Maximum Accuracy for the Youngest Cancer PatientsA Device Combining Magnetic Resonance Imaging and Positron Emission Tomography Can Give New Hope to Children with Cancer

The University of Leipzig on the advantages of owning an MR-PET

April 16, 2014 | Finally, there is a device available for children with cancer that offers the best of two worlds in imaging: Combining magnetic resonance imaging and positron emission tomography enables high-precision visualization of the morphology and function of malignant tumors in children, with minimal radiation exposure.

 

Text: Martina Lenzen-Schulte, MD
Photos: Christoph Busse

 

  • Biograph mMR is the only system that enables simultaneous whole-body MR and PET scanning. The MRI system, which is based on a 3 Tesla unit, has proven to be ideal for use with children.
  • Biograph mMR represents an excellent device for pediatric oncology that combines all of the requirements for morphological resolution and detection of metabolic activity with limited radiation.
  • The question of how a patient will respond to a treatment can be answered reliably and more precisely than with single modalities, for pediatric tumors. The Leipzig studies recommend that the Biograph mMR system be integrated into follow-up care protocols.
  • The extremely important step of localizing elevated metabolic activity at the tumor site is crucial to achieving the correct biopsy, and hybrid imaging delivers better results in this process.

Performing both exams simultaneously means that there is no need to undergo repeated anesthetics. It also reduces the strain on children (and parents) and improves workflow. At 40 to 50 minutes, the scanning time is significantly lower than initially assumed.

Professor Hirsch on advantages of molecular MRI for Pediatric Oncology
Professor Franz Wolfgang Hirsch, MD, with Professor Henryk Barthel, MD.

“The Biograph mMR is practically made for children1,” is the verdict from Professor Franz Wolfgang Hirsch, MD, Head of the independent Pediatric Radiology Department at the University Medical Center in Leipzig, Germany, on the advantages that the hybrid system offers for his young patients. “We have known for a long time that MRI shows us anatomical structures with excellent image quality,” Hirsch says. “But what we find especially impressive is that this is possible with a 3 Tesla unit on these small bodies, even without disruptive artifacts. That wasn’t always possible with the larger diameter of an adult body,” Hirsch says. To this positive point, he adds, “I’m fairly surprised by the excellent image quality.”

 

Enabling Measurements of Tumor Responses
Professor Henryk Barthel, MD, Assistant Medical Director at Leipzig University Medical Center’s Department of Nuclear Medicine Clinic and Polyclinic, agrees: “That’s definitely also true of the PET component. We see that the detection sensitivity is higher than with conventional measurements. The system truly offers the best of both worlds.”

This makes diagnosis more accurate than before with MR alone, as the PET component makes metabolic activity in the tumor cells not only visible, but also quantifiable. “In my opinion, it has been very clearly shown that this is the most reliable criterion for responding to tumor therapy. That means we can also quantify the response to the treatment,” Barthel says.

 

The information obtained with molecular MRI helps with follow-up care
Examination room in Pediatric Radiology

Advantages Beyond Diagnosis in Pediatric Oncology
This is important in terms of the further care provided to the young cancer patients: “We also play a major role in providing follow-up care for these patients, for example, those with common pediatric forms of cancer, such as lymphoma – cancer of the lymph nodes – or various types of blood cancer or leukemia,” Hirsch explains.

“So in a patient with lymphoma, if we need whole-body staging, we can now use the Biograph mMR to achieve it, to a level of accuracy we have never known before, with extremely low radiation exposure,” the pediatric radiologist points out. “Even more than for initial classification of the tumor, this plays a major role in the further course of treatment. A malignant lymph node tumor shrinks during treatment, but some residual tissue or stroma remains,” Hirsch explains.

 

Unprecedented Quality in Follow-Up Care
In the case of follow-up care especially, hybrid MR and PET can provide valuable information: “In evaluating the tumor residue, the MRI alone left us with a number of unanswered questions. Merely based on the anatomy of the structures, it is not possible to say with certainty how biologically active the remaining tissue still is,” Hirsch says. This information is now supplied. And that, Barthel concludes, “is a truly great stride in the quality of follow-up care.”

