Medical School · Year 4 · Radiology · includes a quiz and discussion video
Interventional Radiology and Special Topics
Year 4: Radiology Elective
Learning Objectives
By the end of this seminar, students will be able to:
- Describe the principles of interventional radiology including minimally invasive technique, image guidance modalities, and the multidisciplinary approach to patient care
- Explain indications, techniques, and complications of common vascular access procedures including central venous catheters and dialysis access management
- Understand the role of embolization, angioplasty, and thrombectomy in treating vascular pathology including hemorrhage, stenosis, and occlusion
- Describe oncologic interventions including tumor ablation and transarterial therapies for liver-directed treatment of primary and metastatic disease
- Apply appropriate imaging modalities for cancer staging and treatment response assessment using standardized criteria
- Integrate imaging into clinical decision-making through appropriate use criteria, multidisciplinary collaboration, and effective communication
I. Introduction to Interventional Radiology
Interventional radiology represents a distinct medical specialty that uses minimally invasive image-guided procedures to diagnose and treat diseases throughout the body. The fundamental principle underlying interventional radiology is that many conditions previously requiring open surgery can be treated through small percutaneous access points using imaging guidance to visualize and navigate to the target. This approach reduces patient morbidity, shortens hospital stays, decreases recovery time, and often provides equivalent or superior outcomes compared to surgical alternatives. The field continues to expand as new devices, techniques, and indications are developed.
Image guidance modalities enable precise targeting and real-time visualization during interventional procedures. Fluoroscopy provides continuous real-time imaging using x-rays and is essential for vascular procedures where contrast injection demonstrates vessel anatomy. CT guidance enables precise needle placement for biopsies and ablations of deep lesions by providing cross-sectional visualization of the target and surrounding structures. Ultrasound guidance offers real-time imaging without radiation, making it ideal for superficial lesions, vascular access, and procedures in pregnant patients. MRI guidance is used in specialized applications requiring superior soft tissue contrast or for procedures in patients with contraindications to other modalities.
Patient preparation for interventional procedures requires systematic evaluation of factors that influence procedural safety and success. Coagulation status including INR and platelet count must be assessed and corrected if necessary, with specific thresholds depending on the procedure and bleeding risk. Renal function guides contrast administration decisions and hydration protocols. Allergy history, particularly to contrast agents and latex, determines the need for premedication or alternative agents. NPO status depends on the procedure type and sedation requirements. Informed consent requires thorough discussion of the procedure, alternatives, risks, and expected outcomes.
Post-procedure care focuses on access site management and early detection of complications. Vascular access sites require hemostasis, which may be achieved through manual compression, closure devices, or both. Vital signs are monitored according to protocol, with frequency determined by the invasiveness of the procedure and patient stability. Potential complications vary by procedure type but may include bleeding, infection, contrast reaction, and organ-specific injuries. Discharge planning includes written instructions, activity restrictions, and follow-up arrangements to ensure continuity of care.
<image>Panel A: Interventional radiology suite with fluoroscopy, ultrasound, and monitoring equipment configured for vascular procedures. Panel B: CT-guided needle placement for biopsy of a deep retroperitoneal mass. Panel C: Ultrasound-guided central venous access with real-time visualization of needle entry. Panel D: Post-procedure compression following femoral artery access with activated clotting time monitoring.</image>
II. Vascular Access
Central venous catheters provide reliable access to the central circulation for medication administration, parenteral nutrition, and dialysis. Tunneled catheters, such as Hickman and Broviac types, have a subcutaneous segment that reduces infection risk and allows weeks to months of use. Non-tunneled catheters are placed directly into central veins and are appropriate for shorter-term access of days to weeks. Implantable ports consist of a reservoir placed subcutaneously with a catheter extending into the central circulation, providing long-term intermittent access with low infection rates and no external components. Peripherally inserted central catheters, or PICCs, are placed through peripheral arm veins and advanced to the cavoatrial junction for intermediate-duration access.
Dialysis access management represents a significant proportion of interventional radiology practice due to the large population of patients requiring hemodialysis. Tunneled dialysis catheters provide temporary access while native fistulas or synthetic grafts mature, or serve as permanent access in patients without other options. Fistulas and grafts require surveillance and intervention to maintain patency, with fistulograms used to map the access and identify stenoses. Angioplasty treats stenoses within the access circuit, while thrombectomy restores flow in acutely clotted accesses. Declotting procedures may combine mechanical thrombectomy, pharmacologic thrombolysis, and angioplasty of underlying stenoses.
