Certified reference materials for radionuclides in Bikini Atoll sediment (IAEA-410) and Pacific Ocean sediment (IAEA-412).

The preparation and characterization of certified reference materials (CRMs) for radionuclide content in sediments collected offshore of Bikini Atoll (IAEA-410) and in the open northwest Pacific Ocean (IAEA-412) are described and the results of the certification process are presented. The certified radionuclides include: (40)K, (210)Pb ((210)Po), (226)Ra, (228)Ra, (228)Th, (232)Th, (234)U, (238)U, (239)Pu, (239+240)Pu and (241)Am for IAEA-410 and (40)K, (137)Cs, (210)Pb ((210)Po), (226)Ra, (228)Ra, (228)Th, (232)Th, (235)U, (238)U, (239)Pu, (240)Pu and (239+240)Pu for IAEA-412. The CRMs can be used for quality assurance and quality control purposes in the analysis of radionuclides in sediments, for development and validation of analytical methods and for staff training.

Certified Reference Material IAEA-446 for radionuclides in Baltic Sea seaweed.

A Certified Reference Material (CRM) for radionuclides in seaweed (Fucus vesiculosus) from the Baltic Sea (IAEA-446) is described and the results of the certification process are presented. The (40)K, (137)Cs, (234)U and (239+240)Pu radionuclides were certified for this material, and information values for 12 other radionuclides ((90)Sr, (99)Tc, (210)Pb ((210)Po), (226)Ra, (228)Ra, (228)Th, (230)Th, (232)Th, (235)U, (238)U, (239)Pu and (240)Pu) are presented. The CRM can be used for Quality Assurance/Quality Control of analysis of radionuclides in seaweed and other biota samples, as well as for development and validation of analytical methods, and for training purposes.

A new Certified Reference Material for radionuclides in Irish sea sediment (IAEA-385).

A new Certified Reference Material (CRM) for radionuclides in sediment (IAEA-385) is described and the results of the certification process are presented. Eleven radionuclides ((40)K, (137)Cs, (226)Ra, (228)Ra, (230)Th, (232)Th, (234)U, (238)U, (238)Pu, (239+240)Pu and (241)Am) have been certified and information mass activities with 95% confidence intervals are given for seven other radionuclides ((90)Sr, (210)Pb((210)Po), (235)U, (239)Pu, (240)Pu and (241)Pu). Results for less frequently reported radionuclides ((60)Co, (99)Tc, (134)Cs, (155)Eu, (224)Ra and (239)Np) and information on some activity and mass ratios are also reported. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in sediment samples, for the development and validation of analytical methods and for training purposes.

Pulmonary venoocclusive disease: CT findings in eight patients.

OBJECTIVE: The objective of the study was to describe the CT findings of pulmonary venoocclusive disease. MATERIALS AND METHODS: Eight patients with CT scans of the thorax and a diagnosis of pulmonary venoocclusive disease were identified from three institutions. The six males and two females had a mean age of 32 years old (range, 5-58 years old). All scans were evaluated with consensus reading by two chest radiologists. Lung parenchyma were assessed for the type and distribution of disease. Bronchi, pleura, hila, mediastina, and chest walls were evaluated for abnormalities. Pathologic specimens from five patients were reviewed and specifically correlated with the radiologic findings. RESULTS: Seven of the eight patients had interlobular septal thickening. All eight patients had regions of ground-glass opacity. Four of the eight patients had a mosaic pattern of lung attenuation. No enlarged hilar or mediastinal nodes were revealed. Five patients had bilateral pleural effusions. CONCLUSION: The most common CT findings in these eight patients with pulmonary venoocclusive disease were smooth interlobular septal thickening, diffuse multifocal regions of ground-glass opacity, pleural effusions, enlarged central pulmonary arteries, and pulmonary veins of normal caliber. Four patients had a mosaic pattern of lung attenuation on the CT scans. These findings are highly suggestive of pulmonary venoocclusive disease and may be helpful in difficult cases. Definitive diagnosis requires lung biopsy.

"Incisura" of the ascending aorta and vascular pedicle width in the cardiac transplant patient.

