The impact of group B Streptococcus prophylaxis on early onset neonatal infections.

OBJECTIVE: To determine if changes have occurred in the causative pathogens and/or antibiotic susceptibility profiles in early onset neonatal infections since initiation of group B Streptococcus (GBS) prophylaxis and to determine risk factors for ampicillin/penicillin resistant microorganisms. STUDY DESIGN: Data on 220 infants with positive blood, urine, or cerebrospinal fluid cultures for bacteria or fungi at ≤seven days of age from 1990-2007 were examined and divided into three epochs, based on intrapartum antibiotic prophylactic (IAP) practices. Pathogens and antibiotic resistance were compared among epochs. RESULTS: A significant decrease in the incidence of GBS infections occurred over time, with no change in the incidence of other pathogens or the emergence of antibiotic resistance, including the very low-birthweight population. In regression analysis, ampicillin resistance was associated with male gender (OR 3.096). CONCLUSIONS: No emergence of antibiotic resistant pathogens was found following IAP use. Changing microorganisms and increasing antibiotic resistance found in prior studies are likely multifactorial. Further study is needed to continue to reduce the rates of common early onset pathogens.

The impact of group B streptococcus prophylaxis on late-onset neonatal infections.

OBJECTIVE: To determine trends in late-onset neonatal infections and risk factors for ampicillin/penicillin-resistant microorganisms. STUDY DESIGN: Data on 584 infants with positive blood, urine or cerebrospinal fluid cultures for bacteria or fungi at 8-30 days of age from 1990 to 2007 were examined and divided into three epochs, based on intrapartum antibiotic prophylactic (IAP) practices. Pathogens and antibiotic resistance were compared among epochs. RESULT: The number of candidal infections increased over time for the entire population (P=0.006). There was an increased incidence of Gram-negative (P=0.009) and candidal infections (P=0.014) among very low-birthweight infants. Only Escherichia coli infections showed increasing ampicillin resistance over epochs (P=0.006). In regression analysis, ampicillin/penicillin resistance increased with IAP use (odds ratio 2.05). CONCLUSION: Changing microorganisms and increasing antibiotic resistance in late-onset neonatal infections are likely multifactorial but are increased with IAP use, which may identify an at-risk population. Increasing Candida infections require further investigation.

Relationship between cerebrovascular dysautoregulation and arterial blood pressure in the premature infant.

OBJECTIVE: To evaluate cerebrovascular autoregulation as a function of arterial blood pressure (ABP) in the critically ill, premature infant. STUDY DESIGN: A prospective observational pilot study was conducted in two tertiary care Neonatal Intensive-Care Units. Premature infants (n=23, ≤30 weeks estimated gestational age with invasive ABP monitoring) were enrolled and received routine care while undergoing continuous autoregulation monitoring, using the cerebral oximetry index (COx). The COx is a moving, linear correlation coefficient between cortical reflectance oximetry and ABP. COx values were stratified as a function of ABP for individual subject recordings and for the cohort. RESULT: The mean duration of autoregulation monitoring was 3.2 days (median: 2.97, range: 0.61-3.99). A total of 10 of 23 (43%) developed intraventricular hemorrhage and 1 of 23 (4%) developed periventricular leukomalacia by head ultrasound. No association was found between neurologic injury and percentage of the monitoring periods with autoregulation impairment (defined as COx>0.5). Lower ABP was associated with dysautoregulation (higher COx values, P<0.01). The percentage of time with impaired autoregulation was greater with lower ABP (P=0.013, Spearman r=0.51). CONCLUSION: All infants studied had periods with intact and periods with impaired cerebrovascular autoregulation, measured with the COx. Low ABP was associated with impaired autoregulation.

Significance of internal mammary lymph nodes in patients after mastectomy with tissue-expander reconstruction: a case-control study.

AIM: To retrospectively assess the frequency of internal mammary lymph nodes (IMNs) in patients after mastectomy and tissue-expander reconstruction. MATERIALS AND METHODS: Statistical analysis was performed for all available data in patients with mastectomy and tissue-expander reconstruction from 2004-2007 (study group). The data were compared with that of a control population with mastectomy who did not have reconstruction (control group). Patients with recurrent breast cancers, previous breast reconstruction, surgeries performed at outside hospitals, no available pre- or postoperative computed tomography (CT) or magnetic resonance imaging (MRI) data, or inadequate imaging follow-up were excluded. RESULTS: There were eight patients in the study group (median age 50.5 years, seven breast cancers), and eight patients in the control group (median age 52 years, seven breast cancers). No patients had IMNs on their preoperative imaging examinations. New IMNs were present in postoperative imaging in seven of eight patients (7/8, 87.5%) in the study group. All of them were stable or decreased in size on subsequent imaging examinations. None of the patients in the control group had IMNs (0/8). CONCLUSION: IMNs are common on imaging after mastectomy and tissue-expander placement. The IMNs decreased or remained stable on follow-up imaging and may represent reactive nodes.

