Interventional Radiology

A sub-specialty of radiology, Interventional radiology - IR has contributed significantly to medical developments in recent years. Patients are diagnosed and treated using minimally invasive imaging techniques such as X-ray, MRI and ultrasound for guidance. In addition to diagnosis, new treatment options are offered by techniques in Interventional radiology (also known as Surgical Radiology)- patients are treated with lesser risk and shorter hospital stays.

The advantage of IR procedures is that they can be used in almost every organ system - be it abdomen, central nervous system, chest, heart and vascular, musculoskeletal, genito-urinary and other organs and soft tissues.

Interventional Radiologists

Patient evaluation and management are provided by Interventional radiologists, who are doctors trained in radiology and in minimally invasive procedures, skilled in interpreting X rays, ultrasounds and CT and other imaging techniques. While surgery was the only available option for a number of conditions a few years back, these days the expertise of Interventional radiologists with imaging technique enables them to guide small catheters, that are only a few millimeters in diameter and guide wires through blood vessels or other organ pathways to treat many conditions. Diseases and conditions are diagnosed and treated percutaneously with minimally invasive procedures.

Benefits and uses of Interventional radiology

This is an imaging technique using cutting-edge equipment for accurate diagnosis and treatment, a minimally invasive procedure through a small nick in the skin, minimizing the patient's discomfort and recovery time. These days, there is hardly any area in hospital medicine where IR has not impacted patient management.

These procedures require only local anesthesia, and short stays at the hospital. Sick patients who are unfit to undergo surgery can also undergo these techniques. Recovery post IR procedure is less painful than when the patient undergoes surgical procedures.

These image guided medical procedures use CT, MRI, fluoroscopy and ultrasound to view targeted areas. This makes the vessels clearly visible under imaging. A thin catheter is used to deliver the contrast material into a particular blood vessel and shows the inside of the vessel allowing the radiologist to locate blockages. Some examples of interventional radiology procedures include:

• Angiography or Angioplasty
  
• Stent placement
  
• Control bleeding with Embolization
  
• Tumor embolization
  
• Vertebroplasty and Kyphoplasty
  
• Needle biopsies for different organs including lungs and thyroid gland
  
• Tumor ablation
  
• Breast biopsy by stereotactic or ultrasound techniques
  
• Uterine artery embolization
  
• Feeding tube placement
  
• Venous access catheter placement

Using Interventional radiology

By minimizing the physical trauma to the patient, non-surgical interventions also reduce infection rates and recovery time and shorten hospital stays.

• Blood vessel disease such as narrowing of arteries leading to restricted flow of blood
  
• Expanded arteries at risk of rupture and bleeding
  
• Bleeding or hemorrhage which is the most common vascular emergency treated by IR.
  
• Blood clots in the lung
  
• Dilated veins or varicose veins that most commonly occur in the legs but can occur in the pelvis and scrotum and can be treated by blocking the vein by heat treatment or using embolization techniques.
  
• Tumor therapies in liver intended to shrink or destroy them in their primary site.
  
• Kidney and other tumors by destructive therapies
  
• Uterine fibroids which cause heavy menstrual bleeding and pain caused by benign tumors called fibroids
  
• Kidney stones that can cause pain
  
• Infection and blockage in the kidney and gall stones, one of the most common upper abdominal disorders.

Pulmonary Infarction

Infarction means 'tissue death' in medical terminology. It is caused by obstruction of blood supply to the tissue leading to lack of oxygen. Infarct, which refers to the resulting lesion is derived from Latin, 'infarctus' which means 'stuffed into'. Pulmonary infarction refers to the death of a small area of lung resulting from pulmonary embolism. It occurs in a small, dead end pulmonary artery.

How does pulmonary infarction occur ?

Pulmonary infarction results from free floating thrombus, when many material substances including fat, tumor, septic emboli, air, and amniotic fluid and injected foreign material may form an emboli and move to the pulmonary circulation. In other words, plugging of a branch of the pulmonary artery by a clot (thrombosis) or by a piece of clot carried by the blood stream to the lung from a thrombus located elsewhere can result in pulmonary infarction. The involved area of the lung ceases to function and complication of the thrombosed veins leads to heart disease.

Causes of pulmonary infarction

The most common cause of pulmonary infarction is pulmonary embolism, but there are other conditions which can cause pulmonary infarction including cancer, and autoimmune diseases such as lupus. Sometimes, this condition may occur following a surgery. Other underlying conditions especially in children with pulmonary emboli include sickle cell disease, nephrotic syndrome, chemotherapy and Inherited hyper coagulable state and Vasculitis.

Symptoms of pulmonary infarction

Symptoms associated with pulmonary infarction include shortness of breath, chest pain, and blood sputum or hemoptysis. Sudden piercing pain in the chest which often radiates to the shoulder is noticed. Difficulty in breathing, irritating cough and blood tinged sputum are other signs. Persistent hiccups are present. Most often the patient is anxious with a rapid pulse, sweats profusely and has an elevated body temperature. In some severe cases, the patient may be in a state of shock.

