Mixed infiltrative and obstructive disease on high-resolution CT: differential diagnosis and functional correlates in a consecutive series.

Fourteen of 400 consecutive patients having high-resolution computed tomography (HRCT) with expiratory images showed findings of infiltrative lung disease on inspiratory HRCT and air trapping on expiratory CT. Diagnoses included hypersensitivity pneumonitis, sarcoidosis, atypical infection, and pulmonary edema. The extent of infiltrative abnormalities and air trapping were correlated with pulmonary function tests (PFT) in 11 patients. PFT indicated a mixed pattern in five, an obstructive pattern in three, and a restrictive pattern in three. Forced expiratory volume (FEV) in 1 second/forced vital capacity (FVC) correlated significantly with the extent of air-trapping (r = 0.60; p = 0.05). The extent of infiltrative abnormalities correlated significantly and negatively with forced vital capacity (r = -0.82, p = 0.002), FEV1 (r = -0.59, p = 0.05), total lung capacity (TLC) (r = -0.67, p = 0.05), and DLCO (r = -0.75, p = 0.02). Findings of lung infiltration on inspiratory HRCT scans and air trapping on expiratory CT correlated respectively with PFT measures of restrictive and obstructive lung disease.

Mediastinal lymphadenopathy: diagnostic yield of transbronchial mediastinal lymph node biopsy with CT fluoroscopic guidance-initial experience.

PURPOSE: To determine whether the use of computed tomographic (CT) fluoroscopy to guide transbronchial needle aspiration (TBNA) of mediastinal lymph nodes can improve the diagnostic yield. MATERIALS AND METHODS: CT fluoroscopy was used to guide TBNA in 12 consecutive patients with mediastinal lymphadenopathy who had previously undergone nondiagnostic conventional TBNA. CT fluoroscopy was used to confirm the location of the biopsy needle by using a "quick-check" technique (ie, fluoroscopy was performed sparingly after needle insertion). The location of each needle, the total procedural and fluoroscopic times, and any complications were recorded. RESULTS: All CT fluoroscopic procedures were performed in less than 1 hour, and a tissue diagnosis was established in all patients. Eighteen lymph nodes with a diameter of 0.8-2.4 cm were sampled with 116 needle passes. CT fluoroscopy documented inadequate positioning in 48 of the 116 (41.3%) needle passes. Eighteen (15.5%) needles did not fully penetrate the tracheobronchial tree. Six needles (5.2%) were placed into the great vessels. Malignant disease was diagnosed in nine patients, and benign disease was diagnosed in three. The mean fluoroscopic exposure time was 20.5 seconds +/- 12.7. No pneumothoraces or substantial hemorrhage were observed. CONCLUSION: CT fluoroscopic guidance for TBNA procedures is a safe and efficient means of providing diagnostic material and should be considered for patients who have previously undergone nondiagnostic blinded TBNA.

Magnetic resonance imaging of the thorax. Past, present, and future.

Magnetic resonance imaging is a valuable modality of extreme flexibility for specific problem-solving capability in the thorax. This article reviews MR applications in the imaging of great vessels, which are currently the most important applications in the thorax; other established applications in the thorax; and pulmonary functional MR imaging.

Clinical and radiographic predictors of the etiology of pulmonary nodules in HIV-infected patients.

