Robert G. Stern

High-resolution computed tomographic bronchiolography using perfluoroctylbromide (PFOB): an experimental model.

The use of perfluoroctylbromide (PFOB), a liquid ventilatory agent, was evaluated as a computed tomographic contrast agent to visualize small airway anatomy to the level of the centrilobular bronchiole, normally not visible on high-resolution computed tomography (HRCT). A freshly excised neonatal lamb heart-lung preparation was tracheally intubated, suspended in a saline bath, and mechanically ventilated with gas. After obtaining HRCT control images with suspended respiration using continuous positive airway pressure, 30 ml of perfluoroctylbromide was instilled into the trachea and repeat scans were obtained. These images demonstrated PFOB filling and distending the airways to the level of the centrilobular bronchioles and their first order branches. There was only minimal spillage into air spaces, allowing excellent anatomic detail of the bronchiolar structures. A liquid ventilatory agent, PFOB is a superb candidate as a bronchographic contrast agent due to its promotion of gas exchange, low toxicity, low surface tension, radiopacity, and vaporized excretion via the lung. It has great potential to evaluate small airway disease when used in conjunction with HRCT.

Virtual bronchoscopy with perfluoronated hydrocarbon enhancement

RATIONALE AND OBJECTIVES Bronchoscopic computed tomography (CT) is limited by machine resolution and air-soft-tissue contrast. The objective of this study was to determine whether improving the contrast by using the contrast agent perflubron (PFOB) in the lung would improve the bronchoscopic CT technique and permit visualization of small airways. MATERIALS AND METHODS Bronchoscopic CT was performed in an anesthetized 8-week-old New Zealand white rabbit before and after the endotracheal administration of PFOB. RESULTS Bronchoscopic CT performed with PFOB permitted navigation of bronchi as small as 0.8 mm in diameter, which are much smaller than those that can be navigated without PFOB. CONCLUSION In this example, the use of perfluorochemicals with bronchoscopic CT enhanced the capabilities of virtual bronchoscopy.

The Consumption Gene

After years of pondering the over-testing, over-imaging, over-diagnosis, and over-treatment that typify US medicine, I have concluded that, like everything else, it must be genetic: We have evolved a gene that controls (or rather, disinhibits) consumption in all its forms. Although the gene has yet to be identified, I think it should be designated as GETIT. The phenotype manifests as overconsumption of EVERYTHING: food, cars, housing, entertainment, appliances, energy drinks, dietary supplements. Of course, we no longer make most of these things; but we do massively produce health care: We’ve reached around 18% of the US gross domestic product (GDP) already and are projected to reach one fifth of GDP by 2021. The gene may still be hidden, but clearly it has to be there. This genetic driver has powerfully affected medicine. First, let’s pick on the patients, always a fun thing to do. Clearly, Americans LOVE consuming medical care. The statistics do not lie: Americans consume more health care per capita than any country in the world. Yet, the US leads the world in no other measure of health, suggesting that it is the act of consumption, rather than the medical benefit, that drives the process. Physicians every day face patients with viral upper respiratory infections demanding antibiotics, with headaches or back pain demanding magnetic resonance imaging (MRI) and narcotics, with upset stomachs demanding computed tomography . Of course, most physicians know that the overwhelming majority of these patients have self-limited diseases. But they also know that if their demands are not met, the patients will simply go to someone else. What’s a doc to do? But a lot of us medical practitioners have the same mutation. Why should we be different? And if you want to consume, you gotta have the money, so medical bloat turns out to be a good thing. Of course, it’s a bit more complex than that—I don’t mean to say that all docs are

Ordering high-cost medical imaging: a right or a privilege?

