What information should be annotated for T2 (Transverse Relaxation Time) mapping, cardiac MRI (Magnetic Resonance Imaging), and Liver MRI (Magnetic Resonance Imaging) iron load?

Annotating Doctor's Comments/Indications for T2 Mapping, Cardiac MRI, and Liver MRI Iron Load

When ordering these studies, specify the exact MRI method (R2, T2, or R2), field strength, and clinical indication to ensure proper acquisition, interpretation, and longitudinal comparison.**

Essential Components for Liver MRI Iron Load Orders

Primary Method Specification

• Order R2-based relaxometry as the first-line method for liver iron concentration (LIC) quantification*, as this is the gold standard with high-level evidence 1
• Specify field strength: Use 1.5T for suspected severe iron overload (reliable up to ~40 mg/g LIC) or 3T for mild-moderate overload (reliable up to ~26 mg/g LIC) 1
• Document the indication clearly: "Assessment of transfusional iron overload in patient with [sickle cell disease/thalassemia/chronic transfusion therapy]" 2

Technical Parameters to Include

• Request short echo times (<1 msec), short echo spacing (<1 msec), 6-12 echo times 1
• Mandate fat correction and noise correction to avoid significant bias in measurements 1
• Specify that the same method must be used for all future studies to allow accurate longitudinal comparison 2

Clinical Context Documentation

• State current serum ferritin level and trend 2
• Note if patient is receiving iron chelation therapy (MRI helpful for titrating therapy regardless of ferritin) 2
• Document transfusion history and frequency 2

Essential Components for Cardiac MRI T2* Orders

When to Order Cardiac T2*

• Do NOT order routine cardiac T2 screening for all chronically transfused patients* 2
• Order cardiac T2 MRI specifically for patients with*:
  • High iron burden (LIC >15 mg/g dry weight) for ≥2 years 2
  • Evidence of end-organ damage from transfusional iron overload 2
  • Evidence of cardiac dysfunction on echocardiography 2
  • Idiopathic cardiomyopathy (to rule out iron overload as treatable cause) 2

Technical Specifications

• Request validated T2 method with mid-ventricular septal measurement* (best marker of global myocardial iron content) 2
• Specify same method must be used longitudinally for accurate comparison 2
• Include request for left ventricular ejection fraction, volumes, and mass assessment 2

Risk Stratification Documentation

• Note that cardiac T2 >20 ms = low risk (green zone)* for heart failure 2
• T2 10-20 ms = intermediate risk (yellow zone)* requiring closer monitoring 2
• T2 <10 ms = high risk (red zone)* requiring immediate intensification of chelation 2

Critical Annotation Elements for All Iron Overload MRI Orders

Mandatory Clinical Information

• Primary diagnosis: Specify exact genotype for sickle cell disease (SS, Sβ0, SC, etc.) or type of thalassemia 2
• Transfusion regimen: Simple transfusion vs. red cell exchange, frequency, duration of chronic transfusion 2
• Current chelation therapy: Agent, dose, compliance history 2
• Recent ferritin levels: Include trend over past 6-12 months 2

Reporting Requirements to Request

• Ask radiologist to specify the exact MRI method used with literature citation describing the calibration 1
• Request quantitative LIC values in both mg/g dry weight AND μmol/g 1
• For cardiac studies, request specific T2 value in milliseconds with risk zone classification* 2

Common Pitfalls to Avoid

Field Strength Errors

• Never order 3T MRI for suspected severe iron overload (>26 mg/g), as it will fail to quantify accurately due to dynamic range limitations 1
• Recognize that ferritin >3000 ng/mL typically indicates severe liver iron overload requiring 1.5T imaging 2

Method Consistency Failures

• Switching between R2, T2, and R2 methods invalidates longitudinal comparison** 2, 1
• Document the method used in previous studies and request the same technique 2

Inappropriate Cardiac Screening

• Avoid routine cardiac T2 in patients with well-controlled iron burden* (ferritin <1500 ng/mL, LIC <7 mg/g) 2
• Cardiac iron loading is uncommon in sickle cell disease compared to thalassemia, even with similar liver iron concentrations 2

Ferritin Misinterpretation

• Never rely on single ferritin measurement alone - inflammation, infection, and vitamin C deficiency cause misleading elevations 2, 3
• Ferritin correlates poorly with cardiac iron - patients can have cardiac siderosis with normal ferritin 2
• In sickle cell disease specifically, inflammation frequently elevates ferritin independent of iron burden 2

Sample Order Annotations

For Liver Iron Assessment

"MRI liver iron quantification using R2 relaxometry at 1.5T* for patient with sickle cell disease (SS genotype) on chronic monthly simple transfusion therapy for 5 years. Current ferritin 2800 ng/mL (trend: 2200→2500→2800 over past year). On deferasirox 30 mg/kg/day. Request fat-corrected, noise-corrected acquisition with 6-12 echoes. Report LIC in mg/g dw and μmol/g. Previous study 18 months ago used R2* method - please use same technique for comparison." 2, 1

For Cardiac Iron Assessment

"Cardiac MRI with T2 assessment* for patient with beta-thalassemia major with high iron burden (liver MRI 6 months ago showed LIC 18 mg/g dw, persistently elevated >15 mg/g for 3 years). Recent echocardiogram shows borderline decreased LVEF 52%. Request validated T2* method with mid-ventricular septal measurement, plus LV volumes, mass, and ejection fraction. Report T2* value in milliseconds with risk stratification (green/yellow/red zone)." 2