Clinical Indications for Fluoroscopy
In orthopedic procedures, the surgeon might use fluoroscopy to visualize the broken bones during the reduction procedure in live-field. This is rarely done nowadays. Fluoroscopy is also used in cardiovascular interventions to monitor the introduction of the catheter. This discussion will focus on the application of fluoroscopy in gastrointestinal disease.
Use of Barium
Esophageal functional and motility disorders can be visualized and assessed with fluoroscopy. Barium is used to make the stomach, esophagus, or oropharynx opaque to X-rays. Because of the toxicity of barium when extravagated from a perforated viscus, its use in clinical practice is becoming less common.
Fluoroscopy is a solely diagnostic procedure which makes it inferior to endoscopy which can be also therapeutic. Additionally, fluoroscopy uses ionizing radiation which makes it contraindicated in pregnant women.
Fluoroscopy and Its Safety
Fluoroscopy uses conventional X-rays to obtain live still pictures or a video of the body of the patient. The radiation dose of this procedure in the past days was very high. Nowadays, many advances have been introduced to the fluoroscopy equipment to minimize the amount of radiation and lower the associated risks.
Now, all fluoroscopy machines have a display that shows the duration and cumulative radiation exposure to the patient. This can guide the making process of the doctor’s decision and can make the doctor terminate the procedure if the duration is considered to be too long.
Fluoroscopy machines now use better X-ray filters to minimize radiation injury with long procedures. Additionally, the irradiated fields now are much smaller compared to the old fluoroscopy devices. Images can now be digitally stored which means the doctor can go back to previous images without re-exposing the patient to radiation again. Finally, accurate laser localization is now used to precisely identify your target so that unnecessary repetitions are not needed.
Gastroesophageal Reflux Imaging
Upper gastrointestinal series study
Patients presenting with heartburn or other symptoms suggestive of gastroesophageal reflux disease should receive an upper gastrointestinal series study with contrast enhancement. This procedure is the first imaging study to be performed in any patient suspected to have gastroesophageal reflux disease.
The main goal of the upper gastrointestinal series is to identify the anatomy of the esophagus and exclude strictures. Barium esophagograms or barium swallows are the main methods used to identify structural abnormalities of the esophagus, esophageal hiatus, strictures, ulcers or hiatal hernias.
Typically, the barium esophagogram is performed on multiple phases. The patient is instructed to swallow a high-density barium solution and double-contrast views are taken with the patient in the upright and prone positions. Lower-density barium suspension is also used in the subsequent step. Finally, mucosal relief images are obtained.
Esophagitis is better visualized with double-contrast imaging. Esophageal strictures, rings or hiatal hernias are better visualized with single-contrast techniques.
While these images can be obtained with routine radiographs, their usability can be improved with fluoroscopy. Fluoroscopy makes it easier to appreciate the reflux part of the disease. Additionally, fluoroscopy can produce live videos of the barium swallow study.
Unfortunately, the degree of confidence in the results of these studies is low; therefore, these studies are usually used to detect severe esophageal lesions that are known to complicate the endoscopy procedure afterwards, but are not specific enough to confirm the diagnosis of esophageal reflux disease.
Achalasia is an esophageal motor disorder that is characterized by an increased tone in the lower esophageal sphincter. Peristalsis movements are absent in the distal portion of the esophagus and the lower esophageal sphincter tends to show poor co-ordination with swallowing in the patient. Patients with achalasia present with dysphagia to solids and liquids, chest pain and regurgitation that are unresponsive to proton pump inhibitors.
Esophageal motility testing
Esophageal motility testing is indicated in any patient suspected to have achalasia. Esophageal motility testing consists of manometry testing of the pressure of the lower esophageal sphincter and testing for the presence of peristalsis. Patients with a residual lower esophageal sphincter pressure of 10 mmHg or more and absent peristalsis in the distal part of the esophagus are diagnosed with achalasia.
Use of barium in atypical presentation
Unfortunately, this typical picture is not seen in all patients with achalasia. Patients with less than optimum picture benefit from barium swallow and esophagogram studies especially when combined with fluoroscopy. The goal of the barium study is to provide supporting evidence for the diagnosis of achalasia.
The main findings of barium swallow studies in achalasia include the bird’s beak deformity and esophageal dilation. The correlation between the degree of esophageal dilation and the severity of the symptoms is not always straightforward.
Patients with a normal barium swallow study who have symptoms and signs of achalasia should still undergo esophageal manometry testing and possibly endoscopy.
Patients with symptoms and signs suggestive of esophageal obstruction should also undergo a computed tomography scan to exclude esophageal carcinoma, strictures, or other malignant diseases. Oral contrast with computed tomography scanning of the upper gastrointestinal tract can provide excellent images for 3D reconstruction of the upper gastrointestinal tract.
Small Bowel Follow-Through
This technique is no longer used in the clinical practice, but it is still good to explain the procedure. A small bowel follow-through uses a contrast to visualize the stomach and upper part of the small intestine to exclude duodenal disease for instance. The diagnostic yield of small bowel follow-through ranges between 0 and 20%. Nowadays, computed tomography enterography, and capsule endoscopy have replaced small bowel follow-through for the imaging evaluation of small bowel disease.
Barium Enema and Colon Cancer
Barium enema is no longer commonly used in the evaluation of the colon cancer patient. Regardless, it is nice to mention some common findings on barium enema in patients with colon cancer for educational purposes.
The carcinoma can appear as an apple core lesion after the administration of the barium enema. This is due to stricture formation and ulceration. Polyps and adenomatous polyposis can be also easily visualized with a barium enema study. The accuracy of a double-contrast barium enema in the diagnosis of colon cancer is quite good, as high as 80%. The main draw-back of barium enema as an imaging diagnostic modality for colon cancer is the very high false-negative rate (22%). The availability of colonoscopy, computed tomography and magnetic resonance imaging studies made the radiologist’s reliance on barium enema very little.