|Year : 2018 | Volume
| Issue : 4 | Page : 417-418
Potential role of whole-body diffusion magnetic resonance imaging in tumor staging for pregnant patients with cancer
Abhishek Mahajan, GV Santhosh Kumar, Tanvi Vaidya, Meenakshi Thakur, Subhash Desai
Department of Radiodiagnosis and Imaging, Tata Memorial Hospital, Mumbai, Maharashtra, India
|Date of Web Publication||28-Feb-2019|
Department of Radiodiagnosis and Imaging, Tata Memorial Hospital, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
Malignancy during pregnancy poses a serious threat to the growing fetus. In this special situation, the diagnostic procedures and treatment to cancer will be more damaging to the developing fetus than the cancer itself. However, to safeguard the health of the mother from cancer, appropriate diagnostic and therapeutic tools are to be used that would minimize risk to fetal health. Diffusion-weighted whole-body imaging with background body signal suppression has the potential to answer most of these diagnostic dilemmas in the case of malignancy in pregnancy. This is one of the first such reports highlighting the role of a noninvasive, nonionizing whole-body imaging technique which does not require external contrast injection and can also be used for monitoring treatment response.
Keywords: Diffusion-weighted imaging, diffusion-weighted whole-body imaging with background body signal suppression, imaging, obstetrics, oncology, pregnancy
|How to cite this article:|
Mahajan A, Santhosh Kumar G V, Vaidya T, Thakur M, Desai S. Potential role of whole-body diffusion magnetic resonance imaging in tumor staging for pregnant patients with cancer. Indian J Cancer 2018;55:417-8
|How to cite this URL:|
Mahajan A, Santhosh Kumar G V, Vaidya T, Thakur M, Desai S. Potential role of whole-body diffusion magnetic resonance imaging in tumor staging for pregnant patients with cancer. Indian J Cancer [serial online] 2018 [cited 2019 Nov 13];55:417-8. Available from: http://www.indianjcancer.com/text.asp?2018/55/4/417/253286
| » Introduction|| |
Pregnancy heralds the genesis of life, the procreation of mankind, and the singular precious event in any women's life. Nothing can be more devastating than the occurrence of any serious medical ailment that could affect the pregnant woman, her fetus, or both. The use of medical technology for diagnosing and treating maladies that befall either of them may pose threat to healthier one. Thus, it is prudent to use a technology that would be associated with minimal risk, especially for the growing fetus. The treating physician needs to use his acumen in requesting imaging modalities that will help diagnose, stage, and prognosticate disease, and at the same time having negligible associated risks. Here, sonographic and magnetic imaging win hands down over the use of ionizing radiations.
Pregnancy and imaging
In the unfortunate event of the pregnant woman harboring malignancy, it is a challenge to choose the imaging modality for staging. Radiological staging of malignancy depends mainly on ionizing radiation of computed tomography (CT) and nuclear imaging modalities, as well as the use of intravenous application of contrast agents. Considering the harmful effects of the ionizing radiation to the developing fetus, these investigations are avoided as much as possible. Among the investigations not using ionizing radiation, magnetic resonance imaging (MRI) is preferred due to many inherent limitations of sonography. MRI, known for its use of nonionic waves for imaging in the internal structures of the body, is considered to be safer with no significant adverse effect on the mother and the growing fetus. No published human studies have proved about the harmful effects and risk of teratogenicity by MRI. Therefore, no special considerations are recommended for the first, versus any other, trimester in pregnancy.
Diffusion imaging – a potential imaging tool in pregnant patients with malignancy
The basic principle of diffusion-weighted imaging (DWI) is the molecular changes that occur in the tissue microenvironment and hindrance of the water molecule motion with respect to tissue cellularity. Due to the hypercellularity in the tumoral tissue, there is resultant restricted diffusivity of the water molecules, and hence the tumoral tissue shows restricted diffusion (lower apparent diffusion coefficient (ADC) values). DWI has become standard imaging sequence in brain imaging; breathing movements and susceptibility artifacts preclude its use in extracranial diffusion imaging. Hence, DWI was not popular for body imaging until recently; development of better coil technology and imaging sequences have overcome these problems.
One of the promising advancements of MRI is the diffusion-weighted whole-body imaging with background body signal suppression (DWIBS). The concept of DWIBS was first reported by Takahara et al. where they intentionally used free breathing scanning rather than breath-holding or respiratory triggering. DWIBS acquires diffusion-weighted data in volume and presents image as a three-dimensional maximum intensity projection. The background signal of the body is suppressed to reduce the noise and the resultant images look similar to the planar imaging of positron emission tomography scans.
Malignancy during pregnancy poses a serious threat to the growing fetus. In this special situation, appropriate diagnostic and therapeutic tools are to be used for disease management that would minimize risk to fetal health. DWIBS has the potential to answer all these diagnostic dilemmas in the case of malignancy in pregnancy [Figure 1]. The case depicted in [Figure 1] is that of a 30-year-old pregnant patient diagnosed with medullary carcinoma of the thyroid in her first trimester. She was found to have very high calcitonin levels (252 pg/mL), thus increasing the likelihood of distant metastases. A contrast-enhanced CT of the thorax, abdomen, and pelvis was indicated, but to avoid exposure to ionizing radiation and iodinated contrast, a whole-body MRI was performed. A whole-body MRI, including the DWIBS technique, is relatively safe for the mother and her fetus; it is accurate in mapping metastatic disease and in local staging of the tumor. Injectable contrast is also not required as most of the findings were evaluated from noncontrast scans. For this reason, it is becoming popular in oncoimaging of pregnant patients.
|Figure 1: A 3-month pregnant patient diagnosed with medullary carcinoma of the thyroid underwent whole-body magnetic resonance imaging for metastatic work-up. T2-W magnetic resonance images (a, b) showing primary thyroid disease in left lobe and a node at left level IV (white arrows). However, diffusion-weighted imaging (c) revealed multiple left central compartment and lateral compartment cervical nodes showing restricted diffusion (black arrows) with primary disease in the isthmus and pyramidal lobe of thyroid|
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A few things, however, need to be kept in mind. DWI highlights the sites of metastatic disease and the involved nodes. Several studies have showed usefulness of DWI and ADC measurement in differentiating benign and malignant lymph nodes as variable results.,, For this reason, a second confirmatory imaging using sonography and guided biopsy is required for tissue sampling. Furthermore, large patient cohort studies are needed for proving the efficacy of DWIBS making it a standard imaging in pregnancy with malignancy.
To summarize, DWIBS has the potential to become the imaging modality of choice for the staging of different malignant tumors that occur during pregnancy. The literature on this subject is currently lacking. This is one of the first such reports highlighting the role of a noninvasive, nonionizing whole-body imaging technique which does not require external contrast injection and can also be used for monitoring treatment response. Hoverer, large patient cohort studies are needed for proving the safety of DWIBS making it a standard imaging in pregnancy with malignancy.
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Conflicts of interest
There are no conflicts of interest.
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