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GENERAL COMMENTS REGARDING CONTRAST ENHANCEMENT:

ADVANTAGES:

  • Iodinated IV contrast media (ICM) is deemed valuable in CT examinations performed in the setting of neoplastic, infectious and inflammatory conditions or when vascular etiologies are suspected. Abnormalities are more conspicuous due to contrast enhancement.
  • CT angiography studies utilize a higher rate of contrast administration, typically around 4cc per second, and shorter scan delay to optimize vessel opacification to allow for luminal assessment. In these cases, the ‘earlier’ scanning to evaluate the vessels may render solid visceral enhancement suboptimal for lesion detection.

DISADVANTAGES:

  • Instances where IV contrast is considered a potential hindrance include urolithiasis because the urolith may be obscured by intravascular or excreted contrast in the urinary system. A similar consideration applies to the assessment of sialolithiasis.
  • Another common instance when ICM is avoided is when intracranial hemorrhage is suspected. This relates to the fact that acute hemorrhage and parenchymal/meningeal enhancement both appear hyperdense and therefore can be confused with one another.
  • Iodinated contrast for diagnostic CT exams may also be considered undesirable when administered before a therapeutic or diagnostic dose of radio-iodine as it can adversely affect thyroid uptake of these radio-isotopes and thereby detract from the diagnostic or therapeutic goals.

2 relevant issues related to the administration of iodinated contrast material are allergic reaction and contrast induced nephropathy/nephrotoxicity.

When prescribing a radiologic study utilizing ICM, the ordering physician/service should arrange the following prior to the scheduled exam as indicated.

BUN/Creatinine

  • Required within 30 days prior to the scheduled ICM injection in :
    • All patients age 60 and over.
    • Patients at risk of developing contrast induced nephropathy. May contact Radiology Department for full details.

Allergy premedication:

Our recommendations are taken from the ACR contrast manual (can be viewed by clicking here). The patients who primarily receive premedication are those who have had a prior reaction to IV contrast. The old IV contrast given many years ago for IVP studies was more allergenic than what is currently used today. A patient history of shellfish allergy is no longer considered a significant risk for an adverse contrast reaction, although it is known that patients who have food/environmental allergies or atopy do have a slightly higher risk of a reaction than patients with no such history. The typical outpatient premedication is:

Prednisone, 50mg by mouth, three doses taken 13 hrs, 7 hrs, and 1 hr before IV contrast is given. 50 mg of Diphyenhydramine (Benadryl®) is also given 1 hr prior to contrast as well (by mouth usually but can be given IV)

In the emergent setting where contrast must be given without the above preparation strategy, IV steroids are used although this is less desirable. Despite IV route these steroids should be given 4 hours prior to the study to have an effect. 50 mg IV diphenhydramine should also be given 1 hr prior to contrast. Examples of IV steroid regimens (given at minimum 4 hours before the IV contrast and given every 4 hours until contrast is given) :

Methylprednisolone (Solu-Medrol®) 40 mg

Hydrocortisone (Solu-Cortef®) 200mg

Dexamethasone (Decadron®) 7.5 mg

 

The following is a review of commonly ordered CT scans and their indications:

 