Complications of central venous access require prompt recognition and appropriate management. Pneumothorax may result from inadvertent pleural puncture during subclavian or internal jugular access and may require observation or chest tube placement depending on size and symptoms. Arterial puncture is managed with compression in most cases but may require covered stent placement if significant arterial injury occurs. Catheter malposition requires repositioning or replacement to ensure the tip is appropriately located at the cavoatrial junction. Catheter-related bloodstream infection may be treated with antibiotics for salvageable catheters or may require catheter removal and replacement at a different site.
Best practices for central venous access emphasize the internal jugular vein as the preferred site due to lower complication rates compared to subclavian and femoral approaches. Real-time ultrasound guidance improves success rates and reduces complications compared to landmark-based techniques. Confirmation of appropriate catheter position is obtained through fluoroscopy during placement or post-procedure chest radiograph. Strict sterile technique, including maximum barrier precautions with full draping and gown, reduces the risk of catheter-related infection. Ongoing catheter care with standardized protocols for dressing changes and line access further minimizes infection risk.
<image>Panel A: Fluoroscopic image of tunneled dialysis catheter with tip at the cavoatrial junction. Panel B: Fistulogram demonstrating venous outflow stenosis amenable to angioplasty. Panel C: Chest radiograph showing malpositioned central catheter requiring repositioning. Panel D: Comparison of access site complication rates for internal jugular, subclavian, and femoral approaches.</image>
III. Vascular Interventions
Diagnostic angiography provides direct visualization of arterial and venous anatomy through catheter-directed contrast injection with fluoroscopic imaging. While largely replaced by CT angiography for diagnostic purposes, catheter angiography remains essential when intervention is planned or when higher spatial resolution is required. In gastrointestinal bleeding, angiography localizes the bleeding source and enables immediate embolization therapy. Trauma patients with arterial injury benefit from combined diagnostic and therapeutic angiography. Pre-operative vessel mapping for complex surgical procedures may require the resolution of catheter angiography.
Angioplasty and stenting treat arterial and venous stenoses by mechanically dilating the narrowed segment and, when indicated, placing a scaffold to maintain patency. Peripheral arterial disease affecting the iliac, femoral, and popliteal arteries is commonly treated with angioplasty and selective stenting based on lesion characteristics and response to balloon dilation. Renal artery stenosis may be treated with angioplasty and stenting for atherosclerotic disease or angioplasty alone for fibromuscular dysplasia. Venous stenoses, including those in dialysis access circuits and central veins, respond to angioplasty but often require repeated treatment due to elastic recoil and recurrence.
Embolization intentionally occludes blood vessels to stop bleeding, devascularize tumors, or treat vascular malformations. Embolic agents include coils that mechanically obstruct vessels, particles that occlude at the capillary level, and liquid agents that solidify within vessels. Gastrointestinal bleeding from peptic ulcer disease, diverticular disease, or tumor can be controlled with selective embolization. Trauma-related hemorrhage including splenic, hepatic, and pelvic bleeding is increasingly managed with embolization rather than surgery. Uterine artery embolization treats symptomatic fibroids by reducing blood supply and inducing infarction.
Thrombectomy and thrombolysis treat arterial and venous occlusions by removing or dissolving thrombus to restore flow. Mechanical thrombectomy devices physically extract or macerate clot, enabling rapid recanalization. Catheter-directed thrombolysis delivers fibrinolytic agents directly to the thrombus, maximizing local effect while minimizing systemic bleeding risk. Deep venous thrombosis may be treated with catheter-directed therapy to reduce post-thrombotic syndrome, particularly in iliofemoral DVT. Pulmonary embolism with right ventricular strain may be treated with catheter-directed therapy when systemic thrombolysis is contraindicated or has failed. Acute limb ischemia from arterial occlusion requires urgent revascularization with thrombectomy, thrombolysis, or both.
