John C. Wandtke

Computerized search of chest radiographs for nodules.

A computer program that recognizes potential pulmonary nodules in PA chest radiographs has been developed. This program produces a display of candidate nodules that require interpretation by a radiologist. Some false positives are rejected by a program, the Nodule Expert. Detection performance with and without Nodule Expert has been evaluated. Using the untrained program (no Nodule Expert), and after inspecting 45 candidate nodules, a radiologist may be confident that a nodule was inspected, if one was located by the program. When pattern recognition techniques are incorporated, the number of false positives presented for inspection is reduced. The radiologist must inspect, at most, 10 candidate nodules to be confident of having inspected a nodule, if one was located by the program. Concomitant with this decrease in the candidate nodule false-positive rate is a decrease in sensitivity (film true-positive rate) from 92 to 86%. This program was trained on candidate nodules from 37 radiographs and also tested on these 37. Some of the features used by the pattern classifier to classify candidate nodules are comparable to those used by human observers.

Measurement of Lung Gas Volume and Regional Density by Computed Tomography in Dogs

To determine if computed tomography (CT) can accurately measure lung volume, we compared lung gas volume measured by helium dilution with the equivalent volume calculated from CT total lung volume and density in 13 supine dogs. CT lung gas volume underestimated helium volume by 34% (range: -63 to 0%). Studies of wooden lung phantoms varying in density from 0.082g/cc to 0.776g/cc showed that only 15% of this error could be mimicked by the phantoms. The rest of the discrepancy is attributed to the lungs irregular borders, and the sharp density gradients surrounding and within the lung that result in x-ray beam hardening, sampling limitations, and partial volume measurement errors. Serial biweekly measurements in three dogs for 14 weeks showed CT gas volume to be highly reproducible with less scatter than seen in the helium measurements. Density in the lungs of all dogs showed a uniform gradual decrease from approximately 0.60g/cc at the dependent surface to 0.20g/cc at the superior surface with relatively constant density at any horizontal level. These studies show that whereas CT underestimates gas volume in the lungs, serial measurements are highly reproducible in experimental studies and are a promising technique to monitor diseases or response to therapy. Density gradients in the lungs were sufficiently uniform so that disruption of the normal gradient may be an indicator of early lung disease.

Malignant solitary fibrous tumor: report of 3 cases with unusual features.

Malignant solitary fibrous tumor (MSFT) is a rare neoplasm. Three cases of MSFT with unusual features, including 1 pleural and 2 extrapleural, are reported. A 64-year-old woman with a large right thoracic MSFT and episodes of severe hypoglycemia experienced resolution of her hypoglycemia immediately after resection of the MSFT. A 27-year-old woman with primary retroperitoneal MSFT had pulmonary metastases 10 months after resection of the primary tumor. A 54-year-old man with an intracranial solitary fibrous tumor suffered from multiple pulmonary metastases and local recurrence 21 and 28 months after resection of the primary tumor, respectively. All 3 cases of solitary fibrous tumor displayed malignant features. The tumor cells in each case were positive for CD34 and Bcl-2, but negative for cytokeratin, smooth muscle actin, S-100, and c-kit. In addition, the tumor cells in the case with concomitant hypoglycemia were strongly positive for insulin-like growth factor-II. The histopathologic diagnostic criteria for MSFT, the differential diagnosis with other spindle cell tumors, and the mechanism of MSFT-derived hypoglycemia via insulin-like growth factor-II are discussed.

Stress fracture of the tibia : An unusual complication of reconstructive surgery of the mandible

The oral and maxillofacial surgeon is frequently involved in reconstructive surgery of the maxillofacial region for congenital dentofacial anomalies, trauma, and oral cavity tumors. In such treatments, autografting with a vascularized fibula has improved the ability to reconstruct continuation defects of the mandible. Morbidity at the donor site is infrequent and has mostly been related to decreased muscle strength and gait changes. l-3 Stress fractures of the tibia unrelated to graft harvesting are not uncommon and usually occur in athletes or military recruits during strenuous activity.*l’ Stress fractures of the tibia after harvesting a fibular graft are uncommon with two articles1*,13 reporting a total of six cases. Five of these occurred in nonvascularized grafts,12 and only one case has been reported in conjunction with a vascular fibular graft.‘3 We report a patient who had mandibular reconstruction with a vascularized fibular graft who developed a stress fracture of the tibia.

Looking beyond the thrombus: essentials of pulmonary artery imaging on CT.

AbstractBackgroundPulmonary arteries are not just affected by thrombus. Congenital and acquired conditions can also involve the pulmonary arteries. An awareness of these conditions is important for the radiologist interpreting chest computed tomography (CT).MethodsThe anatomy of the pulmonary arteries was reviewed. CT and magnetic resonance (MR) acquisition protocols for imaging the pulmonary arteries were discussed. The imaging appearances of congenital and acquired anomalies involving the pulmonary arteries, using CT and other modalities, were presented.ResultsImaging features of congenital anomalies presented include pulmonary agenesis, partial pulmonary artery agenesis, patent ductus arteriosus, pulmonary artery sling, congenital pulmonary artery stenosis and coronary to pulmonary artery fistula. Acquired pulmonary artery anomalies discussed include arteritis, infected aneurysm and sarcoma. Pulmonary artery filling defects besides thromboembolism are also discussed, including foreign body emboli. Imaging features of bronchogenic carcinoma and mediastinal fibrosis demonstrating compression of the pulmonary arteries are presented, followed by a brief discussion of post repair appearance of the pulmonary arteries for congenital heart disease.ConclusionsCongenital and acquired pulmonary artery anomalies have a characteristic appearance on a variety of imaging modalities. An acquaintance with the imaging features of these anomalies is needed to avoid misinterpretation and reach the correct diagnosis. Teaching Points • Discuss a variety of congenital and acquired anomalies of the pulmonary arteries.• Discuss the imaging appearance of the presented congenital or acquired pulmonary artery anomalies.• Describe CT and MR acquisition protocols for imaging the pulmonary arteries.• Review the anatomy of the pulmonary arteries.

