Features of non-small cell lung carcinomas overlooked at digital chest radiography.

PURPOSE: To examine the imaging features of non-small cell lung carcinomas (NSCLC) overlooked at digital chest radiography (dCXR), and compare general and thoracic radiologists' performance for lung carcinoma detection at dCXR. METHODS: Frontal and lateral dCXR from 30 consecutive patients with lung carcinoma overlooked during initial interpretation and 30 normal controls were independently retrospectively reviewed by two blinded thoracic radiologists and, in a separate review, three blinded general radiologists. The location, size, histopathology, borders, presence of superimposed structures, and lesion opacity were recorded. Interobserver agreement was calculated, and the detection performance between thoracic and general radiologists was compared. RESULTS: The average patient age was 67.9 years (range 47-82 years). The average size of carcinomas missed by the thoracic radiologists was 18.1mm (range 10-32 mm). Lesion margins were circumscribed in 29% (2/7), and 71% (5/7) of missed lesions were obscured by anatomical superimposition. Seventy-one percent (5/7) of missed lesions were solid nodules on computed tomography (CT) images. Forty-three percent of lesions were located in the upper lobes and 63% were adenocarcinomas. Compared with general radiologists, the seven NSCLC missed by the thoracic radiologists tended to be smaller (p=0.063), had significantly lower CT density measurements (-92.4+/-87.5 HU versus -70+/-87.2 HU, p=0.050), and more commonly had an ill-defined margin (p=0.026). The clinical stage of the overlooked lesions did not differ between the two groups (p=0.480). CONCLUSIONS: The lesion size, location, conspicuity, and histopathology impact the likelihood of lung carcinoma detection at dCXR in a fashion similar to that of conventional film-screen techniques.

Acute rejection following lung transplantation: limitations in accuracy of thin-section CT for diagnosis.

PURPOSE: To evaluate the sensitivity, specificity, predictive values, and accuracy of thin-section computed tomography (CT) for the diagnosis of acute rejection following lung transplantation and to determine whether any individual CT abnormalities are associated with histopathologically proved acute rejection. MATERIALS AND METHODS: Thin-section CT studies from 64 lung transplant recipients were retrospectively reviewed. CT studies were temporally correlated with various grades of biopsy-proved acute rejection (n = 34); 30 other CT studies were from a control group with no histopathologic evidence of acute rejection. Acute rejection was diagnosed as present or absent, and the diagnostic was calculated. RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CT for the diagnosis of acute rejection were as follows: 35%, 73%, 60%, 50%, 53%, respectively. No individual CT finding was significantly associated with acute rejection. The sensitivity of CT for the detection of various grades of acute rejection was 17% for grade A1, 50% for grade A2, and 20% for grade A3. The combination of volume loss and septal thickening, with or without pleural effusion, was never seen in the absence of acute rejection. CONCLUSION: Thin-section CT has limited accuracy for the diagnosis of acute rejection following lung transplantation, and no individual CT finding is significantly associated with this diagnosis.

Multidetector-row spiral computed tomography in the diagnosis of thoracic diseases.

Since its introduction in 1992, spiral computed tomography (CT) scanners constructed with a single row of detectors have revolutionized imaging of thoracic diseases. Current state-of-the-art models use up to 16 detectors and are capable of acquiring 4 contiguous slices of data with each gantry rotation; systems with 8 data acquisition units (and more) are currently in development. The principal advantages offered by these systems are increased scanning speed and the ability to obtain volumetric data in high resolution. These features enable imaging with enhanced contrast concentration, decreased contrast load, decreased respiratory and cardiac motion artifact, and multiplanar and 3-dimensional reconstruction capabilities. Herein we first review the technical aspects of multidetector spiral CT scanning. The arrangement and various combinations of the detector rows are discussed. Key scanning variables, including collimation (slice thickness), pitch (the rate of table travel per gantry rotation divided by the beam collimation), and gantry speed, are briefly addressed in the context of their interrelationships. Comparison is made with single-detector-row systems to emphasize the superior scanning speed and resolution. We then discuss the various clinical applications of multidetector spiral CT, including CT pulmonary angiography, CT aortography, virtual bronchoscopy, and multiplanar and 3-dimensional reconstructions.

