Magnetic Resonance Imaging Findings of Grafted Cancellous Allografts after Removal of Bone Tumors

Seungcheol Kang, Ilkyu Han,

Sunghwan Hong, Hwan Seong Cho, Han-Soo Kim

Musculoskeletal Tumor Center, Seoul National University Cancer Hospital, Seoul, Korea

- CTOS 2014 -

Cancellous Allograft

• Allograft

: Donor site morbidity↓ / Quantity ↑

→ Commonly used in bone tumor surgery

• Cancellous allograft

: Fill defect after curettage of bone tumor

MRI in Bone Tumors

• Follow-up modality for surveillance of recurrence

• Curettage + Cancellous allograft

→ MRI DDx. cancellous allograft vs. recurred tumor

• No report on MRI findings of cancellous allograft

Purpose

To investigate the MRI features of

• Cancellous allograft & their change over time

• Cancellous allograft vs. Recurred tumors

Reviewed (n=53)

Curettage and cancellous allograft between 2002~2011

MRI for follow-up

Metallic device, BMP, or calcium component (n=17)

Lost to follow-up within 1 year after imaging (n=2)

Analyzed (n=34)

Excluded (n=19)

Patient Selection

• Age: 27 years (11-64)

• Sex: M (18) F (14)

• Tumor typeChondroblastoma (11), LG chonsa (10), ABC (3), GCT (2), FD (2), SBC (2), IO lipoma (1), PVNS (1)

• Site Femur (12), tibia (8), pelvis (5), humerus (4), foot (4)

• Tumor size: 6.7 ± 6.3 cm

Patient Characteristics

• 1.5- or 3.0-Tesla MRI scanners

• Sequences• T1WI: spin-echo T1-weighted • T2WI: fast spin-echo T2-weighted • Enhanced T1: gadolinium-enhanced spin-echo T1WI

• Review by 2 independent authors

Acquisition of MRIs

• 66 MRIs in 34 patients 1 MRI: 17 patients ≥ 2 MRIs: 17 patients

• Time from Surgery to MRI: 23 months (3-94)

• Time interval

Analysis of MRIs

Surgery 6mon 1yr 2yr 3yr

12 MRIs 17 MRIs 18 MRIs 11 MRIs 8 MRIs

• Typical MRI features of cancellous allograft

• Changes of cancellous allograft over time Typical MRI features Graft incorporation GD enhancement

• Tumor recurrence

Analysis Points

Results

Typical MRI Features• T1

Homogeneous intermediate SI ±Speckled hyperintensities

Typical MRI Features• T1

Homogeneous intermediate SI ± Speckled hyperintensities

• T2 High SI ± Speckled hypointensities

Typical MRI Features• T1

Homogeneous intermediate SI ± Speckled hyperintensities

• T2 High SI ± Speckled hypointensities

• Enhanced T1 Peripheral rim enhance ± Central heterogeneous enhance

Typical MRI Features• T1

Homogeneous intermediate SIs ± Speckled hyperintensities

• T2 High SIs ± Speckled hypointensities

• Enhanced T1 Peripheral rim enhance ± Central heterogeneous enhance

Present in

all cases (n=12)

Changes of Typical MRI Features

T1 100% 82% 67% 60% 0%

T2 100% 59% 33% 17% 0%

En-T1 100% 100% 87% 50% 0%

Surgery 6mon 1yr 2yr 3yr

Changes of Over Time

Graft Incorporation

Peripheral 0% 24% 50% 54% -

Complete 0% 0% 17% 46% 100%

Total 0% 24% 67% 100% 100%

Surgery 6mon 1yr 2yr 3yr

Changes of Over Time

Graft IncorporationPO 10mon PO 18mon

Changes of Over Time

GD Enhancement

100% 59% 33% 17% 0%

Surgery 6mon 1yr 2yr 3yr

Changes of Over Time

PO 5mon PO 34mon

GD EnhancementChanges of Over Time

Suspicious Recurrence on MRI (n=8)

No recurrence (n=3)

Recurrence on MRI

Recurrence (n=5)

vs. Recurrence

Suspicious Recurrence on MRI (n=8)

No recurrence (n=3)

Recurrence on MRI

Recurrence (n=5)

Same SI with primary tumor

vs. Recurrence

Recur Initial

Recurrence PO 9 mon

vs. Recurrence

Suspicious Recurrence on MRI (n=8)

MRIs < 1 year after surgery Chondrosarcomas

No recurrence (n=3)

Recurrence on MRI

Recurrence (n=5)

vs. Recurrence

No Recurrence PO 23 mon

Pre-op FU

vs. Recurrence

T1 T2 En-T1

PO

12mon

vs. Recurrence

T1 T2 En-T1

PO

12mon

PreOp

vs. Recurrence

T1 T2 En-T1

PO

12mon

PreOp

vs. Recurrence

T1 T2 En-T1

PO

12mon

PreOp

vs. Recurrence

T1 T2 En-T1

PO

12mon

PreOp

vs. Recurrence

T1 T2 En-T1

PO

12mon

PreOp

vs. Recurrence

Summary & Conclusion

• This study assessed the MRI features of cancellous allo-grafts & their change over time, and the differentiating fea-tures between cancellous allografts and recurred tumors.

Summary & Conclusion

• This study assessed the MRI features of cancellous allo-grafts & their change over time, and the differentiating fea-tures between cancellous allografts and recurred tumors.

• Cancellous allografts typically showed homogeneous inter-mediate or low SIs on T1, high SIs with speckled hypointen-sities on T2, and peripheral rim enhancements on enhanced T1.

Summary & Conclusion

• This study assessed the MRI features of cancellous allo-grafts & their change over time, and the differentiating fea-tures between cancellous allografts and recurred tumors.

• Cancellous allografts typically showed homogeneous inter-mediate or low Sis on T1, high SIs with speckled hypointen-sities on T2, and peripheral rim enhancements on enhanced T1.

• These typical features were maintained until 6 months and then gradually disappeared by 3 years.

Summary & Conclusion

• Graft incorporation occurred from periphery to center and were completed within 3 years.

Summary & Conclusion

• Graft incorporation occurred from periphery to center and were completed within 3 years.

• The single most differentiating feature of a recurred tumor was showing the similar pattern and SI of the primary tumor.

Summary & Conclusion

• Graft incorporation occurred from periphery to center and were completed within 3 years.

• The single most differentiating feature of a recurred tumor was showing the similar pattern and SI of the primary tumor.

• Careful interpretation is warranted when dealing with chon-droid tumors, especially for MRIs performed within 1 year of surgery.