Integration, acceptance testing, and clinical operation of the Medical Information, Communication and Archive System, phase II

The Medical Information, Communication and Archive System (MICAS) is a multivendor incremental approach to picture archiving and communications system (PACS). It is a multimodality integrated image management system that is seamlessly integrated with the radiology information system (RIS). Phase II enhancements of MICAS include a permanent archive, automated workflow, study caches, Microsoft (Redmond, WA) Windows NT diagnostic workstations with all components adhering to Digital Information Communications in Medicine (DICOM) standards. MICAS is designed as an enterprise-wide PACS to provide images and reports throughout the Strong Health healthcare network. Phase II includes the addition of a Cemax-Icon (Fremont, CA) archive, PACS broker (Mitra, Waterloo, Canada), an interface (IDX PACSlink, Burlington, VT) to the RIS (IDXrad) plus the conversion of the UNIX-based redundant array of inexpensive disks (RAID) 5 temporary archives in phase I to NT-based RAID 0 DICOM modality-specific study caches (ImageLabs, Bedford, MA). The phase I acquisition engines and workflow management software was uninstalled and the Cemax archive manager (AM) assumed these functions. The existing ImageLabs UNIX-based viewing software was enhanced and converted to an NT-based DICOM viewer. Installation of phase II hardware and software and integration with existing components began in July 1998. Phase II of MICAS demonstrates that a multivendor open-system incremental approach to PACS is feasible, cost-effective, and has significant advantages over a single-vendor implementation.

Newer imaging methods in chest radiography

In recent years the application of computers to chest radiography has resulted in a wide variety of innovative research. Major research efforts have resulted in the development of new types of x-ray detectors, such as storage phosphor technology, for use with computers. Storage phosphor imaging is one of the most promising new techniques, and almost 100 systems have been installed worldwide. Radiologists are quickly evaluating the image quality provided by this new detector system, which has the potential to improve image quality. It has wide latitude and is coupled with a computer to perform image processing. Another promising technology, originally studied in the form of scan equalization radiography, is now commercially available in the form of advanced multiple-beam equalization radiography. This film technique uses computers to modulate the x-ray exposure to take maximum advantage of the imaging capabilities of radiographic film. Digital solid-state detectors have been studied in conjunction with computerized image enhancement systems. These currently show improvement in nodule detection and quantification of the calcium content of a lesion. Application of large image intensifiers to a digital image system is being studied, but there are currently limitations on spatial resolution.

Medical information, communication, and archiving system (MICAS): Phase II integration and acceptance testing

The Medical Information, Communication and Archive System (MICAS) is a multi-modality integrated image management system that is seamlessly integrated with the Radiology Information System (RIS). This project was initiated in the summer of 1995 with the first phase being installed during the first half of 1997 and the second phase installed during the summer of 1998. Phase II enhancements include a permanent archive, automated workflow including modality worklist, study caches, NT diagnostic workstations with all components adhering to Digital Imaging and Communications in Medicine (DICOM) standards. This multi-vendor phased approach to PACS implementation is designed as an enterprise-wide PACS to provide images and reports throughout our healthcare network. MICAS demonstrates that aa multi-vendor open system phased approach to PACS is feasible, cost-effective, and has significant advantages over a single vendor implementation.

Imaging Features of Chest Wall Tumors

The differential diagnosis of chest wall tumors is diverse, including both benign and malignant lesions, and local extension of adjacent disease. Chest wall tumors can arise from the soft tissue and osseous structures of the thorax, which include the ribs, cartilage, nerves, muscles, fat, and lymph nodes. As most chest wall tumors are amenable to biopsy, the initial role of chest radiography is to localize a lesion to the chest wall and to reduce the need for biopsy of benign tumors. Advanced imaging, including CT or MRI, can be used to further evaluate tumor margins, soft tissue involvement, and degree of bony or spinal cord invasion. Techniques to localize and characterize chest wall tumors and a detailed differential diagnosis will be discussed.

The strategic and operational characteristics of a distributed phased archive for a multivendor incremental implementation of picture archiving and communications systems

The long-term (10 years) multimodality distributed phased archive for the Medical Information, Communication and Archive System (MICAS) is being implemented in three phases. The selection process took approximately 10 months. Based on the mandatory archive attributes and desirable features, Cemax-Icon (Fremont, CA) was selected as the vendor. The archive provides for an open-solution allowing incorporation of leading edge, “best of breed” hardware and software and provides maximum flexibility and automation of workflow both within and outside of radiology. The solution selected is media-independent, provides expandable storage capacity, and will provide redundancy and fault tolerance in phase II at minimum cost. Other attributes of the archive include scalable archive strategy, virtual image database with global query, and an object-oriented database. The archive is seamlessly integrated with the radiology information system (RIS) and provides automated fetching and routing, automated study reconciliation using modality worklist manager, clinical reports available at any Digital Imaging and Communications in Medicine (DICOM) workstation, and studies available for interpretation whether validated or not. Within 24 hours after a new study is acquired, four copies will reside within different components of the archive including a copy that can be stored off-site. Phase II of the archive will be installed during 1999 and will include a second Cemax-Icon archive and database using archive manager (AM) Version 4.0 in a second computer room.