1. 1. Imaging of Bone MarrowImaging of Bone Marrow Jim Wu, MDJim Wu, MD Beth Israel Deaconess MedicalBeth Israel Deaconess Medical Center (BIDMC)Center (BIDMC) Harvard Medical SchoolHarvard Medical School
2. 2. DisclosuresDisclosures Kaneka Corp - research funding support Boehringer Ingelheim - research funding support PharmaMar - imaging consultant
3. 3. Learning ObjectivesLearning Objectives To learn the 2 types of bone marrow andTo learn the 2 types of bone marrow and normal conversion patternnormal conversion pattern To be able to distinguish normal fromTo be able to distinguish normal from abnormal bone marrow on MRIabnormal bone marrow on MRI Learn the MRI imaging appearance ofLearn the MRI imaging appearance of various bone marrow disordersvarious bone marrow disorders
4. 4. Bone Marrow TypesBone Marrow Types Red (hematopoietic)Red (hematopoietic) Present at birthPresent at birth 40% fatty40% fatty 40-50% hematopoietic cells40-50% hematopoietic cells Erythrocytes, megakaryocytes,Erythrocytes, megakaryocytes, granulocytesgranulocytes 10% structural elements10% structural elements Increased in marrowIncreased in marrow proliferative disordersproliferative disorders Islands of red marrow canIslands of red marrow can remain in long bonesremain in long bones Yellow (Fatty)Yellow (Fatty) Increases with ageIncreases with age 80% fatty80% fatty 10% hematopoietic cells10% hematopoietic cells Erythrocytes, megakaryocytes,Erythrocytes, megakaryocytes, granulocytesgranulocytes 10% structural elements10% structural elements Increased with marrowIncreased with marrow depletion processesdepletion processes (radiation)(radiation)
5. 5. Bone Marrow TypesBone Marrow Types Red (hematopoietic)Red (hematopoietic) Yellow (Fatty)Yellow (Fatty)
6. 6. Fatty Conversion of MarrowFatty Conversion of Marrow Converts fromConverts from RedRed (hematopoietic) to(hematopoietic) to YellowYellow (fatty)(fatty) Starts at hands and feet and worksStarts at hands and feet and works centrallycentrally Distal first, then proximalDistal first, then proximal Long bonesLong bones Epiphysis and diaphysis firstEpiphysis and diaphysis first Distal metaphysisDistal metaphysis Proximal metaphysisProximal metaphysis Complete by age 24-26Complete by age 24-26
7. 7. Fatty Conversion of MarrowFatty Conversion of Marrow Moore et al. Radiology 1990; 175:219-223
8. 8. Normal Marrow ConversionNormal Marrow Conversion 2 years 14 years 42 years T1 T1 T1 Courtesy of Dr. Mary Hochman, Boston
9. 9. MarrowMarrow ReRe -- conversionconversion Response to demandResponse to demand for hematopoiesisfor hematopoiesis Mature fatty marrowMature fatty marrow replaced byreplaced by hematopoietic marrowhematopoietic marrow Orderly sequenceOrderly sequence Reverse pattern ofReverse pattern of marrow conversionmarrow conversion
10. 10. Marrow ReconversionMarrow Reconversion Obese femalesObese females SmokersSmokers Hemolytic AnemiaHemolytic Anemia High altitudeHigh altitude AthletesAthletes Marrow-stimulatingMarrow-stimulating medications (e.g. GCSF),medications (e.g. GCSF), erythropoietin (EPOerythropoietin (EPO)) Replacement/destructionReplacement/destruction of normal marrowof normal marrow GCSF Therapy
11. 11. MRI Appearance of Red andMRI Appearance of Red and Yellow MarrowYellow Marrow Red (hematopoietic)Red (hematopoietic) Slightly hyperintense toSlightly hyperintense to muscle on T1muscle on T1 Hyperintense to fat on T2Hyperintense to fat on T2 Does not extend past theDoes not extend past the physisphysis Signal drop out on opposeSignal drop out on oppose phase T1 imagingphase T1 imaging Yellow (Fatty)Yellow (Fatty) Hyperintense to muscle onHyperintense to muscle on T1T1 Hypointense to muscle onHypointense to muscle on STIRSTIR No signal drop out onNo signal drop out on oppose phase T1 imagingoppose phase T1 imaging
