Lymph check: SPECT-MRI detects cervical metastases

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  • Published: May 1, 2016
  • Author: David Bradley
  • Channels: MRI Spectroscopy
thumbnail image: Lymph check: SPECT-MRI detects cervical metastases

Lacking metastatic enlargement

Cervical cancer patients who do not have enlarged lymph nodes could benefit from imaging using SPECT-MRI imaging to determine whether their sentinel lymph nodes (SLNs) have become metastatic, according to a new study published in The Journal of Nuclear Medicine Credit: Blausen Medical Communications, Inc via Wikimedia donation

Cervical cancer patients who do not have enlarged lymph nodes could benefit from imaging using SPECT-MRI imaging to determine whether their sentinel lymph nodes (SLNs) have become metastatic, according to a new study published in The Journal of Nuclear Medicine.

There are more than half a million cases of cervical cancer reported each year, which makes it the fourth most common cancer in women worldwide. That is 186 women for every million in the USA, according to a University of Maryland study. Key to a positive outcome for those women is an early diagnosis followed by appropriate treatment, usually surgical removal of affected tissue or even radical hysterectomy, accompanied by chemo- or radio-therapy or a combination of both. A close examination of the sentinel lymph nodes is also carried out and is considered the most precise method of determining whether or not the cancer has spread to the lymph nodes. Unfortunately, if those lymph nodes are not enlarged, the oncology team can be lulled into a false sense of security and a false negative for metastases reported. A more definitive test based on SPECT-MRI could significantly reduce the number of false negatives in patients otherwise in the early stages of the disease and so save lives without recourse to invasive diagnostic procedures.

Now, a team from the University Medical Center Utrecht, in Netherlands, Jacob Hoogendam, Ronald Zweemer, Monique Hobbelink, Maurice van den Bosch, René Verheijen, and Wouter Veldhuis, has used the a metastable nuclear isomer [sic] of technetium-99, 99mTc, to create a nanocolloid for SPECT-MRI fusion that allows them to assess SLNs for size and in the absence of sharp demarcation.

Multidisciplinary potential

Hoogendam explains the potential: "An interesting aspect of this research, and the field in general, is that we are taking more and more steps toward combined technology to minimize invasive diagnostics in patients with cervical cancer," he says, adding that, "With these methods we aim to reduce morbidity via more tailored and informed selections between radical hysterectomy and chemo/radiation for each patient, instead of solely stage-based treatment selections."

The team evaluated stage IA1-IIB1 cervical cancer patients at their centre over a four-year period from March 2011 to February 2015. Patients who presented with enlarged lymph nodes in their conventional MRI were excluded from the study and given appropriate treatment. Those women who did not have enlarged SLN underwent a mapping procedure with preoperative 99mTc-nanocolloid SPECT-CT. The team could then fuse the datasets from SPECT and MRI, so that the SLNs could be identified on MRI precisely and correlated with histological results from each individual node.

The team gave the data to an experienced radiologist, who had no access to the histology, to retrospectively review all fused SPECT-MRIs and then to score morphologic SLN parameters on a standardized case report form. They then used logistic regression and receiver operating curves (ROC) to build a model of the parameters against the SLN status. Ultimately, they identified 136 SLNs that were eligible for analysis in 75 cases; 13 SLNs (almost 1 in 10 of those examined) contained metastases, eight patients. These metastases might otherwise have remained hidden until they gave rise to health problems in those patients.

Lymph awareness

"We need to be aware that a dichotomous lymph node cut-off on MRI, typically a 10 millimetre short axis diameter to determine whether it is suspicious or not, is relatively crude and certainly does not fit all patients," Hoogendam explains. "Our study investigated whether a more individualized, imaging-based assessment is possible for the small metastases that are currently missed on imaging [giving those worrying false negatives in MRI]." "The novelty of our study is the focused review of fewer than five sentinel nodes, instead of indiscriminately reviewing the entire pelvic lymphatic chain (up to 100 nodes per patient). Less is more." Hoogendam adds, "This new imaging approach is a first step, and we hope it sparks further research."

Hoogendam is now arguing for an interdisciplinary approach to both clinical practice and research because the sentinel node focus requires a combination of preoperative diagnostic imaging (SPECT), radiology (MRI), and the gynaecological oncology department for the intraoperative sentinel node procedure to be involved. "We should not be islands within a hospital; better interdisciplinary cooperation can synergistically lead to new insights, more relevant research questions, and better patient care," he suggests.

Related Links

J Nucl Med 2016, 57,551-556: "99mTc-nanocolloid SPECT-MRI fusion for the selective assessment of non-enlarged sentinel lymph nodes in patients with early stage cervical cancer"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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