Acquired tracheomalacia: detection by expiratory CT scan.

PURPOSE: The purpose of this work was to determine whether cross-sectional area and coronal and sagittal diameter measurements of the trachea between inspiration and end-expiration on CT are significantly different between patients with acquired tracheomalacia and those without this condition. METHOD: Inspiratory and end-expiratory CT scans of the trachea of 23 normal patients and 10 patients with acquired tracheomalacia were analyzed. Percent changes in cross-sectional area, coronal, and sagittal diameters were calculated. RESULTS: For patients with tracheomalacia, mean percent changes in the upper and middle trachea between inspiration and expiration were 49 and 44%; mean changes in the coronal and sagittal diameters in the upper and middle tracheal were 4 and 10% and 39 and 54%, respectively. Control group mean percent changes in the upper and middle tracheal area were 12 and 14%, respectively, and mean changes in the coronal and sagittal diameters in the upper and middle trachea were 4 and 4% and 11 and 13%, respectively. Significant differences were calculated for changes in cross-sectional area and sagittal diameter between groups (p < 10-5). Based on receiver operator curve analysis, a > 18% change in the upper trachea and 28% change in the midtrachea between inspiration and expiration were observed; the probability of tracheomalacia was 89-100%. The probability of tracheomalacia was > 89%, especially if the change in sagittal diameter was > 28%. CONCLUSION: By measuring changes in tracheal cross-sectional area and sagittal diameters between inspiratory and end-expiratory CT, a significant difference can be identified between normal patients and those with acquired tracheomalacia.

Tuberculosis from head to toe.

Tuberculosis can affect virtually any organ system in the body and can be devastating if left untreated. The increasing prevalence of tuberculosis in both immunocompetent and immunocompromised individuals in recent years makes this disease a topic of universal concern. Because tuberculosis demonstrates a variety of clinical and radiologic findings and has a known propensity for dissemination from its primary site, it can mimic numerous other disease entities. Primary pulmonary tuberculosis typically manifests radiologically as parenchymal disease, lymphadenopathy, pleural effusion, miliary disease, or lobar or segmental atelectasis. In postprimary tuberculosis, the earliest radiologic finding is the development of patchy, ill-defined segmental consolidation. Both computed tomography (CT) and magnetic resonance (MR) imaging are helpful in diagnosing tuberculous spondylitis and tuberculous arthritis. CT is especially useful in depicting gastrointestinal and genitourinary tuberculosis. In tuberculosis involving the central nervous system, CT and MR imaging findings vary depending on the stage of disease and the character of the lesion. A high degree of clinical suspicion and familiarity with the various radiologic manifestations of tuberculosis allow early diagnosis and timely initiation of appropriate therapy, thereby reducing patient morbidity.

CT manifestations of respiratory syncytial virus infection in lung transplant recipients.

PURPOSE: The purpose of our study was to evaluate CT findings during respiratory syncytial virus (RSV) infection in lung transplant recipients and to identify sequelae. METHOD: Thirty-nine CT scans prior to, during, and following acute infection in 10 lung transplant recipients were reviewed. Abnormalities that were new from baseline observations and occurred within 4 weeks of diagnosis were defined as acute. Chronic findings were defined as those present >4 weeks after diagnosis. RESULTS: Findings in nine patients were ground-glass (seven), air-space (five), and tree-in-bud (four) opacities and acute bronchial dilatation (four) and wall thickening (four). Patients lacked pleural effusions or lymph node enlargement. Five of seven patients with follow-up exams had new air trapping (three), persistent bronchial dilatation (three), and thickening (two). Three and 2 of the 10 patients developed bronchiolitis obliterans syndrome and obliterative bronchiolitis, respectively. CONCLUSION: During acute infection, patients commonly had ground-glass opacities but lacked pleural effusions and lymph node enlargement. There can be chronic sequelae after infection.

Imaging of lung transplantation.

Lung transplantation is an accepted treatment for a large number of end-stage pulmonary diseases. There are several complications that pertain specifically to lung transplant recipients, including airway ischemia, reperfusion edema, infections, acute rejection, obliterative bronchiolitis, and other postoperative problems relating to surgical technique and immuno-suppressive therapy. Imaging procedures play an important role in the diagnosis and management of these problems.

Mediastinal lymphadenopathy and hazy mediastinal fat: new CT findings of congestive heart failure.