<image>Panel A: Selective angiogram demonstrating active extravasation from a gastroduodenal artery branch in upper GI bleeding. Panel B: Iliac artery angioplasty and stent placement for occlusive peripheral arterial disease. Panel C: Post-embolization angiogram showing successful coil occlusion of bleeding vessel with no residual extravasation. Panel D: Catheter-directed thrombolysis for iliofemoral deep venous thrombosis with before and after venograms.</image>
IV. Oncologic Interventions
Tumor ablation uses various energy sources to destroy tumor cells through extreme temperature changes or cellular membrane disruption. Radiofrequency ablation generates heat through electrical current flow from an electrode to dispersive grounding pads, achieving cell death through coagulative necrosis. Microwave ablation uses electromagnetic energy to heat tissue and offers advantages of larger ablation zones and less susceptibility to heat sink effects from adjacent blood vessels. Cryoablation freezes tissue through gas expansion in the probe tip, creating an ice ball that is visible on CT and MRI during the procedure. Irreversible electroporation uses electrical pulses to permanently disrupt cell membranes without thermal injury, preserving adjacent structures such as bile ducts and blood vessels.
Ablation indications span multiple organ systems and tumor types. Hepatocellular carcinoma in patients with cirrhosis who are not surgical candidates can be treated with ablation, which may also serve as a bridge to liver transplantation. Colorectal liver metastases may be ablated when limited in number and not amenable to resection. Small renal cell carcinomas are increasingly treated with ablation, particularly in patients with comorbidities or solitary kidneys. Lung tumors, particularly metastases, may be ablated when surgical resection is not feasible. Painful bone metastases that have failed radiation therapy can be treated with ablation for palliation.
Transarterial therapies deliver embolic and therapeutic agents directly to liver tumors through their arterial blood supply. Transarterial chemoembolization, or TACE, combines chemotherapy with embolization to maximize drug delivery while inducing ischemia. Drug-eluting bead TACE uses microspheres loaded with chemotherapeutic agents that elute slowly after embolization. Radioembolization, also termed selective internal radiation therapy or Y90, delivers radioactive microspheres that lodge in tumor microvasculature and deliver localized radiation. Bland embolization uses particles alone to induce ischemia and is used for hypervascular tumors and when chemotherapy or radiation is contraindicated.
Liver-directed therapy plays an important role in the multidisciplinary management of primary and metastatic liver tumors. Hepatocellular carcinoma is treated with transarterial therapies when beyond surgical or ablation criteria but still confined to the liver. Metastatic disease from colorectal cancer and neuroendocrine tumors may be treated with liver-directed therapy when disease is predominantly hepatic. Downstaging from initially unresectable to resectable status may be achieved with effective locoregional therapy. Combination of transarterial therapy with systemic agents, including immunotherapy, is an area of active investigation.
<image>Panel A: CT-guided microwave ablation probe placement within a hepatocellular carcinoma. Panel B: Post-ablation CT showing complete tumor coverage by the ablation zone with appropriate margins. Panel C: Angiogram during TACE showing tumor blush and subsequent embolization. Panel D: Y90 radioembolization treatment planning with segmental dose mapping on nuclear medicine imaging.</image>
V. Image-Guided Biopsy
Percutaneous biopsy enables tissue diagnosis without surgical exploration by using imaging guidance to precisely target lesions throughout the body. The indications include establishing a primary diagnosis in suspected malignancy, determining tumor type for treatment planning, evaluating treatment response, identifying infectious organisms in suspected abscess, and assessing the nature of diffuse organ disease. The minimally invasive approach reduces morbidity compared to surgical biopsy and provides tissue adequate for histologic diagnosis, immunohistochemistry, and increasingly for molecular and genetic analysis.
Guidance modality selection depends on lesion location, visibility, and the need for real-time visualization during the procedure. CT guidance is preferred for deep lesions in the chest, abdomen, and pelvis where the target and surrounding structures are clearly visualized. Ultrasound guidance is optimal for superficial lesions, provides real-time visualization during needle advancement, and avoids radiation exposure. Fluoroscopic guidance is used for bone lesions and some lung nodules where the target can be visualized. MRI guidance offers superior soft tissue contrast but is limited by equipment requirements and longer procedure times.