Diagnosis of pulmonary infarction

Reflex broncho constriction is often associated with pulmonary embolism. Increased breathing and decreased pulmonary compliance with diminished surfactant levels may occur due to pulmonary infarction. This contributes to increased work of breathing and diminished oxygen levels. In sickle cell disease, there is sickling of RBCs within the small blood vessels of the lungs due to dehydration as a result of fever, Tachypnea (rapid breathing) and decreased intake, which can precipitate in a cycle of relative de oxygenation that further exacerbates the sickling tendency. Many also suffer a component of reactive airway disease and oxygenation is further decreased due to this factor.

Morbidity may include pulmonary hypertension, right ventricular failure and Cor Pulmonale, paradoxical embolization in patients with intracardiac defects, and sometimes side effects of medications used to treat pulmonary embolism. If pulmonary embolism is large, there could develop right ventricular strain and right heart failure as there is sudden increase in pulmonary artery pressure leading to right heart failure. A sudden pressure in the right ventricle can cause a leftward shift of the intraventricular septum, which may result in a classic obstructive shock, thereby impairing left ventricular filling.

Treating pulmonary infarction

It is timely treatment that is vital. If symptoms of pulmonary infection develop while at home, consult a physician at once. In case, shock develops, it is essential to get first aid treatment. Many times, patients are already in the hospital when pulmonary infarction occurs. Administration of oxygen, use of anticoagulants and prevention of infection are some other suggested line of treatment. Surgery may also be indicated.

CBCT Scan

CBCT, also known as C-arm CT, Cone Beam Volume CT or flat panel CY is a medical imaging technique, like a conventional CT scan. It provides fast and accurate visualization of bony anatomical structures in three dimensions. It is essentially X-ray computed Tomography where the X rays are divergent, forming a cone. Unlike traditional dental x-rays that are flat images, CBCT scan can provide multiple images of the teeth, soft tissues, bone and nerve pathways. The image quality is better due to reduced scatter radiation. These images help compile exact 3D images of various angles of the face and jaw. It also allows the dentist to zoom into specific maxillofacial structures with alternate angles for clearer evaluation.

CBCT applications

CBCT is important in planning and diagnosis in implant dentistry and interventional radiology among other things. In dentistry, it is used in oral surgery, endodontics and orthodontics.

CBCT is an important tool in image-guided radiation therapy for patient positioning and verification. Nearly 600 distinct images can be captured by rotating the CBCT scanner around the patient's head. In interventional radiology, a single 200 degree rotation over the region of interest provides volumetric data. The scanning software collects the data and reconstructs it, producing a digital volume composed of three dimensional voxels of anatomical data that can be manipulated and visualized with specialized software.

CBCT offers invaluable information in planning and assessment of surgical implants. A dental cone beam scan is the preferred method for pre surgical assessment of dental implant sites. Since CBCT is a 3D rendition, there are several structures that can be viewed with this facility, which are not available with conventional 2D radiology. CBCT offers an undistorted view of the dentition. That is why it is used for accurately visualizing both erupted and non erupted teeth. It is also used in tooth root orientation and anomalous structures.

Use of CBCT in Interventional Radiology (IR)

The scanner is mounted on a C arm in the IR suite offering real time imaging. Since this can be done on a stationary patient, it eliminates the time spent to transfer a patient from the Angiography suite to a conventional computed Tomography scanner. It also facilitates many applications of CBCT during IR procedures. Both primary and supplementary form of imaging can be done with CBCT. For fluoroscopy and soft tissues, it can be very helpful during complex procedures to reduce patient's radiation exposure.

Clinical applications of CBCT

In hepatocellular carcinoma, CBCT contrast confirms that the proper artery is selected to deliver the therapy. For benign prostatic hypertrophy BPH, CBCT provides soft tissue details needed to visualize prostatic enhancement, identify duplicated prostatic arteries and avoid non target embolization. During abscess drainage, CBCT confirms needle tip location after placement under ultrasound and confirms drain placement by revealing contrast injection into the desired location.

For adenoma adrenal vein sampling, contrast enhanced CBCT shows perfusion of the adrenal gland to confirm catheter placement for obtaining a satisfactory sample. During stent placement, CBCT improves the visualization of intracranial and extracranial stents. CBCT guides needle placement and allows diagnostic accuracy, sensitivity and specificity in lung nodules. After correction of vascular anomalies, CBCT sensitively detects small infarcts in tissue during the procedure to prevent further shunting.

Risks

Although it is a compact, faster and safer version of the regular CT, dental CBCT delivers more radiation than conventional dental X rays. Even properly shielded CBCT exposes patients to radiation many times more than 2D digital dental x rays. However, improved outcomes at lowered cost and time saving, reduced morbidity and reduced need for exploratory procedures and other such benefits of CBCT continue to make it popular with practitioners.