Sarcoidosis presenting as an enlarging solitary pulmonary nodule.

Sarcoidosis is generally not considered in the differential diagnosis of solitary pulmonary nodules. We recently encountered a case in which preoperative awareness of this presentation of sarcoidosis allowed a limited pulmonary resection with resultant lower morbidity and potential preservation of lung function to be performed. Although rare, sarcoidosis should be considered in the differential diagnosis of solitary pulmonary nodules.

Comparison between MR imaging and 99mTc MIBI scintigraphy in the evaluation of recurrent of persistent hyperparathyroidism.

PURPOSE: To compare the sensitivity and positive predictive value of magnetic resonance (MR) imaging and technetium 99m 2-methoxyisobutyl-isonitrile (MIBI) scintigraphy for the detection of hyperfunctioning parathyroid tissue when used alone and in combination in a large patient population with recurrent or persistent hyperparathyroidism (HPT). MATERIALS AND METHODS: In 98 consecutive patients with biochemically proved recurrent or persistent HPT after surgery, MR imaging and 99mTc MIBI study findings were retrospectively reviewed and compared with surgical and histopathologic findings. The sensitivity and positive predictive value of MR imaging and 99mTc MIBI scintigraphy were compared with each other and in combination. RESULTS: In these patients, 130 abnormal parathyroid glands were identified at surgery. The sensitivity and positive predictive value of MR imaging were 82% (95% CI: 75%, 89%) and 89%, respectively; those for (99m)Tc MIBI scintigraphy were 85% (95% CI: 79%, 91%) and 89%. No significant difference was found between MR imaging and 99mTc MIBI scintigraphy for sensitivity (P =.7). The sensitivity and positive predictive value for the detection of abnormal parathyroid tissue on a per-gland basis increased to 94% (95% CI: 90%, 98%) and 98%, respectively, when only one of the two tests was required to be positive. CONCLUSION: MR imaging and 99mTc MIBI scintigraphy have similarly good sensitivity and positive predictive value for the detection of hyperfunctioning parathyroid tissue in patients after surgery. The combination of the two tests provided a substantial increase in sensitivity and positive predictive value.

Minute pulmonary meningothelial-like nodules: thin-section CT appearance.

Minute pulmonary meningothelial-like nodules are often incidentally discovered during pathologic evaluation of pulmonary parenchymal specimens. These lesions were once thought to represent pulmonary chemodectomas, but pathological studies have shown that they are not of neuroendocrine origin. Minute pulmonary meningothelial-like nodules are benign, perhaps reactive in nature, but are occasionally found in association with lung carcinoma. They may appear as randomly distributed well-defined micronodules on thin-section chest CT, and thus may simulate metastatic disease when associated with lung carcinoma.

Hypersensitivity pneumonitis: patterns on high-resolution CT.

Hypersensitivity pneumonitis, also known as extrinsic allergic alveolitis, is caused by inhalation of specific environmental organic antigens. This disease may have typical high-resolution CT findings that, in the appropriate clinical setting, can be sufficiently characteristic to allow a confident diagnosis without the need for a lung biopsy. In this pictorial essay, the high-resolution CT patterns of hypersensitivity pneumonitis are illustrated. The authors emphasize the correlation among the radiologic presentation, functional abnormalities, and pathologic findings.

Early bronchiolitis obliterans following lung transplantation: accuracy of expiratory thin-section CT for diagnosis.