Biopsy technique varies based on the clinical question and tissue requirements. Fine needle aspiration using small-gauge needles yields cellular material for cytologic analysis and is useful for thyroid nodules and lymph nodes. Core needle biopsy using cutting needles provides tissue architecture for histologic analysis and is preferred when tissue structure is needed for diagnosis. The coaxial technique uses an outer introducer needle through which multiple core samples can be obtained without repeated passes through the body wall. Sample adequacy should be confirmed with on-site cytology or visual inspection before concluding the procedure.
Complications of percutaneous biopsy are generally minor but require recognition and management. Bleeding is the most common complication and is usually self-limited, though significant hemorrhage may require embolization or surgery. Pneumothorax occurs in approximately fifteen to twenty percent of transthoracic lung biopsies, with most cases small and requiring only observation. Tumor seeding along the needle tract is rare but is minimized by using coaxial technique and planning the tract to be included in subsequent surgical resection. Infection is uncommon with sterile technique but should be considered when biopsying potentially infected collections.
<image>Panel A: CT-guided core biopsy of a lung nodule with coaxial technique showing introducer and biopsy needle. Panel B: Ultrasound-guided fine needle aspiration of a thyroid nodule with real-time needle visualization. Panel C: Small post-biopsy pneumothorax on CT that was managed with observation. Panel D: Biopsy tract planning to ensure inclusion within anticipated surgical resection margin.</image>
VI. Drainage Procedures
Percutaneous abscess drainage is the treatment of choice for most accessible infected fluid collections, avoiding the morbidity of surgical exploration and drainage. Collections are localized with CT or ultrasound, and drainage catheters are placed using Seldinger or trocar techniques. Abdominal and pelvic abscesses, including postoperative collections, diverticular abscesses, and appendiceal abscesses, are routinely drained percutaneously. Transrectal and transgluteal approaches access deep pelvic collections that are not safely reachable through anterior routes. Ongoing catheter management includes irrigation, output monitoring, and imaging follow-up to assess resolution.
Biliary drainage provides decompression of obstructed bile ducts when endoscopic retrograde cholangiopancreatography is unsuccessful or not feasible. Percutaneous transhepatic cholangiography, or PTC, visualizes the biliary tree and guides catheter placement. External drainage alone may be used for initial decompression, with conversion to internal-external drainage allowing bile to drain both externally and internally into the duodenum. Biliary stent placement provides definitive palliation of malignant obstruction or serves as a bridge to surgery. Percutaneous approaches also enable stone extraction, stricture dilation, and access for cholangioscopy.
Nephrostomy provides urinary diversion when ureteral obstruction cannot be relieved by ureteral stent or when the urinary tract requires complete diversion. Obstructing ureteral calculi causing infection require urgent decompression to treat or prevent urosepsis. Malignant ureteral obstruction may be treated with nephrostomy alone or as a bridge to ureteral stent placement. Urinary fistulas and leaks may require nephrostomy to divert urine while healing occurs. Percutaneous nephrostomy also provides access for antegrade ureteral stent placement and percutaneous nephrolithotomy.
Thoracic drainage procedures address pleural fluid collections and pneumothorax. Small-bore pigtail catheters effectively drain simple pleural effusions and pneumothoraces with less patient discomfort than traditional large-bore chest tubes. Empyema may require larger catheters and adjunctive fibrinolytic therapy to break up loculations and promote complete drainage. Tunneled pleural catheters, such as the PleurX system, provide long-term drainage for recurrent malignant effusions, enabling outpatient management and potentially achieving pleurodesis. Image guidance ensures safe catheter placement, avoiding the lung parenchyma and intercostal vessels.
<image>Panel A: CT demonstrating percutaneous drainage catheter within a pelvic abscess with decrease in collection size. Panel B: Percutaneous transhepatic cholangiography showing biliary obstruction with internal-external drainage catheter placement. Panel C: Ultrasound-guided nephrostomy for obstructing ureteral calculus with associated pyonephrosis. Panel D: PleurX tunneled pleural catheter for recurrent malignant pleural effusion.</image>
VII. Oncologic Imaging Concepts
Staging imaging establishes the extent of malignant disease to guide treatment selection and provide prognostic information. The TNM staging system evaluates tumor size and local extent, lymph node involvement, and presence of distant metastases. Cross-sectional imaging with CT and MRI provides anatomic information about tumor size, local invasion, and nodal disease. PET/CT adds metabolic information that can identify involved lymph nodes that are normal in size and detect distant metastases that might be missed on anatomic imaging alone. Staging protocols are tailored to specific tumor types based on expected patterns of spread and the imaging modalities that best demonstrate disease.
