Diffusion-weighted MR imaging for characterizing musculoskeletal lesions

Abstract

Diffusion-weighted (DW) imaging is a functional magnetic resonance (MR) imaging technique that can readily be incorporated into a routine non-contrast material-enhanced MR imaging protocol with little additional scanning time. DW imaging is based on changes in the Brownian motion of water molecules caused by tissue microstructure. The apparent diffusion coefficient (ADC) is a quantitative measure of Brownian movement: Low ADC values typically reflect highly cellular microenvironments in which diffusion is restricted by the presence of cell membranes, whereas acellular regions allow free diffusion and result in elevated ADC values. Thus, with ADC mapping, one may derive useful quantitative information regarding the cellularity of a musculoskeletal lesion using a nonenhanced technique. The role of localized DW imaging in differentiating malignant from benign osseous and soft-tissue lesions is still evolving; when carefully applied, however, this modality has proved helpful in a subset of tumor types, such as nonmyxoid soft-tissue tumors. Studies of the use of DW imaging in assessing the treatment response of both osseous and soft-tissue tumors have shown that higher ADC values correlate with better response to cytotoxic therapy. Successful application of DW imaging in the evaluation of musculoskeletal lesions requires familiarity with potential diagnostic pitfalls that stem from technical artifacts and confounding factors unrelated to lesion cellularity. Further investigation is needed to evaluate the impact of DW imaging-ADC mapping on management and outcome in patients with musculoskeletal lesions.

Figure 1

Graph illustrates how the ADC value is calculated by plotting the natural logarithm of the signal intensities in the ROI on the DW images obtained with different b values and fitting a linear regression line (assuming a monoexponential fit). The ADC value is the negative of the slope of that line. In this case (that of a 24-year-old man), a benign neurofibroma exhibits a higher ADC value (mean, 2.3 × 10⁻³ mm²/sec) than does a malignant peripheral nerve sheath tumor in the pelvis (mean, 1.2 × 10⁻³ mm²/sec), reflecting the fact that the ADC value is generally higher for benign than for malignant disease.

Figure 2

ADC map of the pelvis (same patient as in Fig 1). Various ROI techniques have been used by different investigators, since there is no consensus in the literature as to how the ADC value for lesions should be measured. Here, a small ROI (circle) has been positioned in the malignant peripheral nerve sheath tumor, within an area that was visually judged to be the most hypointense and therefore suspected of having the highest lesion cellularity, yielding a minimum ADC of 0.61 × 10⁻³ mm²/sec and a mean ADC of 0.93 × 10⁻³ mm²/sec. Alternatively, a larger ROI (oval) encompassing most of the malignant peripheral nerve sheath tumor yielded a minimum ADC of 0.41 × 10⁻³ mm²/sec and a mean ADC of 1.2 × 10⁻³ mm²/sec. The lower minimum but higher mean ADC for the larger ROI highlight the potential for technical factors to skew results and complicate the interpretation of results achieved with various methodologies.

Figure 3a

Right hip ganglion in a 61-year-old man. (a) Sagittal short inversion time inversion-recovery SPACE (sampling perfection with application-optimized contrast using different flip-angle evolutions) image (TR/TE = 2290/171, flip angle = 120°) shows a T2-hyperintense mass with heterogeneously hypointense internal signal intensity anterior to the right hip. (b) Axial ADC map reveals a region of elevated ADC values (mean, 2.6 × 10⁻³ mm²/sec; minimum, 1.8 × 10⁻³ mm²/sec) in the area corresponding to the mass (arrow). (c) Postcontrast volume-interpolated breath-hold examination image (TR/TE = 6.35/1.48) helps confirm that the nonenhancing mass is a periarticular ganglion.

Figure 3b

Right hip ganglion in a 61-year-old man. (a) Sagittal short inversion time inversion-recovery SPACE (sampling perfection with application-optimized contrast using different flip-angle evolutions) image (TR/TE = 2290/171, flip angle = 120°) shows a T2-hyperintense mass with heterogeneously hypointense internal signal intensity anterior to the right hip. (b) Axial ADC map reveals a region of elevated ADC values (mean, 2.6 × 10⁻³ mm²/sec; minimum, 1.8 × 10⁻³ mm²/sec) in the area corresponding to the mass (arrow). (c) Postcontrast volume-interpolated breath-hold examination image (TR/TE = 6.35/1.48) helps confirm that the nonenhancing mass is a periarticular ganglion.

Figure 3c

Right hip ganglion in a 61-year-old man. (a) Sagittal short inversion time inversion-recovery SPACE (sampling perfection with application-optimized contrast using different flip-angle evolutions) image (TR/TE = 2290/171, flip angle = 120°) shows a T2-hyperintense mass with heterogeneously hypointense internal signal intensity anterior to the right hip. (b) Axial ADC map reveals a region of elevated ADC values (mean, 2.6 × 10⁻³ mm²/sec; minimum, 1.8 × 10⁻³ mm²/sec) in the area corresponding to the mass (arrow). (c) Postcontrast volume-interpolated breath-hold examination image (TR/TE = 6.35/1.48) helps confirm that the nonenhancing mass is a periarticular ganglion.

Figure 4a

Desmoid tumor (initially thought to represent a sarcoma) in a 25-year-old man. (a, b) Axial T2-weighted MR image (TR/TE = 3600/73) (a) and contrast-enhanced fat-suppressed T1-weighted volume-interpolated breath-hold examination image (TR/TE = 3.54/1.24) (b) show a large, mildly heterogeneous, avidly enhancing mass in the anterior abdominal wall (arrowheads in b). (c) Axial ADC map shows intermediate signal intensity in the mass (arrowheads), with minimum and mean ADC values of 1.1 × 10⁻³ mm²/sec and 1.8 × 10⁻³ mm²/sec, respectively, higher than expected for a nonmyxoid sarcoma. Biopsy and surgical resection revealed the mass to be fibromatosis (desmoid tumor). Ghosting artifact (arrows) can be seen with motion during DW imaging, although here, assessment of most of the mass is not affected.