OBJECTIVE: We describe two new CT findings of congestive heart failure (CHF): enlarged mediastinal lymph nodes and hazy heterogeneous mediastinal fat. MATERIALS AND METHODS: Forty-six patients were retrospectively identified who had major and minor clinical signs of congestive heart failure and had undergone chest CT during their symptomatic period. Two radiologists reviewed the CT studies and by consensus documented the presence or absence of imaging findings of CHF, including interstitial abnormalities, vascular redistribution, axial thickening, pleural effusions, cardiac enlargement, and mediastinal abnormalities. RESULTS: Smooth septal thickening, bilateral pleural effusions, vascular redistribution, and cardiac enlargement were the most common CT findings in patients with CHF. Enlarged mediastinal lymph nodes and hazy mediastinal fat were seen in 55% and 33% of cases, respectively. In a cohort of 17 patients with elevated pressures in the pulmonary capillary wedge documented within 24 hr of CT, CT scans revealed lymphadenopathy in 14 patients (82%) and inhomogeneous fat in 10 patients (59%). CONCLUSION: Enlarged mediastinal lymph nodes and hazy mediastinal fat occur in patients with CHF and are revealed by CT. Lymphadenopathy in patients with CHF does not necessarily indicate malignancy or an infectious process.

Acute pulmonary embolism: assessment of helical CT for diagnosis.

PURPOSE: To determine the sensitivity and specificity of helical computed tomography (CT) for the diagnosis of acute pulmonary embolism. MATERIALS AND METHODS: This prospective study included 47 patients who underwent pulmonary arteriography for evaluation for possible acute pulmonary embolism. Tailored helical CT and pulmonary arteriography were performed within 24 hours of each other. Each CT scan was interpreted by two chest radiologists, blinded to arteriographic results, at two institutions. CT scan interpretations were compared with findings on bilateral selective pulmonary arteriograms interpreted by two vascular radiologists at one institution. RESULTS: Fifteen (32%) of 47 patients had angiographically proved pulmonary embolism. For the readers at the first institution, helical CT had 60% sensitivity, 81% specificity, 60% positive predictive value, 81% negative predictive value, and 75% overall accuracy. For the readers at the second institution, helical CT had 53% sensitivity, 97% specificity, 89% positive predictive value, 82% negative predictive value, and 83% accuracy. CONCLUSION: Detection of pulmonary embolism with helical CT may be less accurate than previously reported. Given its high specificity but relatively low sensitivity, helical CT may not have the ideal attributes of a first-line imaging study for the diagnosis of pulmonary embolism.

Imaging of mediastinal lymph nodes: CT, MR, and FDG PET.

The evaluation of mediastinal lymph nodes is an important aspect of staging in patients with non-small cell lung cancer. Anatomic imaging of lymph nodes with computed tomography (CT) and magnetic resonance (MR) imaging has been limited by the relatively low sensitivity and specificity of these techniques. Advances in physiologic imaging of mediastinal lymph nodes with 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) have resulted in improved diagnostic accuracy in the determination of nodal status. Despite the limitations of CT, this technique still plays an important role by aiding in the selection of the most appropriate procedure for staging, by guiding biopsy, and by providing anatomic information for visual correlation with FDG PET images. At present, anatomic MR imaging of lymph nodes is primarily a problem-solving tool for cases with inconclusive CT results. Physiologic MR imaging with iron oxide is an exciting area of investigation, and the accuracy of this technique is being assessed in clinical trials. Anatomic and physiologic imaging techniques should be considered complementary rather than competitive imaging strategies.

Respiratory syncytial virus-associated infections in adult recipients of solid organ transplants.

BACKGROUND: Although respiratory syncytial virus (RSV) infection is known to cause severe pulmonary infections in bone marrow transplant recipients, less is known concerning its clinical course, diagnosis, and treatment in solid organ transplant recipients. METHODS: We have conducted a retrospective review of seven cases of RSV infection in adult recipients of solid organ transplants. Four patients received lungs, two received kidneys, and one received a heart. RESULTS: The most common presenting complaints were dyspnea (100%), cough (86%), and purulent sputum (57%). Physical findings included fever (43%), rales (100%), and wheezing (29%). Admission studies were significant for leukocytosis (29%), a left shift in the white blood cell differential (86%), and hypoxemia (mean PaO2 = 64). Chest radiographs were unchanged in 29% and showed infiltrates that were bilateral in 43% and unilateral in 29%. Pulmonary function tests in lung transplant recipients showed a mean fall in forced expiratory volume in 1 second of 26% and a fall in diffusion capacity for carbon monoxide of 24%. Five patients were treated with aerosolized ribavirin. Adverse events associated with treatment included wheezing (80%) and mild dyspnea (20%). The conditions of three of five treated patients were believed by their physicians to have improved 7 days after the initiation of therapy. One of the five treated patients died, and both untreated patients survived. CONCLUSIONS: RSV infection in this population has an extremely variable severity and clinical course, usually dominated by lower respiratory symptoms and obstructive airway disease. Ribavirin therapy is well tolerated, but its efficacy remains unknown.