Response assessment uses standardized criteria to evaluate treatment effect through changes in tumor size and appearance on imaging. Response Evaluation Criteria in Solid Tumors, or RECIST, measures target lesion diameters and classifies response as complete, partial, stable, or progressive based on percentage change. Modified RECIST, or mRECIST, is used for hepatocellular carcinoma and measures viable enhancing tumor rather than total tumor size, accounting for necrosis induced by locoregional therapy. The Lugano classification assesses lymphoma response using PET metabolic activity. Immune-related response criteria account for pseudoprogression that may occur early during immunotherapy before eventual response.
PET/CT using fluorodeoxyglucose, or FDG, provides metabolic imaging that complements anatomic evaluation for many malignancies. FDG uptake reflects glucose metabolism and is increased in most malignant tumors due to the Warburg effect of increased glycolysis. Standardized uptake value, or SUV, provides semi-quantitative assessment of uptake intensity for comparison between examinations. PET/CT is particularly valuable for staging and restaging lymphoma, lung cancer, and melanoma. Limitations include false-positive uptake in inflammatory conditions and false-negative results in tumors with low metabolic activity such as mucinous adenocarcinomas and some well-differentiated neuroendocrine tumors.
Tumor markers and imaging are used together for disease monitoring, with changes in markers prompting imaging evaluation and imaging findings guiding marker monitoring. Alpha-fetoprotein correlates with hepatocellular carcinoma burden and response to treatment. Carcinoembryonic antigen, or CEA, is used for colorectal cancer surveillance, with rising levels prompting imaging for recurrence. CA 19-9 elevations in pancreatic and biliary cancers may precede imaging-detectable recurrence. Prostate-specific antigen, or PSA, guides the use of multiparametric prostate MRI for tumor detection and staging.
<image>Panel A: Staging PET/CT for lung cancer showing primary tumor and metabolically active mediastinal lymph nodes. Panel B: RECIST response assessment demonstrating partial response with decrease in target lesion diameter. Panel C: Hepatocellular carcinoma mRECIST assessment showing complete response with no viable enhancing tumor after treatment. Panel D: Graph correlating tumor marker levels with imaging findings during treatment and surveillance.</image>
VIII. Nuclear Medicine
Common nuclear medicine studies provide functional information that complements anatomic imaging. Bone scintigraphy, or bone scan, uses technetium-labeled diphosphonates that accumulate in areas of increased bone turnover, detecting metastases, infection, and occult fractures. Ventilation-perfusion scanning evaluates for pulmonary embolism by comparing ventilation and perfusion patterns, with mismatched defects indicating embolic disease. Thyroid scintigraphy characterizes nodules as hot or cold based on radiotracer uptake and evaluates hyperthyroidism etiology. Hepatobiliary iminodiacetic acid, or HIDA, scanning evaluates for acute cholecystitis and biliary system patency.
PET imaging uses positron-emitting radiotracers that provide metabolic and functional information with higher resolution than conventional nuclear medicine. FDG remains the most widely used PET tracer and is valuable for oncologic staging and restaging. Prostate-specific membrane antigen, or PSMA, PET provides highly sensitive detection of prostate cancer, particularly biochemical recurrence. Gallium-68 DOTATATE PET detects somatostatin receptor-expressing neuroendocrine tumors with greater sensitivity than conventional imaging. Amyloid PET imaging supports the diagnosis of Alzheimer disease by demonstrating brain amyloid deposition.
Therapeutic nuclear medicine delivers targeted radiation through systemically administered radiopharmaceuticals. Iodine-131 treats thyroid cancer by accumulating in and destroying thyroid tissue, both benign and malignant. Yttrium-90 microspheres deliver selective internal radiation therapy to liver tumors through hepatic artery administration. Lutetium-177 DOTATATE treats somatostatin receptor-positive neuroendocrine tumors with targeted radionuclide therapy. Radium-223 treats bone metastases in castration-resistant prostate cancer by incorporating into areas of high bone turnover. These therapies require careful patient selection, dosimetry, and radiation safety precautions.