STUDY OBJECTIVES: To determine the etiology and the clinical and radiographic predictors of the etiology of pulmonary nodules in a group of HIV-infected patients. DESIGN: Retrospective analysis. SETTING: A large urban hospital in San Francisco, CA. PATIENTS: HIV-infected patients evaluated at San Francisco General Hospital from June 1, 1993, through December 31, 1997, having one or more pulmonary nodules on chest CT. MAIN OUTCOME MEASURES: Three physicians reviewed medical records for clinical data and final diagnoses. Three chest radiologists blinded to clinical data reviewed chest CTs. Univariate and multivariate analyses were performed to determine clinical and radiographic predictors of having an opportunistic infection and the specific diagnoses of bacterial pneumonia and tuberculosis. RESULTS: Eighty seven of 242 patients (36%) had one or more pulmonary nodules on chest CT. Among these 87 patients, opportunistic infections were the underlying etiology in 57 patients; bacterial pneumonia (30 patients) and tuberculosis (14 patients) were the most common infections identified. Multivariate analysis identified fever, cough, and size of nodules < 1 cm on chest CT as independent predictors of having an opportunistic infection. Furthermore, a history of bacterial pneumonia, symptoms for 1 to 7 days, and size of nodules < 1 cm on CT independently predicted a diagnosis of bacterial pneumonia; a history of homelessness, weight loss, and lymphadenopathy on CT independently predicted a diagnosis of tuberculosis. CONCLUSIONS: In HIV-infected patients having one or more pulmonary nodules on chest CT scan, opportunistic infections are the most common cause. Specific clinical and radiographic features can suggest particular opportunistic infections.

Multiple pulmonary nodules in AIDS: usefulness of CT in distinguishing among potential causes.

PURPOSE: To determine whether the computed tomographic (CT) appearances of multiple pulmonary nodules in patients with acquired immunodeficiency syndrome (AIDS) can help differentiate the potential infectious and neoplastic causes. MATERIALS AND METHODS: The thoracic CT scans obtained in 60 patients with AIDS and multiple pulmonary nodules were reviewed retrospectively by two thoracic radiologists who were blinded to clinical and pathologic data. The scans were evaluated for nodule size, distribution, and morphologic characteristics. CT findings were correlated with final diagnoses. RESULTS: Thirty-six (84%) of 43 patients with opportunistic infection had a predominance of nodules smaller than 1 cm in diameter, whereas 14 (82%) of 17 patients with a neoplasm had a predominance of nodules larger than 1 cm (P <.001). Of the 43 patients with opportunistic infection, 28 (65%) had a centrilobular distribution of nodules; only one (6%) of 17 patients with a neoplasm had this distribution (P <.001). Seven (88%) of eight patients with a peribronchovascular distribution had Kaposi sarcoma (P <.001). CONCLUSION: In patients with AIDS who have multiple pulmonary nodules at CT, nodule size and distribution are useful in the differentiation of potential causes. Nodules smaller than 1 cm, especially those with a centrilobular distribution, are typically infectious. Nodules larger than 1 cm are often neoplastic. A peribronchovascular distribution is suggestive of Kaposi sarcoma.

Magnetic resonance imaging of the thorax. Past, present, and future.

Magnetic resonance is a valuable modality of extreme flexibility for specific problem-solving capability in the thorax. This article reviews MR applications in the imaging of great vessels, which are currently the most important applications in the thorax; other established applications in the thorax; and pulmonary functional MR imaging.

Measurement of fibroblast proliferative activity in bronchoalveolar lavage fluid in the analysis of obliterative bronchiolitis among lung transplant recipients.

BACKGROUND: Bronchiolitis obliterans occurs in 30% to 80% of lung-transplant recipients and is a direct cause of death in more than 40% of patients with this complication. This study assessed the potential utility of measuring fibroblast-proliferative activity in bronchoalveolar lavage fluid from lung-transplant recipients to better understand the pathogenesis of this process. METHODS: The capacity of bronchoalveolar lavage fluid obtained from transplant recipients, during routine surveillance bronchoscopy, to stimulate the proliferation of human lung fibroblasts in vitro was assessed retrospectively and compared to that of control subjects. For each recipient, a correlation was made between the fibroblast-proliferative activity in serial lavage samples over time and the other modalities employed for detecting post-transplant complications including spirometry, transbronchial lung biopsy, and high-resolution computed tomography. RESULTS: There was a significant difference in fibroblast-proliferative activity between volunteer and transplant recipient groups (p = 0.002). Further, for each transplant recipient, the decline in the forced expired flow rate between 25% and 75% of expired volume (FEF(25%-75%)) was correlated with the mean fibroblast-proliferative activity during the period of this study (r = 0.83; p = 0.04). CONCLUSIONS: A sustained increase in fibroblast-proliferative activity in lavage supernatant precedes both histologic and physiologic evidence of bronchiolitis obliterans. Relative to an increase in fibroblast-proliferative activity or abnormalities in FEF25%-75%, a decrease in forced expiratory volume in 1 second is a late finding.