If one were to consider only the information from the MRI, the remnants of a tumor might in some cases seem more dangerous than they actually are. “But we nuclear medicine specialists can then see via PET that the tumor is no longer vital. That means it definitely responded well to treatment, and we can confirm that the cancer is in full remission,” Barthel says.  

 

The University of Leipzig considerably enhanced diagnostic accuracy
The University of Leipzig is one of the few medical centers in Germany to own an MR-PET.

Adding by Subtracting
This spares the patient further or more aggressive rounds of treatment. “That is precisely the goal in pediatric oncology,” Hirsch points out. Physicians treating these forms of cancer in children are now moving forward cautiously, with one motto: “As little as possible, as much as necessary.” In the process, Hirsch says, “the new options in hybrid imaging are an invaluable help.”

Hirsch assumes that in the long run, this will result in new standards in follow-up care: “I think that in the future, this kind of monitoring of the course of the disease should replace the X-ray scans that are still required in study protocols today.” 


Improved Workflow, Reduced Strain
Ultimately, the parents only have to take their sick child to the hospital for one scan. Besides, as Hirsch explains, that also means “that we only have to anesthetize those patients who need it for the examination once.”

This is because the accuracy of imaging depends on various factors, not least among them how well it can be correlated with breathing movements. “To do this, the device uses a breathing sensor attached to a belt to trigger the image to start at the end of inhalation,” Barthel says, describing the process. “But not all children can breathe as calmly as necessary to achieve the most accurate measurement possible, and that means anesthesia is necessary,” he adds.

On the whole, it had been estimated that scanning would take about one and a half hours, but due to the high quality of the images, the time needed is now much shorter: “We can manage with 40 to 50 minutes per exam. The unexpectedly good quality of the images makes that possible for us,” Hirsch says. Thus, thanks to more accurate diagnostics, not only is the strain on children and their parents noticeably reduced, but the clinical workflow is also improved at the same time.

 

Professor Wolfgang Hirsch, MD, gives hope to children with cancer
Professor Wolfgang Hirsch, MD

Professor Franz Wolfgang Hirsch, MD, studied medicine at the University of Halle and went on to work at locations including the University Medical Center in Halle and Royal Marsden Hospital, in London. In 2002, he was appointed Professor of Pediatric Radiology at the University of Leipzig, where he heads the Pediatric Radiology unit within the Department of Imaging and Radiation Medicine. Hirsch chaired the Deutsche Röntgengesellschaft (German Radiology Society, DRG) pediatric radiology task force and served as a member of the board of the Gesellschaft für Pädiatrische Radiologie (Pediatric Radiology Society). He is a member of the board of directors for the DRG’s Academy for Continuing and Professional Radiology Education. His main scientific interest is the use of simultaneous MR and PET in pediatric diagnostics and fetal MRI.    

Professor Barthel, MD, Assistant Medical Director at Leipzig University
Professor Henryk Barthel, MD

Professor Henryk Barthel, MD, studied medicine at the universities of Greifswald and Leipzig from 1988 to 1994. After stints practicing medicine and as a researcher in Heidelberg, Leipzig, and London, he has been Assistant Medical Director at the Department of Nuclear Medicine, headed by Professor Osama Sabri, MD, at the University Medical Center in Leipzig since 2003. His job encompasses neuro-PET and simultaneous PET/MR imaging. His scientific work focuses particularly on PET and simultaneous PET/MR imaging in dementia and stroke patients and in visualizing stem cells. He is a member of the neuronuclear medicine task force of the German Nuclear Medicine Society (Deutsche Gesellschaft für Nuklearmedizin) and Vice President Elect of the Brain Imaging Council of the U.S.-based Society of Nuclear Medicine and Molecular Imaging.


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