Paula Gould

European radiologists should have specialist training in emergency radiology, just as happens in the U.S., delegates were told at ECR 2010 in Vienna.

The thorny issue of subspecialty training came up during a packed special focus session on imaging the polytrauma patient. In a straw poll conducted by moderator Dr. András Palkó, approximately two-thirds of audience members indicated that radiologists were included in their hospital’s trauma team. However, just a few delegates raised their hands when asked if they had access to training in emergency imaging.

“My generation trained along modalities. This then shifted to training in an organ-based manner and now we speak about abdominal radiologists and chest radiologists. But in the last few years we have recognized that we may want to have a third approach, the diagnosis- or the patient-based approach, and I am speaking here of oncologic imaging and emergency imaging,” said Palkó, a radiologist at the University of Szeged in Hungary. “This may require a kind of subspecialty training not only in the training period for residents, but also in the postgraduate specialization phase.”

The need for dedicated training in emergency imaging was reinforced by Dr. Gerd Schueller, a radiologist at the Medical University of Vienna. When asked directly by the moderator if this type of subspecialty education should be introduced in European hospitals, his answer was an unequivocal “Yes.”

“Of course emergency radiology is a subspecialty. Of course there are specific findings of trauma. A hemangioma of the liver does not look like a hematoma of the liver. We have to learn the differences,” he said. “It is a very important point. Just as we have special training of the lung in Europe lacks consistent emergency radiology subspecialty training radiology, we should have trauma training. This is not taught well in Europe.”

Schueller explained the radiologist’s role when patients present with multiple severe injuries. The polytrauma patient’s condition will be assessed in the first 60 seconds by an anesthesiologist and surgeon, he said. The radiologist on the trauma team then has four minutes to seek out any life-threatening conditions from plain-film x-rays and a focused assessment with sonography in trauma (FAST) scan.

If the patient can be stabilized, he or she may be moved to an adjacent CT unit for whole-body imaging. This can reveal key causes of hypovolemia and hypoventilation, such as pneumothorax, cerebral injury, pericardial tension, and cervical spine fracture. All imaging should be completed within 30 minutes of the patient arriving in the ER.

Dr. Ulrich Linsenmaier, a radiologist at Ludwig Maximilians University in Munich, Germany, set out the different ways CT scans can be provided in the polytrauma setting. Options include installing a CT scanner adjacent to the ER and fitting a moving gantry so the patient need not be lifted. Alternatively, patients can be brought directly to the imaging room when they are first admitted and all workup carried out on the CT table. This is the preferred solution at Ludwig Maximilians.

The outcome for polytrauma patients is much better if they automatically undergo whole-body CT within 30 minutes of admittance rather than allowing doctors to decide who gets CT and who doesn’t, he said.

A FAST ultrasound scan can be completed in 20 seconds, and can be performed using handheld equipment at the scene of the accident or en route to hospital, according to Dr. Etienne Danse, a radiologist at the Catholic University of Louvain in Belgium.

In unstable patients, a finding of free fluid should be enough to send a patient to the angio suite or the operating room for further, invasive, investigation. Stable patients should proceed to CT, regardless of the FAST findings.

“This is the drawback of ultrasound. If there is no free fluid, it doesn’t mean there is nothing to worry about,” he said.

Note: a version of this article appeared in the 2010

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Europe lacks consistent emergency radiology subspecialty training

Would you drink a half-liter of cream? Not the most appealing prospect, but Prof. David Lomas did just that to check the robustness of liver fat as an imaging biomarker and self-experiment.

“Apart from paralyzing my stomach for the first 12 hours, the following day my liver fat went up 4%,” he told delegates at an ECR New Horizons session on biomarkers. “So there is an issue about dynamic range of fat in the liver, and elsewhere in the body. How rapidly does it change? We don’t really know. In fact, we don’t know what the normal level of fat in the liver is, either.”

Measurement of hepatic steatosis, using MR spectroscopy or chemical shift imaging, is one of a number of MRI biomarkers that could be used to investigate abdominal disease, according to Lomas, a professor of clinical MRI at the University of Cambridge in the U.K. He presented four such candidates during his lecture, outlining the biological basis for each and the main methods of analysis, as well as the weight of clinical evidence.

In the case of liver fat measurements, for example, both MRS and chemical shift imaging are robust, well-understood techniques, Lomas said. However, as with many up-and-coming imaging biomarkers, their repeatability is largely unknown. Such measurements are nonetheless likely to become more important, given the redefinition of fatty liver by drug companies as a treatable medical condition, not a normal variant that can be left alone.

MR-based iron measurements, which can indicate the severity of liver and/or heart disease, are now being used in fields outside of radiology. This is a good indication of a technique’s acceptance, he said. Researchers have two methods to choose from when measuring iron concentration: they can either look at the ratio of T2 shortening in the liver and muscle, or measure R2 and R2* directly. Both methods have been validated, but again, repeatability is uncertain.