Routine addition of an automated biopsy device to fine-needle aspiration of the lung: a prospective assessment.

OBJECTIVE: The purpose of this study was to prospectively assess the usefulness of the routine addition of an automated biopsy device (ABD) to fine-needle aspiration (FNA) of the lung and to examine the complication rate of this procedure. SUBJECTS AND METHODS: Fifty biopsies were performed under CT guidance using a coaxial technique with a 19-gauge introducer needle and a 22-gauge aspirating needle followed by a 20-gauge ABD. An average of 3.5 FNA specimens and 2.5 core specimens were obtained. Cytology and histology specimens were interpreted separately by two experienced pathologists who were unaware of the other's interpretation. Final diagnoses were based on surgery, microbiology, definitive biopsy diagnosis, and clinical follow-up. All complications were recorded. RESULTS: Of 34 malignant lesions, we achieved a diagnostic accuracy of 94% for FNA and 59% for core biopsy (p < .01). Combined accuracy was 94%. Of 16 benign lesions, an accurate definitive diagnosis was made in 31% of cases using FNA and in 69% of cases using core biopsy (p = .08). Combined accuracy was 69%. In the subset of benign lesions that were not acute infections (n = 8), an accurate definitive benign diagnosis was made in 12% of cases using FNA and in 75% of cases using core biopsy (p < .05). No false-positive diagnoses of malignancy occurred. Complications included pneumothorax, nine (18%) of 50 cases; chest tube, one (2%) of 50 cases minor pulmonary hemorrhage, seven (14%) of 50 cases; and minor hemoptysis, two (4%) of 50 cases. CONCLUSION: The complication rates of FNA with the addition of an ABD are similar to those reported in the literature for FNA alone. The addition of an ABD significantly increases the diagnostic accuracy only for the subset of benign lesions that are not acute infections.

Postpneumonectomy syndrome: another twist.

This report describes the clinical, radiographic, and surgical findings in a patient with a rare postoperative complication, the postpneumonectomy syndrome. To our knowledge, it is the first reported case of postpneumonectomy syndrome after left pneumonectomy in a patient with a left-sided aortic arch.

Relationship between pulmonary artery diameter at computed tomography and pulmonary artery pressures at right-sided heart catheterization. Massachusetts General Hospital Lung Transplantation Program.

RATIONALE AND OBJECTIVES: The purpose of the study was to determine the relationship between pulmonary artery (PA) size at computed tomography (CT) and PA pressures, to develop a noninvasive CT method of PA pressure measurement, and to determine a PA diameter that can enable differentiation of normal subjects from those with pulmonary hypertension. METHODS: PA vessel diameters in 55 candidates for lung and heart-lung transplantation were measured at CT and correlated with PA pressures with both linear and stepwise multiple regression. The multiple regression equations were then tested prospectively in 35 pretransplantation patients. RESULTS: Combined main and left main PA cross-sectional area corrected for body surface area showed the best correlation with mean PA pressure (r = .87). The multiple regression equations helped predict mean PA pressure within 5 mm Hg in 50% of patients with chronic lung disease and in only 8% of patients with pulmonary vascular disease. CONCLUSION: There was a very good correlation between main and left main PA size and mean PA pressure. At present, however, CT has not demonstrated sufficient accuracy to be used clinically.

The costal cartilages in health and disease.

The costal margin, although imaged in many routine radiologic examinations, has been ignored in the radiology literature. Calcification of the costal cartilages follows gender-related patterns and is generally not evident radiographically until after the age of 30 years. Diffuse enlargement of the costochondral junctions may alert the astute observer to the presence of systemic diseases such as acromegaly and rickets. Focal masses have a subtle appearance on plain radiographs and may be better imaged with computed tomography (CT) or magnetic resonance imaging. Chondrosarcoma of the costal margin typically appears as an expansile mass with coarse calcifications and an associated soft-tissue mass. Radiographic and CT features of costochondritis include chondral enlargement or destruction, low-attenuation cartilage at CT, associated soft-tissue swelling, and localized peripheral cartilage calcification. There appears to be an association between heavy premature costal cartilage calcification and certain systemic conditions, such as malignancy, autoimmune disorders, chronic renal failure, and thyroid disease, particularly Graves disease.