Radiation safety in nuclear medicine requires attention to patient preparation, environmental contamination, and radiation exposure to staff and family. Patients receive specific instructions about hydration, medication timing, and interaction with family members depending on the administered radiopharmaceutical. Therapeutic administrations, particularly iodine-131, may require hospitalization until radiation levels decrease to safe levels for discharge. Staff members use time, distance, and shielding to minimize occupational exposure. Pregnancy is a contraindication to most nuclear medicine procedures due to fetal radiation exposure.
<image>Panel A: Bone scan demonstrating multiple skeletal metastases with increased uptake in the spine, ribs, and pelvis. Panel B: Ventilation-perfusion scan showing mismatched defects consistent with pulmonary embolism. Panel C: PSMA PET showing prostate cancer recurrence in pelvic lymph nodes. Panel D: Treatment planning for Y90 radioembolization with dose calculation and safety assessment.</image>
IX. Special Populations and Considerations
Imaging in pregnancy requires balancing diagnostic accuracy against potential fetal radiation exposure and contrast agent safety. Ultrasound is the first-line imaging modality in pregnancy for most indications because it does not use ionizing radiation. MRI without gadolinium is considered safe throughout pregnancy and provides excellent soft tissue evaluation for abdominal and pelvic pathology. CT should be performed when clinically indicated for maternal diagnosis, as the radiation dose from most CT examinations is below thresholds for deterministic fetal effects. Gadolinium-based contrast agents cross the placenta and should be avoided unless the diagnostic information is essential and cannot be obtained otherwise.
Pediatric imaging considerations emphasize radiation dose reduction while maintaining diagnostic image quality. The Image Gently campaign has raised awareness of pediatric radiation issues and promoted dose optimization. Child-sized CT protocols reduce tube current and voltage appropriate for body size, and iterative reconstruction techniques enable further dose reduction. Ultrasound and MRI should be used preferentially when they can provide the diagnostic information needed. Sedation may be required for MRI in young children but carries its own risks and requires appropriate monitoring and recovery protocols.
Contrast administration in renal impairment requires assessment of both iodinated and gadolinium-based agents. Iodinated contrast for CT is generally safe in patients with GFR greater than thirty, with hydration recommended for patients with moderate renal impairment. Patients with GFR below thirty require careful consideration of the risk-benefit ratio and may benefit from alternative imaging modalities. Gadolinium-based contrast agents carry a risk of nephrogenic systemic fibrosis in patients with severe renal impairment, and group II gadolinium agents are preferred in patients with reduced renal function. Dialysis does not prevent nephrogenic systemic fibrosis, and gadolinium should be avoided or used with caution in dialysis-dependent patients.
Contrast allergy management depends on the severity of prior reactions and the clinical necessity of contrast-enhanced imaging. Patients with prior mild reactions such as urticaria can often undergo contrast-enhanced imaging with corticosteroid and antihistamine premedication. Prior severe reactions including anaphylaxis require careful consideration of alternatives, and if contrast is essential, premedication protocols should be followed with preparation for emergency treatment. Emergency medications and equipment must be immediately available whenever contrast agents are administered. Alternative imaging modalities that do not require the offending contrast agent should be considered when diagnostic information can be obtained without contrast.
<image>Panel A: Ultrasound of appendicitis in a pregnant patient avoiding radiation exposure while maintaining diagnostic accuracy. Panel B: Pediatric CT protocol comparison showing reduced radiation dose with maintained image quality. Panel C: Algorithm for contrast administration decision-making based on renal function. Panel D: Contrast reaction premedication protocol for patients with prior allergic reactions.</image>
X. Integrating Imaging in Clinical Care
Multidisciplinary conferences provide a forum for integrating imaging findings into clinical decision-making through collaborative discussion among specialists. Tumor boards bring together surgeons, medical oncologists, radiation oncologists, pathologists, and radiologists to review complex cancer cases and develop consensus treatment plans. Radiology representation ensures that imaging findings are accurately presented and that the imaging implications of treatment decisions are considered. These conferences improve care quality by ensuring that all relevant expertise contributes to patient management and that treatment recommendations are aligned across specialties.