CT EXAM CONTRAST INDICATIONS DESCRIPTION Preparation
BODY
Abdomen or A/P Unenhanced [includes “stone” protocol] NO Patients who are allergic to iodinated contrast media who require study for Abdominal pain. Renal stone protocol Oral contrast can be utilized except for renal stone protocol NPO x 4 hrs
Abdomen or A/P with IV contrast INTRAVENOUS (IV) Abdominal distention, pain (appendicitis, pancreatitis, infection, diverticulitis, colitis) metastatic disease, AAA Trauma, fever. Oral contrast typically administered. Imaged in the venous phase to optimally visualize the solid viscera. NPO x 4 hrs, Screen for allergy and risk of contrast induced nephropathy (CIN)
Abdomen with and without (“Biphasic”) With and Without IV Contrast metastases, possible urolith vs inflammatory process, fatty liver, hemochromatosis Precontrast to assess for calcification in lesions or in urinary system. Postcontrast to assess solid viscera during the venous phase NPO x 4 hrs, Screen for allergy and risk of CIN
Abdomen or A/P with & w/o IV contrast (“Triphasic”) With and Without IV Contrast characterize liver, pancreas, adrenal or renal tumors/lesions. Surveillance in chronic liver disease. [“liver mass” vs “pancreatic mass” vs “adrenal mass” vs “renal mass” protocol] Precontrast imaging + arterial, venous and delayed phase post-contrast imaging. Delayed imaing for adrenal at 10-12 minutes to calculate washout. NPO x 4 hrs, Screen for allergy and risk of CIN
Pelvis unenhanced (soft tissue and/or bony structures) NO trauma, pelvic fracture, post brachytherapy seed placement. Bleed. oral contrast useful when assessing for adenopathy, tumor, abscess or abnormalities of the bowel. Also to assess bony pelvis. NPO x 4 hrs
Pelvis with IV contrast INTRAVENOUS (IV) pelvic abscess, bleed. IV contrast aids in viscera assessment, abscess. Can be with or without oral contrast. NPO x 4 hrs, Screen for allergy and risk of CIN
CT Enterography INTRAVENOUS (IV) Suspect inflammatory bowel disease, small bowel neoplasm, celiac disease, unexplained anemia similar to A/P with but timing of enhancement to optimize bowel wall enhancement + oral H2O to allow for visualization of bowel mucosa NPO x 4 hrs, Screen for allergy and risk of CIN
CT Urography INTRAVENOUS (IV) Hematuria, kidney stone vs mass/urothelial lesion evaluation Exam to evaluate for lesions/pathology of the urinary system with later delayed series to assess urothelium. NPO x 4 hrs, Screen for allergy and risk of CIN
CT Angiogram (CTA) Abdomen or A/P INTRAVENOUS (IV) aortic, mesenteric or renal artery abnormalities, stent graft pre/post op evaluation. Exam used to evaluate the arterial structures of the abdomen/pelvis. NPO x 4 hrs, Screen for allergy and risk of CIN
CT Angiogram (CTA) A/P with runoff with IV contrast INTRAVENOUS (IV) Pre-surgical workup for interventional procedures, evaluation of bypass grafts, aneurysms Exam used to evaluate the arterial structures of the abdomen, pelvis and bilateral lower extremities. NPO x 4 hrs, Screen for allergy and risk of CIN
Chest unenhanced NO lung nodule, abnormal CXR, effusion, rib fx, acute or chronic lung disease (HRCT series included) to evaluate the lung parenchyma, pleural spaces, mediastinal structures
Chest with IV contrast INTRAVENOUS (IV) lung nodule, abnormal CXR, effusion, medistinal/hilar abnormality allows for better visualization of mediastinal and hilar structures or lesions located centrally in the lungs NPO x 4 hrs, Screen for allergy and risk of CIN
Chest CTA for pulm embolism INTRAVENOUS (IV) pulmonary embolus, abnormal Ddimer, SOB, CP IV contrast administered at higher rate to evaluate the Pulmonary Arteries for embolus NPO x 4 hrs, Screen for allergy and risk of CIN
Chest CTA (aortic/artrerial abnormality) INTRAVENOUS (IV) chest pain, Aortic aneurysm, dissection, intramural hematoma, penetrating aortic ulcer IV contrast administered at higher rate to evaluate the thoracic aorta. Precontrast series also included to assess for intramural hematoma NPO x 4 hrs, Screen for allergy and risk of CIN
CTA Chest (coronary) INTRAVENOUS (IV) Evaluation for coronary artery disease evaluate coronary artery anatomy, stenosis . NPO x 4 hrs, Screen for allergy and risk of CIN
CT venogram (upper extremity/SVC) INTRAVENOUS (IV) Venous thrombus, compression, injury. Exam to assess larger upper extremity veins and the SVC. Alternative to MR venography. For extremity, must use an adequate gauge ipsalateral IV catheter with constrast followed by bolus of saline. NPO x 4 hrs, Screen for allergy and risk of CIN
NEURO CONTRAST INDICATIONS DESCRIPTION Preparation
Brain(head) unenhanced NO Headache, CVA, trauma, bleed, Exam of the head to evaluate all internal and external structures of the head.
Brain(head) with IV contrast INTRAVENOUS (IV) Mass, seizures, tumor, infection, MS Should include both pre and post-contrast series. NPO x 4 hrs, Screen for allergy and risk of CIN
Sinuses unenhanced NO acute/chronic sinus disease Exam of the frontal sinuses through the maxillary sinuses.
Sinuses with IV contrast INTRAVENOUS (IV) infection, mass, acute/chronic sinus disease Exam of the frontal sinuses through the maxillary sinuses. NPO x 4 hrs, Screen for allergy and risk of CIN
Orbits unenhanced NO trauma assess to bony orbit and the intraorbital structures
Orbits with IV contrast INTRAVENOUS (IV) mass, infection, trauma assess to bony orbit and the intraorbital structures NPO x 4 hrs, Screen for allergy and risk of CIN
Facial bones unenhanced NO trauma Exam of the Facial bones from the tip of the mandible through the frontal sinuses.
Facial bones with IV contrast INTRAVENOUS (IV) trauma, mass, infection Exam of the Facial bones from the tip of the mandible through the frontal sinuses. NPO x 4 hrs, Screen for allergy and risk of CIN