PURPOSE: To evaluate the accuracy of thin-section computed tomography (CT) with expiratory scans in diagnosing early bronchiolitis obliterans after lung transplantation. MATERIALS AND METHODS: Thin-section CT scans were reviewed by two observers blinded to the diagnoses in seven consecutive lung transplant recipients with histopathologically proved bronchiolitis obliterans (group A) and 21 with normal biopsy findings (group B). All patients had normal biopsy and stable pulmonary function test (PFT) results 2-36 weeks prior to CT. Patients with normal biopsy results were placed into subgroups based on abnormal (group B1) or stable (group B2) PFT results. Air-trapping extent on expiratory scans was scored on a 24-point scale. RESULTS: The mean air-trapping score in group A (6.6) was not significantly different from that in group B (4.5, P =. 17). The air-trapping score was significantly higher in groups A and B1 than in group B2 (6.2 and 2.6, respectively; P =.03). The frequency of an air-trapping score of 3 or more in groups A and B1 was significantly higher than that in group B2 (P =.03). By using a score of 3 or more to indicate air trapping, the sensitivity of expiratory CT was 74%, specificity was 67%, and accuracy was 71%. CONCLUSION: Thin-section CT, including expiratory scans, is of limited accuracy in diagnosing early bronchiolitis obliterans after lung transplantation.

Low-dose, dynamic, expiratory thin-section CT of the lungs using a spiral CT scanner.

Seventeen patients with lung transplants were evaluated with inspiratory, postexpiratory, and low-dose, dynamic expiratory thin-section computed tomography (CT). Region of interest measurements were performed on inspiration and expiration images with both techniques, and mean lung attenuation changes between inspiration and expiration images were calculated and compared. Dynamic expiratory thin-section CT resulted in a significantly greater increase in lung attenuation than postexpiratory thin-section CT. Dynamic expiratory thin-section CT may prove useful in the evaluation of patients with lung diseases characterized by air flow obstruction with little increase in patient radiation dose.

Incidental detection of thoracic sarcoidosis on whole-body 18fluorine-2- fluoro-2-deoxy-D-glucose positron emission tomography.

18 Fluorine-2- Fluoro-2-Deoxy-D-Glucose positron emission tomography (18FDG PET) allows imaging of sites with increased metabolic activity. Increased metabolic activity in mediastinal nodes in sarcoidosis has been described. We report the prospective diagnosis of thoracic sarcoidosis on 18FDG PET based on extensive, peripheral, upper lobe parenchymal, and mediastinal nodal tracer uptake.

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.

MR imaging of the thyroid and parathyroid glands.

Whereas scintigraphy and ultrasonography are the primary imaging modalities used for the investigation of thyroid disorders, MR imaging is generally used for specific indications, including evaluating the extent of substernal goiters, assessing the effect on adjacent structures, imaging the local extent of thyroid carcinomas, and localizing recurrent sites of thyroid neoplasia. MR imaging also has been used for the investigation of congenital disorders of the thyroid gland and the evaluation of diffuse thyroid disease, such as Grave's disease, Hashimoto's and Riedel thyroiditis, and hemochromatosis. MR imaging of the parathyroid glands is generally used for patients with recurrent or persistent hyperparathyroidism following neck exploration. MR imaging provides useful information about morphologic abnormalities of the thyroid and parathyroid glands. MR imaging has good sensitivity and positive predictive value for the identification of non-ectopic and ectopic abnormal parathyroid glands. The detailed anatomic information provided by MR imaging is useful in planning a surgical approach and is complementary to other imaging methods used in the investigation of recurrent or persistent hyperparathyroidism.

Helical CT for the evaluation of suspected acute pulmonary embolism: diagnostic pitfalls.

Helical CT is being increasingly utilized for the evaluation of suspected pulmonary embolism (PE). Proper scan interpretation depends on the awareness of several diagnostic pitfalls that may simulate PE, including normal bronchovascular structures such as pulmonary veins, bronchi, and lymph nodes, technical considerations such as improper bolus timing and streak artifacts, and patient-related factors such as motion artifacts, pulmonary arterial catheters, and vascular shunts. An understanding of these pitfalls facilitates accurate diagnosis.

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)

Circulating levels of insulin-like growth factor binding protein-1 (IGFBP-1) and hepatic mRNA are increased in the small for gestational age (SGA) fetal rat.

