Customizing Contrast Injection for Body MDCT: Algorithmic Approach Customizing Contrast Injection for Body MDCT: Algorithmic Approach Lincoln L. Berland, M.D., F.A.C.R. Lincoln L. Berland, M.D., F.A.C.R. Lincoln L. Berland, M.D., F.A.C.R. University of Alabama at Birmingham University of Alabama University of Alabama at at Birmingham Birmingham
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Customizing Contrast Injection for Body MDCT: Algorithmic … · 2013-12-09 · Contrast Volume 98 mL 140 mL 175 mL 200 mL* Contrast Volume 55 mL 75 mL 90 mL Weight Body CT Based
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Customizing Contrast Injection for Body MDCT:
Algorithmic Approach
Customizing Contrast Injection for Body MDCT:
Algorithmic Approach
Lincoln L. Berland, M.D., F.A.C.R.Lincoln L. Berland, M.D., F.A.C.R.Lincoln L. Berland, M.D., F.A.C.R.
University of Alabamaat Birmingham
University of AlabamaUniversity of Alabamaatat BirminghamBirmingham
Before Contrast
Prep and Hydration
• Hydration single most important factor:To get adequate collecting system fillingTo limit nephrotoxicity
• Don't keep patient NPO (clear liquids in am)• Lots of water prior to scan
Intravenous Contrast Parameters
• Contrast or not?• Route - IV arm, central line, hand, foot• Concentration• Volume• Rate• Saline chaser• Fixed, bolus tracking, test bolus
Principles of Intravenous Contrast Dynamics
General - Iodine Dose
• If increase dose of Iodine, but inject within same duration:
Increases peak enhancementDoes not change time at which peak occurs
• How to achieve this:Increase contrast concentration, orIncrease injection rate, maintain injection duration (more contrast volume)
Iodine Concentration Selection
• Higher concentration: can inject more Iodine for a specific volume/second
Equivalent to increasing injection rate if you don’t increase concentration
• With higher concentration, can decrease the volume injection rate for given Iodineinjection rate
• Therefore, 350-400 mg I/mL preferred over 300 mg I/mL
Aorta, Liver by Rate
• If increase injection rate, but keep Iodine dose constant:
Aortic enhancement peak increases continuously with rateLiver enhancement peak levels off above 1.5 mL/sec
Aorta, Liver Enhancement
• MYTH:Can decrease contrast dose for liver scan by increasing injection rate
• TRUTH:Can decrease contrast dose for CTA by increasing injection rate
Injection Duration
• TIME to peak aortic and liver enhancement depends most strongly on injection duration
• Peak enhancement usually occurs shortly after injection completed
Injection Duration
• MYTH:For body scans, can use fixed scan delay regardless of injection rate
• TRUTH:Enhancement curves vary greatly by patientUse bolus tracking for arterial studiesFixed delay (by duration) usually OK for liver,etc.
Scan Delay
• MYTH: Faster scanner (e.g. 64 vs. 4-slice), shorter delay to scanning
• TRUTH: Faster scanner, longer delay to begin scanning
Peak doesn’t change, but more likely to finish scan before peak occursDownslope of enhancement not as fast as upslope, so better to scan a little late rather than early
Patient-Specific Factors
Patient Weight - Enhancement
• Hepatic and arterial enhancement are proportional to Iodine dose administered and inversely proportional to weight
• Time to the enhancement peak is affected little by weight
• Therefore, Iodine dose should be increased proportional to weight
Cardiac Output - Aorta
• As cardiac output decreases, delay to peak increases
• MYTH: As cardiac output decreases, enhancement decreases
• Loose leaf handbooks (cookbooks) created• One customized cookbook placed at each
scanner• Each cookbook is specific for scanner type
and concentration of contrast material used• Master reference cookbooks placed in
radiology reading room
Indications:Cirrhosis: evaluating for HCC and portal hypertension.Pre-Intervention planning: for TIPS, chemoembolization, embolization, ablation.Cholangiocarcinoma.Characterize unknown liver lesion.Notes, modifications:Should be done on 40 or 64-slice scanners, if possible, because 3D rendering is usually needed and these provide better image qualityPelvis should be performed if concern about pelvic metastasis or if known prior important pelvic abnormalityIf following up vascular metastases that are known to be seen best on portal venous phase, perform routine abdomen protocol.