Temporal bones/IAC unenhanced NO evaluation of middle and inner ear Exam of the Temporal bones / Internal Auditory Canal scan from the mastoid tip through the temporal bone.
Temporal bones/IAC with IV contrast INTRAVENOUS (IV) evaluation of middle and inner ear disorders, mass, infection Exam of the Temporal bones / Internal Auditory Canal scan from the mastoid tip through the temporal bone. NPO x 4 hrs, Screen for allergy and risk of CIN
Pituitary INTRAVENOUS (IV) evaluation of Pituitary when MRI is not possible. Exam of the Pituitary from 10mm in front of the Cella to 10mm behind the Cella. This exam can be done with or without IV contrast. NPO x 4 hrs, Screen for allergy and risk of CIN
Neck w/o IV contrast tumor/mass/ infection when IV contrast precluded. Sialolith or assessing calcification. Exam for the evaluations of the soft tissue structures of the neck.
Neck with IV contrast INTRAVENOUS (IV) tumor, mass, infection Exam for the evaluations of the soft tissue structures of the neck. NPO x 4 hrs, Screen for allergy and risk of CIN
CTA Head(Circle of Willis) with IV contrast INTRAVENOUS (IV) Evaluation of the Circle of Willis, r/o-evaluate aneurysms Exam used to evaluate the arteries of the head. This exam is ordered with IV contrast . NPO x 4 hrs, Screen for allergy and risk of CIN
CTA Neck(Carotid Arteries) with IV contrast INTRAVENOUS (IV) Evaluation of Carotid arteries, great vessels coming off of the aortic arch, pre-CABG Exam used to evaluate the aortic arch and and the arteries of the neck. This exam is ordered with IV contrast . NPO x 4 hrs, Screen for allergy and risk of CIN
CT Venogram (intracranial) INTRAVENOUS (IV) Dural sinus thrombosis, dural AV fistula. Exam to assess the dural venous sinuses for patency. Alternative to MR venography. NPO x 4 hrs, Screen for allergy and risk of CIN
MUSCULOSKELETAL CONTRAST INDICATIONS DESCRIPTION Preparation
Myelogram *INTRATHECAL* contrast myelopathy, radiculopathy, neck/back pain. ordered for the Cervical, Thoracic and/or Lumbar spine to improve visualization of cord and nerve roots. Requires fluoroscopically guided lumbar puncture to administer contrast NPO x 4 hrs. withhold anticoagulants, Screen for allergy and risk of CIN
Cervical Spine with IV contrast INTRAVENOUS (IV) infection, collection, tumor/mass assess bony and soft tissues structures of the cervical spine. NPO x 4 hrs, Screen for allergy and risk of CIN
Cervical Spine unenhanced NO trauma, pain, degenerative disease, bony lesions assess bony and soft tissues structures of the cervical spine although soft tissue assessment better with IV contrast.
Thoracic Spine with IV contrast INTRAVENOUS (IV) infection, collection, tumor/mass assess bony and soft tissues structures of the thoracic spine. NPO x 4 hrs, Screen for allergy and risk of CIN
Thoracic Spine unenhanced NO trauma, pain, degenerative disease, bony lesions assess bony and soft tissues structures of the thoracic spine, although soft tissue assessment better with IV contrast.
Lumbar Spine with IV contrast INTRAVENOUS (IV) infection, collection, tumor/mass assess bony and soft tissues structures of the lumbar spine. NPO x 4 hrs, Screen for allergy and risk of CIN
Lumbar Spine unenhanced NO trauma, pain, degenerative disease, bony lesions assess bony and soft tissues structures of the lumbar spine, although soft tissue assessment better with IV contrast.
Upper Extremity bone/joint unenhanced NO pain, equivocal XR findings, trauma, malalignment, arthritis, bony lesions, foreign body. ** can provide better definition of cortical bone than MRI. MRI allows for better assessment of the soft tissue structures and the bone marrow. Exam ordered by area of interest: shoulder, humerus, elbow, forearm, wrist, hand.
Upper Extremity enhanced INTRAVENOUS (IV) mass, infection, radiographically occult pathology particularly of the soft tissue including synovial processess. **can provide better definition of cortical bone than MRI. MRI allows for better assessment of the soft tissue structures and the bone marrow. Exam ordered by area of interest: shoulder, humerus, elbow, forearm, wrist, hand. NPO x 4 hrs, Screen for allergy and risk of CIN
Shoulder arthrogram *Intra-articular* contrast rotator cuff tear, labral tear, intraarticular biceps tendon abnormality, cartilage defect/joint body Exam used to evaluate the structures of the shoulder when MR arthrogram is precluded. Requires fluoroscopically guided injection to administer contrast. NPO x 4 hrs. withhold anticoagulants, Screen for allergy and risk of CIN
Arthrogram (other joint in upper or lower extremity) *Intra-articular* contrast can aid in assessment of intra-articular structures, loose bodies. Utilized with MR arthrogram is precluded. Order as Hip, knee, ankle, etc. Requires fluoroscopically guided injection to administer contrast. NPO x 4 hrs. withhold anticoagulants, Screen for allergy and risk of CIN
Lower Extremity bone/joint unenhanced NO pain, equivocal XR findings, trauma, malalignment, arthritis, bony lesions, foreign body. **can provide better definition of cortical bone than MRI. MRI allows for better assessment of the soft tissue structures and the bone marrow. Exam ordered by area of interest: Hip, femur, knee, ankle, foot.
Lower Extremity with IV contrast INTRAVENOUS (IV) mass, infection, radiographically occult pathology particularly of the soft tissue including synovial processess. **can provide better definition of cortical bone than MRI. MRI allows for better assessment of the soft tissue structures and the bone marrow. Exam ordered by area of interest: Hip, femur, knee, ankle, foot. NPO x 4 hrs, Screen for allergy and risk of CIN