Insulin-like growth factors (IGFs) circulate in association with a family of specific binding proteins (BPs). Recently, we reported that circulating levels of IGFBP-1 and IGFBP-2 are increased in streptozotocin-diabetic adult rats and are differentially regulated in accordance with insulin and metabolic status. Since IGF BPs appear to be important modulators of IGF bioactivity in post-natal life, we asked whether serum levels of IGF BPs also might be altered in utero when the delivery of maternal nutrients is restricted and fetal growth is impaired. Bilateral uterine artery ligation or sham surgery was performed on maternal rats on d 19 of gestation (term 21.5 d). One day after ligation (d 20), fetuses were (SGA) compared to shams (3.1 +/- 1 vs 3.7 +/- 0.2 g, p less than .02) and serum levels of glucose (70 +/- 5 vs 96 +/- 6 mg/dL, p less than .01) and insulin (62 +/- 4 vs 138 +/- 14 microU/mL) also were reduced. In contrast, serum [125I]IGF-I binding activity was markedly increased in SGA litters compared to sham (65 +/- 5% maximum binding with 2.5 microL/mL SGA serum vs 14 +/- 3% for sham serum, p less than .001), and correlated with fetal weight (r = -0.539, p less than .05) and insulin (r = -0.622, p less than .05). Ligand blotting with [125I]IGF-I revealed that serum levels of IGFBP-1 (32 K) were greater in SGA than shams, while immunoblotting with specific antiserum demonstrated that levels of IGFBP-2 (34 K), the major fetal rat IGF BP, were similar in serum from SGA and shams litters. Affinity labeling and immunoprecipitation confirmed that IGF binding activity is increased in SGA, due largely to increased availability of IGFBP-1. In addition, Northern analysis of hepatic RNA revealed that the abundance of IGFBP-1 mRNA is increased in the SGA fetal rat, while hepatic mRNA for IGFBP-2 is similar in SGA and sham-operated litters. We conclude that circulating levels of IGFBP-1 and the abundance of hepatic mRNA are increased in the SGA fetal rat. IGFBP-1 may be an important modulator of IGF bioactivity and somatic growth in utero.

Production of the rat type 1 insulin-like growth factor-binding protein by well differentiated H4EIIC3 hepatoma cells: identification, purification, and N-terminal amino acid analysis.

We recently identified a 32 K mol wt insulin-like growth factor (IGF)-binding protein (BP) which is markedly increased in the serum of streptozotocin-diabetic rats and recognized by antiserum against the human amniotic fluid IGFBP (hIGFBP-1). In the present study we sought to confirm that this protein represents the rat homolog of IGFBP-1 (rIGFBP-1), and that rIGFBP-1 may, therefore, play an important role in the regulation of IGF bioactivity in experimental diabetes. Since the abundance of related hepatic mRNA is high in diabetic rats, we asked whether well differentiated H4EIIC3 rat hepatoma cells produce rIGFBP-1 and provide sufficient amounts of this protein for purification and further characterization. Specific IGF-binding activity in hepatoma conditioned medium was detected initially by incubation with 125I-labeled recombinant human IGF-II and precipitation with polyethylene glycol. Ligand blotting demonstrated a 32 K BP, identical in size to the major low mol wt IGFBP found in diabetic rat serum. Affinity labeling and immunoprecipitation confirmed that this BP is related to human IGFBP-1 and is distinct from the fetal rat IGFBP, rIGFBP-2. Incorporation of [35S]methionine into 32 K BPs confirmed synthesis by hepatoma cells. For purification of BPs, conditioned medium was collected in roller culture, and BPs were purified by ammonium sulfate precipitation, Sephadex G-75 chromatography, and reverse phase HPLC. Partial amino acid sequencing of purified protein demonstrated 68% identity with the human IGFBP-1 and distinguished this BP from previously characterized rat IGFBPs. Purified protein bound both IGF-I and IGF-II with high affinity. We conclude that the 32 K IGFBP produced by H4EIIC3 hepatoma cells in culture represents the rat form of IGFBP-1 (rIGFBP-1). Regulation of rIGFBP-1 may play an important role in the modulation of IGF bioactivity in experimental animals with metabolic disease. The availability of purified rIGFBP-1 and identification of a cell line that produces this BP will greatly facilitate future studies of IGFBP-1 in the rat model.