Imaging evaluation of suspected pulmonary embolism.

Venous thromboembolism (VTE) is a common disorder that is difficult to diagnose clinically but carries significant morbidity and mortality if untreated. Additionally, although demonstrated to be of benefit in cases of proven deep vein thrombosis (DVT) and pulmonary embolism (PE), anticoagulation therapy is not without risk. Because the clinical exam is known to be unreliable for the detection of both DVT and PE, many imaging modalities have been used in the diagnostic imaging algorithm for the detection of VTE, including chest radiography, ventilation/perfusion (V/Q) scintigraphy, pulmonary angiography, and recently, spiral computed tomography (CT) and magnetic resonance imaging (MRI). Chest radiographic findings in acute PE include focal oligemia, vascular enlargement, atelectasis, pleural effusions, and air space opacities representing pulmonary hemorrhage or infarction. The chest radiograph can occasionally be suggestive of PE but is more often nonspecifically abnormal. The main use of the chest radiograph in the evaluation of suspected PE is to exclude entities that may simulate PE and to assist in the interpretation of V/Q scintigraphy. Lower extremity venous compression ultrasonography (CU) is both sensitive and specific for the diagnosis of femoropopliteal DVT, and the value of negative CU results has been established in outcomes studies. However, the reliability of CU for the detection of isolated calf vein thrombosis is not well established, and the clinical significance of such thrombi is debatable. Additional methods such as color and spectral Doppler analysis are also useful in the diagnostic evaluation of DVT but are best considered as adjuncts to the conventional CU examination rather than as primary diagnostic modalities themselves. Compression ultrasonography and Doppler techniques are useful in the evaluation of suspected upper extremity DVT; spectral Doppler waveform analysis is particularly useful to assess for the patency of veins that cannot be directly visualized and compressed with conventional gray-scale sonography. V/Q scintigraphy has been the initial modality obtained in patients suspected of PE for a number of years. Although many studies have investigated the role of V/Q scintigraphy in the evaluation of VTE, the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study has provided the most useful information regarding the utility of V/Q scintigraphy in this setting. A high probability scan interpretation is sufficient justification to institute anticoagulation, and a normal perfusion scan effectively excludes the diagnosis of PE. A normal/near normal scan interpretation also carries a sufficiently low prevalence of angiographically proven PE to withhold anticoagulation. Although the prevalence of PE in the setting of low probability scan interpretations is low and several outcomes studies have demonstrated a benign course in untreated patients with low probability scan results, patients with inadequate cardiopulmonary reserve do not necessarily have good outcomes. Such patients deserve more aggressive evaluation. Patients with intermediate probability scan results have a 20% to 40% prevalence of angiographically proven PE and thus require further investigation. The radionuclide investigation of DVT includes such techniques as radionuclide venography and thrombus-avid scintigraphy. Although these methods have not been as thoroughly evaluated as CU, studies thus far have indicated encouraging results, and further investigations are warranted. Pulmonary angiography has been the gold standard for the diagnosis of PE for decades. Studies have indicated that angiography has probably been underutilized by referring physicians for the evaluation of suspected PE, likely because of the perception of significant morbidity and mortality associated with the procedure. (ABSTRACT TRUNCATED)

MR imaging of pulmonary parenchyma with a half-Fourier single-shot turbo spin-echo (HASTE) sequence.