12. 12. Hypointense Low Signal T1 STIR Hyperintense High Signal Normal Marrow - Yellow (Fatty)Normal Marrow - Yellow (Fatty)
13. 13. Normal Marrow Normal Marrow Hematopoietic (Red)Hematopoietic (Red) Iso- or Slightly Hyperintense to Muscle Hyperintense to Fat T1 STIR
14. 14. Likely benign Likely pathologic ????? Compare lesion to skeletal muscle on T1-weighted images Distinguishing Red Marrow Versus Tumor 1. Hyperintense 2. Hypointense 3. Isointense
15. 15. T1 T2 fat sat Normal Red MarrowNormal Red Marrow
16. 16. Abnormal Marrow - Plasmacytoma T1 T2 fat sat Key Point: Marrow should not be hypointense to normal skeletal muscle on T1
17. 17. T1 Opposed-Phase ImagesT1 Opposed-Phase Images In-phase Out-of-phaseIn-phase Out-of-phase
18. 18. Opposed-Phase MRIOpposed-Phase MRI Fat and water protons precess at slightly different frequencies At 1.5 Tesla: Water Fat Frequency (PPM) -3.5 PPM Opposed-phase: TE of ~2.3 ms In-phase: TE of ~4.6 ms
19. 19. Water Fat Water Fat In-phase Out-of-phase Opposed-Phase MRI
20. 20. In-phaseIn-phase Is this normal?? Out-of-phaseOut-of-phase No drop out, so does not contains fatMarrow darker than skeletal muscle B Cell Lymphoma
21. 21. Is this normal??Is this normal?? In-phaseIn-phase Out-of-phaseOut-of-phase
22. 22. Red Marrow Stops at physisRed Marrow Stops at physis T1T2 fat sat
23. 23. B Cell LymphomaB Cell Lymphoma T1 STIR
24. 24. Normal VariationNormal Variation Red Marrow inRed Marrow in SubchondralSubchondral EpiphysisEpiphysis
25. 25. Spine: Compare Marrow toSpine: Compare Marrow to Normal DiscNormal Disc Abnormal Marrow Hypo-intense Normal Marrow Hyper-intense T1 T1 Red Marrow Marrow Infiltration
26. 26. Additional MRI TechniquesAdditional MRI Techniques Diffusion weighted imaging (DWI)Diffusion weighted imaging (DWI) Malignancies have restricted diffusion (bright on ADCMalignancies have restricted diffusion (bright on ADC images)images) Helpful in distinguishing benign from malignantHelpful in distinguishing benign from malignant vertebral body compression fracturevertebral body compression fracture Dynamic contrast enhancement (DCE)Dynamic contrast enhancement (DCE) Better than static gad pre and post imagesBetter than static gad pre and post images Rates of enhancement can distinguish benign fromRates of enhancement can distinguish benign from malignant disorders depends on age and fat contentmalignant disorders depends on age and fat content MR spectroscopy (MRS)MR spectroscopy (MRS) Choline to lipid ratio may help distinguish benign fromCholine to lipid ratio may help distinguish benign from malignant bone marrow disordersmalignant bone marrow disorders
27. 27. Classification of Marrow DisordersClassification of Marrow Disorders Marrow proliferative disordersMarrow proliferative disorders Marrow replacement disordersMarrow replacement disorders Marrow depletionMarrow depletion Marrow edemaMarrow edema
28. 28. Marrow Proliferative DisordersMarrow Proliferative Disorders Overproduction of bone marrow elementsOverproduction of bone marrow elements Diffuse low signal on T1, variable on T2Diffuse low signal on T1, variable on T2 DiseasesDiseases myelofibrosismyelofibrosis polycythemia verapolycythemia vera myelodysplastic syndromemyelodysplastic syndrome leukemialeukemia multiple myelomamultiple myeloma amyloidosisamyloidosis
29. 29. Marrow Proliferative DisordersMarrow Proliferative Disorders T1T1 STIRSTIR
30. 30. Marrow Proliferative DisordersMarrow Proliferative Disorders T1T1 STIRSTIR Acute Myeloid Leukemia
31. 31. Marrow Proliferative DisordersMarrow Proliferative Disorders Different from disorders that lead to reconversionDifferent from disorders that lead to reconversion to red marrowto red marrow AnemiasAnemias SmokingSmoking HypoxiaHypoxia Chronic heart diseaseChronic heart disease Endurance athletesEndurance athletes G-CSF or erythropoietin (EPO)G-CSF or erythropoietin (EPO) Biopsy of reconversion disorders will yield normalBiopsy of reconversion disorders will yield normal red marrow whereas marrow proliferativered marrow whereas marrow proliferative disorders will be abnormaldisorders will be abnormal