Diffusion-weighted imaging is another promising MRI biomarker, this time as an early indicator of treatment response. The apparent diffusion coefficient is typically low in solid tumors but is elevated following necrosis, a change that could be measured using diffusion-weighted MRI. The technique is not necessarily straightforward, though. In the liver, for example, respiratory motion makes it difficult to track the tiny movements of water molecules, requiring breath-holds. Eating has also been shown to influence diffusion MRI results, and certain ADC measurements may be sensitive to perfusion.

Lomas described his fourth candidate biomarker, MR elastography, as being challenging. The concept is relatively straightforward: mechanical waves directed through the organ of interest are used to assess the elasticity or stiffness of tissue, and hence identify the presence of fibrotic changes. Early results are promising, but the technique is quite complicated and, at the moment, the technology is not being used at many sites.

“This is not an easy application because you need special hardware and analysis tools,” he said. “And how do you validate this? There aren’t easy ways you can measure stiffness of the liver in vivo except by this technique.”

Prof. Eric Aboagye, director of the Comprehensive Cancer Imaging Centre at Imperial College in London, described a selection of PET molecular biomarkers that are of interest for drug development work and may also have clinical applications. However, as with all new biomarkers, the questions are: Do we measure the imaging endpoint reliably, and is the imaging endpoint reproducible?

He outlined four key biological mechanisms that PET tracers are being developed to target: angiogenesis, hypoxia, cell proliferation, and apoptosis. Imaging biomarkers for these biological targets are advancing, but more validation is needed.

The clinical value of PET biomarkers must also be established, Aboagye said. F-18 MISO and copper-60 ATSM, for example, have both shown promise in hypoxia imaging and could potentially be used to facilitate “dose painting” in radiotherapy. This emerging method of treatment would see hypoxic areas of tissue being blasted with higher doses of radiation in a bid to improve efficacy.

A version of this article appeared in the 2010

Repeatability questions complicate search for imaging biomarkers

The lungs have quite literally been a black hole for MRI for many years. Now advances in hardware and imaging techniques are helping lung MRI move into the clinical arena.

There are several reasons to use MRI for lung studies, Prof. Hans- Ulrich Kauczor, director of diagnostic radiology at the University Hospital in Heidelberg, Germany, told delegates at an ECR New Horizons session. The modality can provide a comprehensive structural and functional assessment of the lungs in a single examination and has the potential to yield quantitative measurements. MRI’s chief advantage, however, over CT is the absence of ionizing radiation.

“No radiation is better than a lot of radiation, and no radiation is also better than low radiation,” said Kauczor, who chaired the session.

Although the first lung MRI studies were conducted in the 1980s, researchers were unable to show any clinical value. The techniques were revived in the 1990s by select groups who explored the idea of hyperpolarized gas imaging, but once again the modality failed to make the transition into clinical practice. Over the past 10 years, however, the development of MR-specific contrast agents and the launch of nextgeneration systems offering parallel imaging have improved the quality of lung MRI.

Will the removal of technological barriers lead to broad clinical acceptance and applications? Kauczor followed this question with a provocative vision: MRI can simplify the current diagnostic workup for patients presenting with suspected pulmonary disease.

“Pulmonary lung function test, lab test, chest x-ray, echo, CT, bronchoscopy, scintigraphy... Why not try to solve all the stuff that is addressed nowadays by four or five imaging techniques with a single imaging technique, namely MRI?” he said.

The wide variety of lung MRI techniques was set out by Dr. Jim Wild, a medical physicist at the University of Sheffield in the U.K. His checklist included standard proton MRI, oxygenenhanced imaging, contrast-enhanced pulmonary angiography, perfusion imaging, and hyperpolarized gas MRI (helium and xenon).

Wild acknowledged that some of the methods he presented would only ever be of value to radiology researchers. Others could make the transition into clinical practice, so long as the methods were simplified.

“Overall, the future looks bright for lung MRI,” he said.

There is definitely light at the end of the tunnel for lung MRI, according to Dr. Jürgen Biederer, a radiologist at the University Hospital in Kiel, Germany. Biederer drew on examples from published literature to show the clinical merits of breath-hold and freebreathing sequences when seeking out neoplasms or evaluating inflammatory lung disease.

In the case of small nodular lesions, for example, MRI was shown to rival CT in terms of sensitivity. CT can detect 65% to 85% of nodules sized between 5 mm and 10 mm in diameter. Depending on the sequence, MRI has a sensitivity of ~75% to ~90% for 3 to 5-mm nodules, rising to ~95% to ~100% for 6 to 10-mm nodules.

“It is easier to read lung nodules on MRI than CT because they really stand out on a black background,” Biederer said.

Lesion detection with MRI is not always trouble-free, though. Calcified metastases will be difficult to spot, and there can also be problems with artifacts.

Different sequences may be put together to make a comprehensive lung MRI protocol, he said. This protocol should be able to address a number of clinical questions, including pneumonia, solid lesions, pulmonary embolism, chronic airway disease, and tumor staging (mediastinal and chest wall invasion).

He showed a selection of 10 T1- and T2-weighted sequences that could be combined in various ways to make such a protocol. The ideal in-room time for such a protocol is 15 minutes.