BACKGROUND: The purpose of this study was to evaluate three findings in cardiac transplant patients: the appearance, etiology, and incidence of "incisura" (a characteristic indentation) of the ascending aorta; the vascular pedicle width, which usually appears enlarged on standard chest radiographs; and clearing of the retrosternal clear space. MATERIAL: Two hundred sixty-one cardiac transplantations were performed at the University of Minnesota before December 31, 1992. The appearance, etiology, and incidence of an incisura were studied; the vascular pedicle width was measured; and the rate of clearing of the retrosternal clear space was determined. RESULTS: Forty-six percent of the patients whose ascending aorta could be visualized on the lateral chest radiogram showed an incisura. Approximately one third of the patients showed continued opacification of the retrosternal space postoperatively. The width of the vascular pedicle in this series of cardiac transplant patients measured 60.9 +/- 22.8 mm (standard deviation, 11.4 mm), in comparison to a normal of 48 +/- 5.0 mm. CONCLUSIONS: An incisura of the ascending aorta and the widened vascular pedicle are normal postoperative chest radiographic findings in cardiac transplant patients and should not be misconstrued as abnormalities.

Computed tomography correlation in atypical (peripheral) right upper lobe collapse: the minor fissure as an explanation for the pleural-based density.

Peripheral right upper lobe collapse describes the unusual plain film finding in which the collapsed lobe simulates a peripheral, pleural-based mass. Most investigators have postulated that the peripheral opacity is explained by the interface between the superior segment of the lower lobe and the posterior aspect of the collapsed upper lobe, which does not swing as far medial as in the normal pattern of collapse. In our patient, using computed tomography (CT) correlation, we demonstrated that the finding is explained by the interface between the middle lobe and the anterior aspect of the collapsed upper lobe.

Imaging of small airways disease.

High-resolution computed tomography (HRCT) is the most useful modality for imaging of small airways disease. Direct signs of small airways disease that appear on HRCT scans are the result of changes in the airway wall or lumen. Abnormal small airways can be seen as tubular, nodular, or branching linear structures on HRCT scans. Indirect signs of small airways disease result from changes in the lung parenchyma distal to the diseased small airway and include air trapping, subsegmental atelectasis, centrilobular emphysema, and air-space nodules. Diverse inflammatory and infectious processes, such as bronchiolitis obliterans (BO), bronchiolitis obliterans with organizing pneumonia (BOOP), smoking-related diseases, and asthma affect the small airways of the lungs. HRCT findings of BO include air trapping and bronchiectasis. The predominant findings of BOOP are consolidation and ground-glass attenuation. HRCT can show abnormalities such as small nodules and areas of ground-glass attenuation even in asymptomatic smokers, but emphysema predominates in smokers with moderate or severe obstructive disease. Patients with asthma can have thickened airway walls, plugged large and small airways, subsegmental atelectasis, and air trapping, but emphysema is rarely seen even in severe asthma patients. HRCT scans can often accurately depict disease processes in the small airways and can occasionally lead to a specific diagnosis from among several clinically relevant possibilities.

Axial and lateral resolution of rotational intravascular ultrasound: in vitro observations and diagnostic implications.

PURPOSE: To determine the axial and lateral resolution of a rotating intravascular ultrasound system and the diagnostic implications for the diagnosis of early artherosclerosis. METHODS: The resolution of a 20 MHz rotating transducer was tested in a specially designed high-resolution phantom and in five aortic autopsy specimens with varying degrees of early atherosclerosis. RESULTS: The best lateral resolution is at the minimal distance between transducer and object. Measurements in the wire phantom showed this to be better than 0.43 mm. This is less than the axial resolution which is better than 0.13 mm. Decreasing lateral resolution with increasing distance between transducer and object is manifested by arcing and overestimation of the extent of focal atherosclerotic lesions. CONCLUSION: Axial resolution is significantly better than lateral resolution. Rapid deterioration of lateral resolution affects the diagnostic ability to characterize the extent of early atherosclerosis. Eccentric positioning of the transducer tip, particularly in larger vessels, will therefore influence diagnostic accuracy in vivo.

Heart-lung and lung transplantation.

Lung and heart-lung transplantation have evolved into successful therapeutic options in patients with end-stage cardiopulmonary disease. Imaging studies extend from pretransplant evaluation to posttransplant monitoring for complications. Although many radiologic features are considered nonspecific, improved understanding of underlying pathologic and physiologic conditions unique to this population will enhance the clinical impact of the radiologist involved in a transplantation program.

Regional alterations in lung ventilation in end-stage primary pulmonary hypertension: correlation between CT and scintigraphy.

