Introduction:
Pancreas is a gland involved not only in digestion, but also endocrine function, it can get affected by pancreatic cancer. Imaging techniques are necessary for the diagnosis of pancreatic cancer. The imaging modalities commonly used to identify pancreatic cancer include ultrasound, CT (computed tomography) scan, MRI, and endoscopic techniques such as EUS and endoscopic retrograde cholangiopancreatography (ERCP).
What Is Pancreatic Cancer?
Pancreatic cancer refers to developing malignant tumors within the pancreas, a gland positioned between the spine and the stomach in the abdominal region. It makes hormones that maintain the blood-sugar level and enzymes that help digestion. Pancreatic cancer is a malignant digestive system tumor due to a change in the pancreatic cells, which mutate (change) and multiply rapidly to grow into a tumor. Pancreatic cancer remains asymptomatic initially, but later some of the symptoms are seen, such as jaundice, dark-colored urine, itchy skin, nausea, vomiting, blood clot, and weight loss.
Early-stage pancreatic tumors do not show up on imaging tests usually. Due to this, many patients do not receive a diagnosis until the cancer spreads (metastasizes). Pancreatic cancer is also resistant to many cancer-treating drugs making it more challenging to treat. Many new diagnoses and treatment modalities are being made for pancreatic cancer.
How Is Pancreatic Cancer Caused?
There is n definitive cause of pancreatic cancer, but a few risk factors are associated with it. These factors include:
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Smoking: smoking cigarettes, cigars, and tobacco can cause pancreatic cancer.
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Obesity: especially if there is extra weight around the waist.
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Diabetes: Sudden-onset diabetes could be a sign of pancreatic cancer, particularly type 2.
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Chemicals: Exposure to a few substances, like pesticides and petrochemicals.
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Chronic Pancreatitis: It is a permanent inflammation of the pancreas.
- Hereditary Chronic Pancreatitis: It is caused due to gene changes (mutations) passed from biological parent to child.
What Are the Diagnostic Methods for Pancreatic Cancer?
Most pancreatic cancer patients are diagnosed at an advanced stage or metastasis. Thus, an early diagnosis of pancreatic cancer is important for improving its prognosis. Some of the traditional diagnostic procedures include:
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Transabdominal Ultrasound: It is the first screening modality. It can identify any abnormality present in the pancreas.
- CT (Computed Tomography)- It is a scanning method to detect various diseases. A combination of X-rays and advanced computer technology generates a three-dimensional image of the soft tissues and bones.
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MRI (Magnetic Resonance Imaging)- It creates precise images of the structures inside the body with the help of a large magnet, radio waves, and a computer.
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PET (Positron Emission Tomography)- It detects early signs of cancer, heart disease, and brain conditions. It uses an injection of a radioactive tracer that helps detect the diseased cells.
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Endoscopic Ultrasound- An endoscopic ultrasound (EUS) procedure examines the inner part of the digestive tract. It can detect pancreatic, colon, and cancer that spreads to other parts of the body.
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EUS-FNA: It is an advanced method used to view the pancreas from the duodenum or the stomach to depict high-resolution images of the pancreas. It is believed to be one of the most effective methods for diagnosing focal pancreatic lesions, especially in people with tumors of size less than 1.1 inch or less. EUS also has the unique potential to obtain specimens for histopathological diagnosis using EUS-guided FNA.
These traditional methods fail to diagnose pancreatic cancer at an early stage. Thus, new treatment modalities are made for the diagnosis of cancer.
What Are the Advanced Modalities for Diagnosing Pancreatic Cancer?
The advanced methods for the imaging of pancreatic cancer include:
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Dual-Energy CT and Low Tube Voltage Techniques: MDCT (Multidetector computed tomography) is highly recommended for its use in pancreatic cancer for the diagnosis and, staging, finding of small pancreatic cancers (< 0.7 inch in diameter). Dual-energy CT and low-voltage techniques are very efficient in detecting small pancreatic cancers. Low voltage CT can increase the amount of X-rays absorption of the iodine by expanding the gap between the mean adequate energy of the X-ray spectrum and the K-edge of iodine. As a result, the increased contrast enhancement of the normal pancreatic parenchyma maximizes contrast to typically poorly vascularized cancers.
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Iterative Reconstruction Algorithm on MDCT: The Iterative reconstruction algorithm on MDCT assures the preservation and enhancement of the diagnostic reliability of the CT with fewer radiation doses. This is achieved by lowering the image noise during the reconstruction procedure. Lowering the image noise can be used for high spatial resolution pancreatic CT imaging, generally characterized by high quality 1–2 mm, thin slice CT images.
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Dynamic Contrast-Enhanced MRI (DCE-MRI) And Diffusion-Weighted Imaging (DWI): DCE-MRI is a diagnostic procedure that is seen to give enhancement patterns and perfusion parameters which are objective and helps in the observation of malignant diseases by diagnosing and treating them. This method differentiates between pancreatic cancer and pancreatic neuroendocrine tumor. While DWI characterizes pancreatic lesions of different pathological types, including cystic lesions, pancreatitis, and malignant tumors. Benefits of DWI include its soft tissue contrast for focal lesion finding, and it may allow prior detection of pancreatic adenocarcinoma since these neoplasms have increased signal intensity.
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PET/CT: Positron emission tomography scan when done along with CT scan is called as PET/CT scan. This scan is used for the detection of cancer.
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Hybrid PET/MRI: Integrated PET and MRI scanners have to now be available for humans. This integrated technique is known for its superior soft-tissue contrast resolution, multiplanar imaging acquisition, and functional imaging. PET-MRIs are used for staging in patients with locally advanced pancreatic tumors and tumor response in people with neo-adjuvant chemoradiation. This method is still in the developmental stage, and further studies are ongoing for its effectiveness and uniqueness in the screening of pancreatic cancer compared to the other available techniques.
A few blood tests also may be used as corroborative evidence for pancreatic cancer such as CA19-9 levels
Conclusion:
Pancreatic cancer is one of the leading cancer in the world. It is a cancer of the pancreas, a gland of the digestive tract. It makes hormones that help maintain the blood sugar level and produces enzymes that aid digestion. The diagnosis of a pancreatic tumor is delayed as its symptoms also appear later. In some cases, diagnosis is done even after the cancer metastasizes. The traditional diagnostic methods were CT scans, MRI, ultrasound, etc.
Therefore, developing new screening techniques for early detection of pancreatic cancer is essential. The new advanced modalities for diagnosis include Hybrid PET-MRI, dual-energy CT- and low-voltage techniques, iterative reconstruction algorithm on MDCT, etc. These have early detection possible, and several other studies are also going on for further advancement.