Speaking in the same session, Dr. Sebastian Ley, a radiologist at the University Hospital in Heidelberg, explained how steady-state free precession and contrast-enhanced MRA sequences can both be used to visualize the pulmonary arteries. The SSFP technique has the advantage of being freebreathing, whereas MRA is a breath-hold imaging technique, requiring patient cooperation. The two can be combined to make a seven-minute protocol for pulmonary embolism screening.

Ley said either MRI or CT could be used when assessing patients with chronic pulmonary vascular disease. In the case of congenital abnormalities, MRA and MR perfusion imaging are the best choice, he said.

The lungs have quite literally been a black hole for MRI for many years.

Advantages push lung MR imaging closer to use in clinical practice

The lungs have quite literally been a black hole for MRI for many years. Now advances in hardware and imaging techniques are helping lung MRI move into the clinical arena. 

 There are several reasons to use MRI for lung studies, Prof. Hans-Ulrich Kauczor, director of diagnostic radiology at the University Hospital in Heidelberg, Germany, told delegates at Sunday's New Horizons session. The modality can provide a comprehensive structural and functional assessment of the lungs in a single examination and has the potential to yield quantitative measurements. MRI's chief advantage, however, over CT is the absence of ionizing radiation. 



 "No radiation is better than a lot of radiation, and no radiation is also better than low radiation," said Kauczor, who chaired the session. 

 Although lung MRI started about 25 years ago, with the first studies being conducted in the 1980s, researchers were unable to show any clinical value. The techniques were revived in the 1990s by select groups who explored the idea of hyperpolarized gas imaging, but once again the modality failed to make the transition into clinical practice. Over the past 10 years, however, the development of MR-specific contrast agents and the launch of next-generation systems offering parallel imaging have improved the quality of lung MRI. 

 Will the removal of technological barriers lead to broad clinical acceptance and applications in the forthcoming years? Kauczor followed this question with a provocative vision: MRI can simplify the current diagnostic workup for patients presenting with suspected pulmonary disease. 

 "Pulmonary lung function test, lab test, chest x-ray, echo, CT, bronchoscopy, scintigraphy... Why not try to solve all the stuff that is addressed nowadays by four or five imaging techniques with a single imaging technique, namely MRI?" he said. 

 The wide variety of lung MRI techniques was set out by Dr. Jim Wild, a medical physicist at the University of Sheffield in the U.K. His checklist included standard proton MRI, oxygen-enhanced imaging, contrast-enhanced pulmonary angiography, perfusion imaging, and hyperpolarized gas MRI (helium and xenon). 

 Wild acknowledged that some of the methods he presented would only ever be of value to radiology researchers. Others could make the transition into clinical practice, so long as the methods were simplified. 

 "Overall, the future looks bright for lung MRI," he said. 

 There is definitely light at the end of the tunnel for lung MRI, according to Dr. Jürgen Biederer, a radiologist at the University Hospital in Kiel, Germany. Biederer drew on examples from published literature to show the clinical merits of breath-hold and free-breathing sequences when seeking out neoplasms or evaluating inflammatory lung disease. 

 In the case of small nodular lesions, for example, MRI was shown to rival CT in terms of sensitivity. CT can detect 65% to 85% of nodules sized between 5 and 10 mm in diameter. Depending on the sequence, MRI has a sensitivity of ~75% to ~90% for 3 to 5-mm nodules, rising to ~95% to ~100% for 6 to 10-mm nodules. 

 "It is easier to read lung nodules on MRI than CT because they really stand out on a black background," Biederer said. 

 Lesion detection with MRI is not always trouble-free, though. Calcified metastases will be difficult to spot, and there can also be problems with artifacts. 

 Different sequences may be put together to make a comprehensive lung MRI protocol, he said. This protocol should be able to address a number of clinical questions, including pneumonia, solid lesions, pulmonary embolism, chronic airway disease, and tumor staging (mediastinal and chest wall invasion). 

 He showed a selection of 10 T1- and T2-weighted sequences that could be combined in various ways to make such a protocol. The ideal in-room time for such a protocol is 15 minutes. Some of the suggested combinations fit into this time window, others need an extra five or 10 minutes. 

 Speaking in the same session, Dr. Sebastian Ley, a radiologist at the University Hospital in Heidelberg, explained how steady-state free precession and contrast-enhanced MRA sequences can both be used to visualize the pulmonary arteries. The SSFP technique has the advantage of being free-breathing, whereas MRA is a breath-hold imaging technique, requiring patient cooperation. The two can be combined to make a seven-minute protocol for pulmonary embolism screening. 

 Ley predicted that CT angiography would typically be preferred in the acute setting, owing to the logistics of MRI. Either MRI or CT could be used when assessing patients with chronic pulmonary vascular disease. In the case of congenital abnormalities, MRA and MR perfusion imaging are the best choice, he said. 



Note: a version of this article appeared in the 2010 

Paula Gould

Articles

Europe lacks consistent emergency radiology subspecialty training

Repeatability questions complicate search for imaging biomarkers

Advantages push lung MR imaging closer to use in clinical practice

Lung MR imaging prepares for a bright clinical future