OBJECTIVE: The purpose of this study was to correlate scintigraphic findings of regional alterations in lung ventilation and perfusion with regional variations in CT attenuation in patients with primary pulmonary hypertension. SUBJECTS AND METHODS: Chest CT scans and ventilation-perfusion scans obtained within 24 hr of each other in 18 patients with primary pulmonary hypertension referred for lung transplantation were reviewed. The lungs were divided into eight regions (left/right, superior/inferior relative to the carina, and anterior/posterior relative to the trachea). CT scans were evaluated and areas of parenchymal inhomogeneities were tabulated for the eight regions. Areas of reverse mismatch (perfusion without ventilation) were established by blinded analysis of planar scintigraphic studies in six projections using 99mTc-labeled DTPA-aerosol and macroaggregated albumin for the eight regions and then were correlated with the CT findings. RESULTS: Abnormal findings on ventilation scans and reverse ventilation-perfusion mismatches indicating an inadequate hypoxic vasoconstriction reflex were found in 91 regions in all 18 patients. Nonuniform parenchymal CT density was found in 12 patients. There was a significant correlation (p = .009) of scintigraphic reverse mismatches with abnormal CT density in 38 regions in 11 patients. In one patient, there was no scintigraphic correlation with abnormal CT attenuation. The specificity of abnormal CT density for scintigraphic reverse mismatches was 81%, with a sensitivity of 42%. CONCLUSION: Scintigraphic reverse mismatches indicate a high prevalence of significant pulmonary arterial shunting in patients with ventilatory defects. Increased relative CT attenuation in areas of impaired ventilation as shown on the ventilation scans is amplified in primary pulmonary hypertension by an inadequate hypoxic vasoconstriction reflex. This finding does not signify underlying infiltrative lung disease and correlates with regions with reverse mismatches.

Pectus excavatum: abnormal exercise scintigraphy with normal coronary arteries.

Pectus excavatum is the most common congenital abnormality of the chest wall, and is frequently associated with chest pain. The invasive, as well as the ECG and echocardiographic assessment of possible coronary artery disease (CAD) in adults with moderate to severe forms of this deformity, is often complicated by the associated displacement of the heart in the chest cavity in these patients. We present findings in a 67-yr-old male that demonstrate that the predictive accuracy of positive stress radionuclide ventriculogram (RVG) and SPECT scintigraphic studies may be significantly reduced in patients with moderate to severe forms of this abnormality. Our findings also suggest, however, that either lateral or even a shallow left posterior oblique detector positioning during RVG, a significantly revised SPECT acquisition orbit, or planar imaging may provide a more accurate means to assess possible CAD in these patients. Like-wise, physician input would appear to be invaluable in determining the optimal mode of imaging and the acquisition protocol for patients with pectus excavatum.

Volumetric high-resolution CT in the diagnosis of interstitial lung disease and bronchiectasis: diagnostic accuracy and radiation dose.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic accuracy and radiation dose of volumetric high-resolution CT in the diagnosis of interstitial lung disease and bronchiectasis when four contiguous sections were acquired at each of three levels. The potential benefits were weighed against the increased radiation dose of multiple scans. SUBJECTS AND METHODS: High-resolution CT scans of four contiguous sections were obtained at each of three locations (the aortic arch, the carina, and 2 cm above the diaphragm) in 50 consecutive patients (mean age, 44 years old) with known or suspected interstitial lung disease or bronchiectasis who were referred for evaluation with high-resolution CT. Each individual scan was analyzed for the presence of motion-induced streaking, blurring, or doubling. The diagnostic information contained in each set of four scans was compared with that contained in the first of the four scans in the set. RESULTS: Motion degraded at least one of the four images in each set in 69 (46%) of 150 volumetric acquisitions. When the full set of four images was considered instead of just the first scan from the set, the number of motion-free studies in patients with suboptimal respiratory suspension was increased by 40% (from 99 to 139). Diagnostic accuracy was improved as more features were identified on contiguous scans: the sensitivity of the first scan compared with that of the complete set of four scans was 84% for the detection of bronchiectasis, 97% for ground-glass opacity, 88% for honeycombing, 88% for septal thickening, and 86% for nodular opacities. Although the integral radiation exposure for a set of four CT scans was 2.8 times that of a single scan obtained with standard technique, peak skin exposure was unchanged. Slightly increased image noise with the reduced technique compromised diagnostic ability in 6% of studies. CONCLUSION: The use of volumetric high-resolution CT increased diagnostic accuracy, particularly for bronchiectasis at the lung bases, without increasing peak skin radiation exposure. With the availability of four contiguous scans per anatomic level, the subjective confidence in interpretation and number of motion-free studies also increased.

Alternative design for radiologic guidance in video thoracoscopic surgery.