32. 32. Marrow Replacement DisordersMarrow Replacement Disorders Infiltration of cells thatInfiltration of cells that do not belongdo not belong inin bone marrowbone marrow Typically focal or multifocal, NOT diffuseTypically focal or multifocal, NOT diffuse DiseasesDiseases METASTASESMETASTASES bone tumorsbone tumors osteomyelitisosteomyelitis lymphomalymphoma GauchersGauchers
33. 33. Marrow Replacement DisordersMarrow Replacement Disorders Breast CA metastases Osteomyelitis
34. 34. Which side is abnormal ??Which side is abnormal ?? B Cell Lymphoma T1
35. 35. Marrow DepletionMarrow Depletion Ablation or failure of redAblation or failure of red marrow elementsmarrow elements Looks like Fat!Looks like Fat! T1: like fatT1: like fat T2: like fatT2: like fat Distribution: diffuse orDistribution: diffuse or regionalregional Diseases:Diseases: Aplastic anemiaAplastic anemia Radiation therapyRadiation therapy ChemotherapyChemotherapy Post Radiation
36. 36. Marrow EdemaMarrow Edema Generic term for high signal on fluid sensitiveGeneric term for high signal on fluid sensitive sequencessequences Bone marrow edema due to hyperemia or ischemiaBone marrow edema due to hyperemia or ischemia T1: hypointenseT1: hypointense T2: high signal (marrow edema pattern)T2: high signal (marrow edema pattern) Distribution: focal, often at epiphysisDistribution: focal, often at epiphysis DiseasesDiseases trauma acute, chronic (osteoarthritis)trauma acute, chronic (osteoarthritis) infectioninfection osteonecrosisosteonecrosis transient edema, regional migratory edematransient edema, regional migratory edema inflammatory arthritisinflammatory arthritis
37. 37. Marrow EdemaMarrow Edema T1 STIR Transient Osteoporosis
38. 38. Marrow EdemaMarrow Edema T1 STIR Lunate Osteonecrosis Kienbocks Disease
39. 39. Distribution Diffuse (Proliferative, Infiltrative) Focal Multifocal
40. 40. Distribution - Diffuse Often symmetricOften symmetric Marrow reconversionMarrow reconversion Marrow proliferativeMarrow proliferative diseasesdiseases Multiple myelomaMultiple myeloma LeukemiaLeukemia Polycythemia veraPolycythemia vera MyelofibrosisMyelofibrosis Polycythemia Vera
41. 41. Distribution - Focal TumorTumor TraumaTrauma OsteonecrosisOsteonecrosis Transient edemaTransient edema InfectionInfection InflammationInflammation DegenerativeDegenerative RadiationRadiation Islands of red marrowIslands of red marrow T1 STIR Staph Discitis/Osteomyelitis
42. 42. Distribution - Multifocal MetastasesMetastases MyelomaMyeloma Multiple focalsMultiple focals Neuroblastoma Metastases
43. 43. SummarySummary Two types of bone marrow and predictableTwo types of bone marrow and predictable conversion patternconversion pattern [1] Red (hematopoietic) & [2] yellow (marrow)[1] Red (hematopoietic) & [2] yellow (marrow) Fatty conversion - Appendicular to AxialFatty conversion - Appendicular to Axial Epiphysis diaphysis distal metaphysisEpiphysis diaphysis distal metaphysis MRI appearance of normal and abnormal boneMRI appearance of normal and abnormal bone marrowmarrow Hyperintense on T1 when compared to muscle and discHyperintense on T1 when compared to muscle and disc Stops at physis or physeal scarStops at physis or physeal scar In and out of phase imaging red marrow drops outIn and out of phase imaging red marrow drops out
44. 44. SummarySummary Diseases with bone marrow abnormalities Marrow proliferative disorders myelofibrosis, polycythemia vera, leukemia, multiple myeloma Marrow replacement disorders metastases, bone tumors, osteomyelitis, lymphoma Marrow depletion aplastic anemia, radiation therapy, chemotherapy Marrow edema trauma , osteonecrosis, regional migratory edema, inflammatory arthritis
45. 45.