OBJECTIVE: To evaluate the utility of a half-Fourier single-shot turbo spin-echo sequence (HASTE) at depicting lung parenchyma and lung pathology. METHODS AND PATIENTS: A HASTE sequence was applied to five normal volunteers and 20 patients with various pulmonary disorders to depict the lung parenchyma. Images were acquired with ECG-triggering and breath-holding. In three volunteers, signal intensity measurements from lung parenchyma were performed using four sequences: (a) HASTE; (b) conventional spin echo; (c) fast spin echo; and (d) gradient echo. T2 maps were produced using the HASTE acquisition. RESULTS: Minimal respiratory or cardiac motion artifacts were observed. The signal-to-noise ratios from lung parenchyma were 27.8 +/- 5.4, 22.0 +/- 3.0, 15.3 +/- 0.9, and 6.0 +/- 1.9 for HASTE, spin-echo, fast spin-echo, and gradient echo sequences, respectively. The scan time for HASTE was 302 ms for each slice. The T2 values in the right lung and the left lung were 61.2 +/- 4.1 and 79.1 +/- 8.9 ms in systole and 92.6 +/- 5.8 and 97.5 +/- 12.2 ms in diastole, respectively (P < 0.05 diastole versus systole). The HASTE sequence demonstrated clearly various pulmonary disorders, including lung cancer, hilar lymphadenopathy, metastatic pulmonary nodules as small as 3 mm, pulmonary hemorrhage, pulmonary edema and bronchial wall thickening in bronchiectasis. CONCLUSION: Our preliminary results indicate that the HASTE sequence provides a practical means for breath-hold MR imaging of lung parenchyma.

Pulmonary function improves after expandable metal stent placement for benign airway obstruction.

STUDY OBJECTIVE: To determine whether expandable metal stent placement for benign airway lesions improves pulmonary function. DESIGN: Case series. SETTING: University medical center. PATIENTS: Nine patients who underwent balloon-mediated expandable metal stent deployment for airway obstruction due to benign etiologies. RESULTS: All nine patients had expandable stents deployed for benign airway lesions using fiberoptic bronchoscopy and fluoroscopic guidance. Pulmonary function improved after stent placement. The mean FVC increased by 388 mL (95% confidence interval [CI], 30 to 740 mL), the mean peak expiratory flow (PEF) increased by 1,288 mL (95% CI, 730 to 1,840 mL), the mean FEV1 increased by 550 mL (95% CI, 240 to 860 mL), and the mean forced expiratory flow between 25% and 50% of vital capacity (FEF25-75%) increased by 600 mL (95% CI, 110 to 1,090 mL). Corresponding relative measurements included increases in FVC (12%), PEF (95%), FEV1 (38%), and FEF25-75% (87%). The complete characterization of a benign airway obstruction generally required a multimodal approach. CONCLUSIONS: Expandable metal stent placement appears to be an effective therapy for benign airway obstruction.

Characterization of rat schwannoma-Schwann cell hybrids.

Sciatic nerve Schwann cells from strain LEC rats, homozygous for the c form of 6-phosphogluconate dehydrogenase (6-PGD), and RN22 rat Schwannoma cells, a subclone of RN2 deficient in hypoxanthine phosphoribosyltransferase and expressing the s form of 6-PGD, were fused to produce 'RNS' hybrid clones which proliferate rapidly in a medium containing hypoxanthine, aminopterin and thymidine (HAT) and express c, s and c/s heterodimeric forms of 6-PGD. RNS cells, like both parents, maintain a high baseline activity of 2', 3'-cyclic nucleotide 3'-phosphohydrolase and, as in RN22, activity of this enzyme is further inducible by 1 mM N6, O2'-dibutyryl 3', 5'-cyclic AMP. The RNS clones resemble normal Schwann cells in the capacity to bind radioiodinated axolemmal fragments to their plasma membranes.