of the renal pelvis and to develop new criteria to increase the accuracy of CT in staging. MATERIALS AND METHODS: CT scans of 31 consecutive patients with renal pelvic transitional cell carcinoma were evaluated. CT and pathologic staging were compared. RESULTS: Pathologic staging revealed four stage 0 tumors, three stage I, five stage II, 10 stage III, and nine stage IV. The initial overall CT staging accuracy was 52% (16 of 31 patients). The sensitivity for minimal invasion was 17% (two of 12 patients). Two-thirds (10 of 15 patients) of the misinterpreted cases were overstaged as stage III. Proximal hydronephrosis was present in 80% of overstaged cases (eight of 10 patients). Reevaluation of the CT studies by using proximal hydronephrosis as a criterion for minimal invasion improved overall CT staging accuracy (77%). The revised staging yielded a sensitivity of 83% and specificity of 95% for minimal invasion and improved the specificity for deep invasion (17% to 92%). CONCLUSION: In a patient with transitional cell carcinoma of the renal pelvis, hydronephrosis proximal to the tumor may cause overstaging of stage 0-II disease and may not indicate more advanced disease.

CT features of pulmonary nocardiosis.

OBJECTIVE: Our goal was to identify the CT features of pulmonary nocardiosis, specifically in AIDS patients versus other immunocompromised hosts. MATERIALS AND METHODS: Twenty-four patients with pulmonary nocardiosis were identified; medical records, CT scans, and chest radiographs were reviewed. Five patients had HIV disease, 17 had other causes of immunosuppression, and 2 had normal immunity. RESULTS: CT features of pulmonary nocardiosis included one or more nodules/masses (20/24 cases, 83%), cavitation (8, 33%), consolidation/infiltrates (8, 33%), and pleural thickening (7, 29%). All AIDS patients with nocardiosis had multiple (four or more) nodules detected on CT and 80% (4/5) had cavitation compared with 21% each of non-AIDS patients (p < 0.01 for multiple nodules, p < 0.045 for cavitation). CONCLUSION: CT features of pulmonary nocardiosis are varied, and AIDS patients are more likely to display cavitation and multiple nodules. Although not widely recognized, Nocardia infection should be included in the differential diagnosis of an unexplained nodule or progressive cavitary process in HIV-positive patients.

Pulmonary nodules: effect of increased data sampling on detection with spiral CT and confidence in diagnosis.

PURPOSE: To compare spiral computed tomography (CT) with interscan spacing of 4-5 mm versus 8-10 mm for detection rate and level of confidence in diagnosis of pulmonary nodules. MATERIALS AND METHODS: Four radiologists (two junior and two senior faculty members) retrospectively reviewed 67 spiral CT studies with one to six nodules per study. Every second image was masked, which resulted in 8-mm sections every 8 or 10 mm; then all images reconstructed every 4 or 5 mm were reviewed. Lesions were classified as definite, probable, or possible. RESULTS: Narrow interscan spacing yielded more lesions overall (583 vs 566, P < .025) and more definite lesions and fewer equivocal lesions (482 vs 431 and 101 vs 135, respectively; P < .055). The greatest effects were in the reduction of possible lesions (50 vs 88, P < .001) and in the reduction of false-positive diagnoses made by less experienced radiologists. CONCLUSION: Increased reconstruction frequency of spiral CT volume data sets improves detection of pulmonary nodules and enhances confidence in the diagnosis.

Association of hepatic veno-occlusive disease with the acquired immunodeficiency syndrome.

AIMS: Observation of a patient with the acquired immunodeficiency syndrome and veno-occlusive disease (VOD) at autopsy prompted us to review the liver pathology of autopsied patients with human immunodeficiency virus seropositivity and/or acquired immunodeficiency syndrome (HIV/AIDS) to determine the frequency of occurrence of VOD and the circumstances in which it arose. METHODS: the patients studied had been autopsied at The Johns Hopkins Hospital, a referral center, between April 1981 and July 1993. We reviewed 275 adult HIV/AIDS patients autopsied with liver slides available for evaluation. Twenty cases fulfilled the pathologic criteria for VOD, central vein obliteration and sclerosis, sinusoidal congestion and fibrosis, and perivenular hepatocellular degeneration and necrosis. The autopsy cases were compared for age, race, gender, duration of HIV infection, and risk factor for the acquisition of HIV infection. The clinical and pathologic features of the 20 cases with VOD were reviewed. RESULTS: of the 275 HIV/AIDS patients, 20 (7.3%) had VOD. The average age was 41 yr (range 30-58) and most cases were black males (15 black, 5 white, and 18 male). The duration of HIV infection ranged from 6 mo to 8 yr (mean, 19 mo). The risk factor for acquiring HIV infection was primarily intravenous drug abuse (12 of 20, 60%). Six patients had homosexual or bisexual contacts, and two had other or unknown risk factors. In contrast, among the total of 275 HIV/AIDS autopsied patients reviewed, only 72 (26%) reported intravenous drug abuse whereas 157 (57%) individuals listed homosexual or bisexual contacts as a risk for developing HIV infection. Forty-six patients (17%) had other or unknown means of HIV infection. Statistical analysis by risk factor showed that intravenous drug abuse was statistically significant as a predictor for the development of VOD in an HIV/AIDS patient (P < 0.005). CONCLUSIONS: VOD of the liver can be seen in patients with HIV/AIDS and is associated with intravenous drug abuse.

Epidermal growth factor-mediated apoptosis of MDA-MB-468 human breast cancer cells.

MDA-MB-468 human breast cancer cells lack estrogen receptors, overexpress epidermal growth factor (EGF) receptors, and are growth inhibited by EGF. We show that treatment of MDA-MB-468 cells with EGF leads to inhibition of cell proliferation, fragmentation of DNA into nucleosomal oligomers, and the development of apoptotic morphology. This treatment is associated with increased expression of c-myc, c-fos, jun family members, and transforming growth factor beta 1 mRNA and with partial proteolytic cleavage of poly(ADP-ribose) polymerase and lamin B. The observation that EGF can mediate apoptosis in EGF receptor-overexpressing cells has important implications for clinical efforts directed at the EGF receptor.

Development of a bone marrow culture for maintenance and growth of normal human B cell precursors.

The absence of long term bone marrow cultures for studying the growth and differentiation of human B cell precursors (BCP) has placed restrictions on the ability to analyze the early stages of human B cell ontogeny. We now describe a bone marrow-derived adherent cell microenvironment that maintains human BCP for several weeks in vitro. The adherent cells are maintained in a serum-free tissue culture medium, and consist of a predominant population of CD10+ fibroblast-like cells and a minor population of CD10+/nonspecific esterase+ macrophages. Adherent cell cultures seeded with fresh or cryopreserved fetal bone marrow, or purified CD10+/surface IgM- cells, provide a supportive microenvironment for lymphoid cells with a predominant phenotype of CD10+/CD19+/HLA-DR+/surface IgM-. Supplementation of the adherent cell cultures with human IL-7 induces active growth of BCP during the first 14 to 21 days of culture. However, the expansion of these cells does not continue past 21 days, and the cultures undergo a steady decline in BCP. Analysis of adherent cell conditioned medium revealed the presence of an unidentified soluble factor (or factors) that acts in concert with IL-7 to promote the growth of CD10+/surface IgM- cells. This culture system will be useful in elucidating the patterns of gene expression and growth factor requirements that characterize normal human B cell ontogeny, and perturbations of normal B cell ontogeny that lead to immunodeficiency and leukemia.