Imagine for a moment, a medical system composed of 3 groups of clinicians. One group has a high level of understanding of most high-cost imaging studies and generally orders studies appropriately. The second group has a pretty good understanding of some types of high-cost imaging studies but has serious gaps in knowledge regarding the appropriateness of some types of examinations, including those outside its area of clinical expertise. The third group is essentially clueless about what high-cost imaging studies can and cannot show and is incompetent in ordering them. Now imagine that the society in which these clinicians and their patients live is being financially crushed by the costs of medical care. Imagine further that in this society anyone with a medical degree has an inherent right to order any test, regardless of cost and whether it makes any clinical sense. A physician can order hundreds of useless computed tomography, magnetic resonance, ultrasound, or nuclear medicine studies without ever being asked to provide a rationale for them or even guess at their likely utility. In this imaginary system, the clueless physician has the same right to order as the competent physician. Just imagine. Consider how this differs from other aspects of medicine: Physicians, at least in hospitals, are required to demonstrate competence before being allowed (or granted privileges) to perform their duties, be they procedures, surgeries, consultations, or interpretations of electrocardiograms, laboratory studies, pulmonary function testing, vascular laboratory examinations, or even imaging studies themselves. But in this imaginary society, there is no need for any mechanisms to identify or rectify abuse of imaging studies. No need to show competence before being allowed to order multi-thousand dollar exams. No need to track any misuse of technology. No need to see which patients are being overtreated, over-radiated, overtaxed, or indeed, overcharged. Just not that important. And nobody would be rude enough to suggest that these clinicians might not be experts in highly specialized imaging options and could benefit from input from other, more knowledgeable

The incidental solitary pulmonary nodule: algorithms, options, and patient choice.

Many physicians love algorithms. They provide structure, clarify clinical reasoning, organize thought processes, and are easy to memorize. On occasion, they provide defensive cover for quality of care, essentially “proving” that one has done things the proper way. I particularly like the ones that rhyme. Imaging algorithms are common and quite useful in a variety of clinical settings, including screening, diagnostics, and therapy evaluations. Pick a disease or clinical finding, and I can show you an algorithm on almost anything— which study to do, at what interval, and in what sequence. They are important and powerful. But without clinical and philosophic context, algorithms can lead down paths one would like to avoid, and waste a lot of time, money, and emotional stress for patient and physician alike. This editorial focuses on the incidental solitary pulmonary nodule, but is applicable to other entities. My intent is not to reiterate already well-established imaging algorithms for pulmonary nodules incidentally noted on chest x-rays or computed tomography (CT) scans obtained for other reasons (see Fleischner Society recommendations). Rather, I would like to focus on the need for flexibility in algorithmic clinical imaging, which reflects a thoughtful and deliberate process that can lead to considerable variations in actual imaging studies performed and depends on patient and physician choices appropriately applied to algorithms. Sometimes we lose sight of the fact that algorithms are really meant for guidance, not dogmatic clinical directives.

Virtual Bronchoscopy with Perflubron Enhancement. |[dagger]| 1814

The advent of helical computerized tomography (CT) has allowed for volumetric data acquisition with markedly improved multiplanar reconstruction as well as three dimensional rendering. Post-processing software has permitted changing the viewer frame of reference thus allowing direct visualization of the inside of large airways or so called virtual bronchoscopy. Air within the lumen supplies contrast; however, in bronchial tree branches, the walls are thin thereby reducing contrast and resolution. We hypothesized that the instillation of a dose of liquid perflubron (LiquiVent®, Alliance Pharm Corp, San Diego, CA) would increase airway contrast and therefore increase airway resolution. To test this hypothesis, we compared helical CT images in an anesthetized, intubated, adolescent New Zealand rabbit model during mechanical gas ventilation at end inspiration and expiration. Imaging was performed without and with 15 ml/kg of perflubron in the lungs. A Picker PQ 5000 helical CT scanner was used and targeted 10 cm FOV, 3mm slice thickness, with a pitch of 1.25, images reconstructed every 3mm with a smooth spatial reconstruction algorithm, and mA/kVp of 200/120. The bronchoscopic CT without perflubron only allowed visualization of the first 2 generations with poor resolution of 3rd order branches and beyond. In contrast, images with perflubron permitted improved resolution of the tracheobronchial tree to the 5th order branches. These preliminary studies demonstrate that perflubron liquid in the lungs can enhance bronchoscopic CT images of the tracheobronchial tree by improving contrast and resolution of more distal generations of airways. This new innovation represents a potentially favorable combination of perfluorochemicals as contrast medium with the emerging technology of virtual bronchoscopy. (Perflubron provided by Alliance Pharm Corp & Hoechst Marion Roussel)