Oral contrast No NoRectal contrast No NoIV contrast Š iodine conc. (mgI/mL) 350-370
Iodine dose (gI), Volume and Flow Rate
52 gI for 60-90 kg patient. Adjust proportionally for weight. See
"Contrast Cookbook"This is a higher dose than routine protocols to optimize post-
processing and segmentationSaline flush - volume (mL) 50 If no dual injector, increase contrast dose by 10 mLSaline flush - flow rate (mL/s) Same as contrast injection rate
Scan delayTrigger at 150 HU in aorta plus 15
seconds 45 seconds post-trigger 3 minutes post-triggerHAP slightly later than routine AP. Change delay to 10 minute for
cholangiocarcinomaAcquisition Parameters
Scout PALateral scanogram can help see spinal compressions; post-scan
scanogram serves as a one-shot IVPPatient position Supine, feet first Supine, feet first Supine, feet first Supine, feet first
Scan range Diaphragm to iliac crest Diaphragm to iliac crestDiaphragm to iliac crest or
greater trochanter LiverScanning direction Out Out Out OutAcquisition field of view Full patient width Full patient width Full patient width Full patient widthTube voltage (kVp) 120 120 120 120 Can use 140 kVp for large patientsTube load (mAs) 170 to 200 250 to 300 250 to 300 170 to 200 Consider automated dose modulationGantry rotation time (s) 0.5 0.5 0.5 0.5 Consider 0.75 for obese patients
Detector configuration (mm) 40 x 0.625 or 64 x 0.625 40 x 0.625 or 64 x 0.62540 x 0.625 or 64 x
0.62532 x 1.25 or 64 x 0.625
Pitch 1 1 1 1Scanner automatically assigns optimal pitch based on approximate
selection.Reconstruction ParametersAxial reconstruction (mm) 5.0 x 5.0 5.0 x 5.0 5.0 x 5.0 5.0 x 5.0Thin section axial for 3D/MPR (mm) 1.3 x 0.7 up to 2.0 x 1.0 1.3 x 0.7 up to 2.0 x 1.0
Coronal reconstruction (mm) 3.0 Š 4.0 x 3.0 3.0 Š 4.0 x 3.0
Coronal and sagittal reconstructions should be performed routinely on HAP and PVP. Thick slab MIPs and/or sagittal MIPs may
replace coronal and sagittal MPRs.
Recon filter kernel B or C B or C B or C
Filter A helpful for very obese patients (less noisy images). Filter B if lower mAs chosen (more noise than Filter A, but appropriate for
average patient). Filter C increases spatial resolution, but also increases noise.
Recon field of view Evolving Evolving Evolving
Liver Four-Phase (Abdomen or Abdomen/Pelvis): 40-slice, 64-slice
Indications:Pancreatic mass known or suspected.Pancreatic carcinoma follow-up after treatment (surgery, XRT, chemotherapy) if pancreatic phase needed (see Exclusions, Notes below).Painless jaundice.Chronic pancreatitis vs. pancreatic mass.Acute pancreatitis > age 50 to rule out mass as etiology of pancreatitis.Exclusions:Acute pancreatitis < age 50 (Routine protocol).Known chronic pancreatitis to evaluate complications (Routine protocol).Known pancreatic adenocarcinoma recurrence or metastasis if well seen on PVP (Routine protocol).Pancreatic neuroendocrine tumor follow-up after treatment (RCC, Vascular Cancer FU protocol).Notes, modifications:Should be done on 40 or 64-slice scanners, if possible, because 3D rendering is usually needed and these provide better image quality.Pelvis should be performed if concern about pelvic metastasis or if known prior important pelvic abnormality.If following known unresectable pancreatic carcinoma, including with metastases, a routine abdomen or abdomen/pelvis may suffice.Routine examination may also be done for chronic pancreatitis to evaluate complications, acute pancreatitis < age 50, or pancreatitis reassessment.Contrast Unenhanced Phase (UP) Pancreatic Phase (PP) Portal Venous Phase (PVP) Comments
Oral contrast
Water or VolumenTM 500 mL to tolerance plus 250 mL
water on tableRectal contrast NoIV contrast Š iodine conc. (mgI/mL) 350-370
Iodine dose (gI), Volume and Flow Rate
52 gI for 60-90 kg patient. Adjust proportionally for weight. See
"Contrast Cookbook"
This is a higher dose than routine protocols to optimize post-processing and segmentation.
Prefer higher injection rate, if possible, up to 5 mL/sec.
Saline flush - volume (mL) 30If no dual injector, increase contrast dose by 10
mLSaline flush - flow rate (mL/s) Same as contrast injection rate
Lateral scanogram can help see spinal compressions; post-scan scanogram serves as a
one-shot IVPPatient position Supine, feet first Supine, feet first Supine, feet first
Scan range Diaphragm to iliac crest Diaphragm to iliac crestDiaphragm to iliac crest or greater
trochanterScanning direction Out Out OutAcquisition field of view Full patient width Full patient width Full patient widthTube voltage (kVp) 120 120 120 Can use 140 kVp for large patientsTube load (mAs) 170 to 200 250 to 300 250 to 300 Consider automated dose modulationGantry rotation time (s) 0.5 0.5 0.5 Consider 0.75 for obese patients
Detector configuration (mm) 40 x 0.625 or 64 x 0.625 40 x 0.625 or 64 x 0.62540 x 0.625 or 64 x
based on approximate selection.Reconstruction ParametersAxial reconstruction (mm) 5.0 x 5.0 2.0 x 2.0 4.0 x 3.0
Thin section axial for 3D/MPR (mm) 1.3 x 0.7 up to 2.0 x 1.0 1.3 x 0.7 up to 2.0 x 1.0
Perform 3D volume and curved planar reformatting. Note: qualifies for additional post-
processing coding
Coronal reconstruction (mm) 3.0 Š 4.0 x 3.0 3.0 Š 4.0 x 3.0
Coronal reconstructions should be performed on both the Pancreatic and Portal Venous phases. Thick slab MIPs and/or sagittal MIPs may be considered as a replacement for coronal and
sagittal MPRs.
Recon filter kernel B or C B or CFilter A helpful for very obese patients. Filter B if
lower mAs chosenRecon field of view Evolving Evolving
Pancreas (Abdomen or Abdomen/Pelvis): 40-slice, 64-slice
Renal Mass Pre-Intervention
Renal Mass Pre-intervention
• Indications:Prepare for nephron-sparing surgery or ablation