RATIONALE AND OBJECTIVES: Easy dislodgment and a pneumothorax rate of up to 50% have been reported with the use of mammographic hookwires for radiologic guidance in thoracoscopic surgery. An alternative design is described and preliminary in vitro results are reported. METHODS: The new design is based on the T-fastener used in percutaneous gastrostomies and can be deposited with a 20-Fr guidance needle. In vitro measurements of the anchoring capability of this design were compared with the anchoring capability of the Hawkin's III (Meditech/Boston Scientific, Watertown, MA) mammographic hook wire system. RESULTS: Anchoring capabilities of the alternative anchoring design and the Hawkin's III mammographic hook wire localization system are comparable. Complete dislodgement of both anchors occurs at approximately 350 gm. CONCLUSIONS: Preliminary in vitro investigation demonstrated similar anchoring capabilities of the new design and mammographic hook wires. Potential advantages of this suture-based localization device over hook wires are discussed.

Ground-glass opacity of the lung parenchyma: a guide to analysis with high-resolution CT.

Ground-glass opacity is a frequent but nonspecific finding on high-resolution CT scans of the lung parenchyma. The underlying abnormality is diverse; any condition that decreases the air content of the lung parenchyma without totally obliterating the alveoli can produce ground-glass opacity. These processes are not visible on high-resolution CT scans. However, in specific clinical settings, the information provided by high-resolution CT is considerable when the anatomic distribution and associated structural changes to the lung parenchyma are analyzed. This pictorial essay illustrates the pathologic basis of ground-glass opacity and provides a guide to the differential diagnosis of the disorders that can produce this appearance.

Shifting pneumothorax after heart-lung transplantation.

Heart-lung transplantation involves the total replacement of two of the most complex organs of the thoracic cavity. This procedure is usually reserved for patients with failure of both systems, such as in primary pulmonary hypertension or chronic Eisenmenger physiology. The en bloc replacement of the heart and lungs leaves an open communication between the two sides of the thorax that may allow air or fluid to shift from one side to the other. To evaluate this possibility, the authors reviewed the chest radiographs of 25 heart-lung transplant recipients for signs of rapidly changing pneumothoraces that could not be explained by the conventional dynamics of pleural physiology. A series of postoperative radiographs showed unusual shifting or apparently rapid disappearance of pneumothoraces in eight patients. Decompression of a pneumothorax with a contralateral chest tube was a phenomenon observed in six of these patients.

Preoperative assessment of prostatic carcinoma by computerized tomography. Weaknesses and new perspectives.

A retrospective study of five years' experience with fourth-generation computerized tomography (CT) scan was undertaken to assess the frequency of understaging in prostate cancer. A total of 160 patients with preoperative scans were surgically staged. In 10 patients, the operation was aborted after pelvic node dissection had revealed unsuspected metastatic involvement. Based on the histopathologic evidence of local tumor invasion, extension into seminal vesicles or pelvic lymph nodes, restaging was required in 78 percent of cases. Accuracy was 24 percent for capsular extension, 69 percent for seminal vesicle invasion, and 72 percent for lymphadenopathy. The poor yield of CT scan as a preoperative staging modality is demonstrated. Recent advances in the understanding and management of prostatic cancer require reassessing patient benefit and cost effectiveness of available imaging techniques, focusing on the problem of detecting nodal metastases, and predicting tumor spread to regional lymph nodes by accurately evaluating the primary neoplasm. We conclude that CT scan fails to demonstrate the required precision needed to evaluate local tumor spread; therefore, this goal must be pursued with newer imaging modalities.

Pneumothorax after lung biopsy: prevention with transpleural placement of compressed collagen foam plugs.

The effectiveness of pleural sealing with a compressed collagen foam plug in preventing the development of pneumothorax was evaluated in a prospective, comparative study of 50 patients undergoing transthoracic needle biopsies. The 4-cm-long plug was deposited through the thin-walled guidance needle at the end of the procedure in a position where it would cross both the visceral and the parietal pleura. The prevalence of postbiopsy pneumothorax was 28% (seven of 25 patients) in the control group and 8% (two of 25 patients) in the plug group. In each study group, two patients with pneumothoraces required chest tubes. Although further experience is necessary, the authors conclude that transpleural collagen foam plug placement may be an effective supplement for transthoracic needle biopsies.

Postmortem angiography of catheter-induced pulmonary artery perforation.

A case of pulmonary artery perforation by the placement of a balloon-tipped, flow-directed (Swan-Ganz) catheter, as demonstrated postmortem by angiography and confirmed by conventional autopsy method, is reported. Angiography is an effective adjunctive modality in the postmortem diagnosis and localization of pulmonary artery perforation. In cases of suspected catheter-induced pulmonary artery perforation and death, postmortem angiography may prove useful to the forensic pathologist.