Appropriate use criteria guide imaging selection to maximize diagnostic value while minimizing unnecessary studies. The American College of Radiology Appropriateness Criteria provide evidence-based recommendations rating the appropriateness of imaging options for specific clinical scenarios. Clinical decision support systems integrated into electronic health records can prompt ordering physicians when selected imaging may not be appropriate and suggest alternatives. Consultation with radiologists for complex cases ensures that the optimal imaging approach is selected. These tools reduce low-value imaging, contain costs, and minimize radiation exposure.
Effective communication between radiologists and ordering clinicians ensures that imaging findings translate into appropriate patient care. Clinical history provided with imaging orders should include the specific clinical question, relevant symptoms and physical findings, and pertinent prior imaging. Radiology reports should directly address the clinical question and provide clear, actionable impressions. Critical findings require direct verbal communication to ensure timely intervention. Recommendation tracking systems help ensure that imaging follow-up recommendations are completed and not lost to follow-up.
Quality and safety programs in radiology ensure continuous improvement in imaging practice. Radiation dose monitoring tracks exposure from CT and fluoroscopy to identify opportunities for optimization. Contrast reaction rates are monitored and analyzed to identify risk factors and improve prevention. Report turnaround time metrics ensure timely communication of imaging results. Peer review processes provide feedback on interpretive accuracy and identify opportunities for individual and system improvement. Commitment to quality and safety improves patient outcomes and maintains trust in the imaging enterprise.
<image>Panel A: Multidisciplinary tumor board meeting with radiology images displayed for collaborative case discussion. Panel B: Clinical decision support alert suggesting alternative imaging for a low-value study order. Panel C: Structured workflow for critical result communication including notification, acknowledgment, and documentation. Panel D: Quality dashboard displaying key radiology performance metrics including dose, turnaround time, and peer review results.</image>
Summary
Interventional radiology provides minimally invasive image-guided treatment for a wide range of conditions using fluoroscopy, CT, ultrasound, and MRI guidance. Patient preparation includes assessment of coagulation, renal function, allergies, and informed consent. Post-procedure care focuses on access site management and complication detection.
Vascular access procedures include tunneled and non-tunneled central catheters, ports, PICCs, and dialysis access management. Vascular interventions include diagnostic angiography, angioplasty and stenting for stenotic disease, embolization for hemorrhage and tumors, and thrombectomy for occlusive disease. The internal jugular vein is preferred for central access with ultrasound guidance.
Oncologic interventions include tumor ablation using radiofrequency, microwave, and cryoablation techniques, and transarterial therapies including TACE and Y90 radioembolization for liver-directed treatment. Image-guided biopsy provides tissue diagnosis with CT, ultrasound, or fluoroscopic guidance. Drainage procedures treat abscesses, biliary obstruction, and urinary obstruction percutaneously.
Staging imaging uses CT, MRI, and PET/CT tailored to tumor type. Response assessment follows RECIST, mRECIST, and other standardized criteria. Nuclear medicine provides functional imaging and targeted radionuclide therapy. Special populations including pregnant patients, pediatric patients, and those with renal impairment or contrast allergies require modified approaches. Multidisciplinary integration and appropriate use criteria optimize the contribution of imaging to patient care.
Key Terms
Embolization: Intentional occlusion of blood vessels to stop hemorrhage, devascularize tumors, or treat vascular malformations, using agents including coils, particles, and liquid embolic materials.
TACE: Transarterial chemoembolization, a liver-directed therapy delivering chemotherapy combined with embolic particles through the hepatic artery to treat hepatocellular carcinoma and metastatic disease.
RFA: Radiofrequency ablation, a technique using electrical current to generate heat and induce coagulative necrosis for tumor destruction.
PTC: Percutaneous transhepatic cholangiography, an interventional procedure providing access to the biliary system for drainage, stent placement, or stone extraction.
RECIST: Response Evaluation Criteria in Solid Tumors, a standardized system for measuring tumor response to treatment based on changes in lesion diameter.
SUV: Standardized uptake value, a semi-quantitative measure of radiotracer uptake on PET imaging used to assess metabolic activity and compare studies.
ALARA: As Low As Reasonably Achievable, the radiation protection principle guiding imaging practice to minimize exposure while maintaining diagnostic quality.
CDS: Clinical decision support, electronic systems integrated with ordering workflows to guide appropriate imaging selection based on evidence-based criteria.
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