Figure 4b

Desmoid tumor (initially thought to represent a sarcoma) in a 25-year-old man. (a, b) Axial T2-weighted MR image (TR/TE = 3600/73) (a) and contrast-enhanced fat-suppressed T1-weighted volume-interpolated breath-hold examination image (TR/TE = 3.54/1.24) (b) show a large, mildly heterogeneous, avidly enhancing mass in the anterior abdominal wall (arrowheads in b). (c) Axial ADC map shows intermediate signal intensity in the mass (arrowheads), with minimum and mean ADC values of 1.1 × 10⁻³ mm²/sec and 1.8 × 10⁻³ mm²/sec, respectively, higher than expected for a nonmyxoid sarcoma. Biopsy and surgical resection revealed the mass to be fibromatosis (desmoid tumor). Ghosting artifact (arrows) can be seen with motion during DW imaging, although here, assessment of most of the mass is not affected.

Figure 4c

Desmoid tumor (initially thought to represent a sarcoma) in a 25-year-old man. (a, b) Axial T2-weighted MR image (TR/TE = 3600/73) (a) and contrast-enhanced fat-suppressed T1-weighted volume-interpolated breath-hold examination image (TR/TE = 3.54/1.24) (b) show a large, mildly heterogeneous, avidly enhancing mass in the anterior abdominal wall (arrowheads in b). (c) Axial ADC map shows intermediate signal intensity in the mass (arrowheads), with minimum and mean ADC values of 1.1 × 10⁻³ mm²/sec and 1.8 × 10⁻³ mm²/sec, respectively, higher than expected for a nonmyxoid sarcoma. Biopsy and surgical resection revealed the mass to be fibromatosis (desmoid tumor). Ghosting artifact (arrows) can be seen with motion during DW imaging, although here, assessment of most of the mass is not affected.

Figure 5a

Sciatic nerve schwannoma in a 79-year-old woman. (a) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 4060/71) shows a round, hyperintense mass associated with the sciatic nerve and having a “target sign” appearance. (b) Corresponding ADC map shows the target sign appearance of the mass (arrow), created by a central area with greater cellularity (lower ADC values and hence lower signal intensity) than the lesion periphery. The tumor had a mean ADC of 1.8 × 10⁻³ mm²/sec and a minimum ADC of 1.5 × 10⁻³ mm²/sec.

Figure 5b

Sciatic nerve schwannoma in a 79-year-old woman. (a) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 4060/71) shows a round, hyperintense mass associated with the sciatic nerve and having a “target sign” appearance. (b) Corresponding ADC map shows the target sign appearance of the mass (arrow), created by a central area with greater cellularity (lower ADC values and hence lower signal intensity) than the lesion periphery. The tumor had a mean ADC of 1.8 × 10⁻³ mm²/sec and a minimum ADC of 1.5 × 10⁻³ mm²/sec.

Figure 6a

High-grade sarcoma in a 56-year-old woman. (a) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 3300/71) shows a large, partially cystic mass in the left thigh. (b) Corresponding axial ADC map shows high signal intensity in the areas of necrosis and low signal intensity in the medial peripheral cellular portions of the mass (overall minimum and average ADC values of 0.3 × 10⁻³ mm²/sec and 1.9 × 10⁻³ mm²/sec, respectively). Unlike the ADC map in Figure 4 (periarticular cyst), which showed no low-signal-intensity cellular region in the mass, this ADC map shows a sarcoma with a highly cellular peripheral component (arrows) and a necrotic center (*).

Figure 6b

High-grade sarcoma in a 56-year-old woman. (a) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 3300/71) shows a large, partially cystic mass in the left thigh. (b) Corresponding axial ADC map shows high signal intensity in the areas of necrosis and low signal intensity in the medial peripheral cellular portions of the mass (overall minimum and average ADC values of 0.3 × 10⁻³ mm²/sec and 1.9 × 10⁻³ mm²/sec, respectively). Unlike the ADC map in Figure 4 (periarticular cyst), which showed no low-signal-intensity cellular region in the mass, this ADC map shows a sarcoma with a highly cellular peripheral component (arrows) and a necrotic center (*).

Figure 7a

Trauma-related hematoma in a 33-year-old man. (a) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 4060/71) shows a well-circumscribed, heterogeneous, T2-hyperintense mass in the posteromedial soft tissues of the calf. Foci of low signal intensity along the lateral and posterior margins of the mass represent blood products. (b) Corresponding ADC map reveals low average and minimum ADC values in the lesion (0.52 × 10⁻³ mm²/sec and 0.16 × 10⁻³ mm²/sec, respectively) (arrows), findings that falsely suggest a solid neoplasm. (c) Postcontrast image reveals no internal enhancement within the mass, with a nonenhancing clot in the dependent portion. The mass was clinically confirmed to be a hematoma.

Figure 7b

Trauma-related hematoma in a 33-year-old man. (a) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 4060/71) shows a well-circumscribed, heterogeneous, T2-hyperintense mass in the posteromedial soft tissues of the calf. Foci of low signal intensity along the lateral and posterior margins of the mass represent blood products. (b) Corresponding ADC map reveals low average and minimum ADC values in the lesion (0.52 × 10⁻³ mm²/sec and 0.16 × 10⁻³ mm²/sec, respectively) (arrows), findings that falsely suggest a solid neoplasm. (c) Postcontrast image reveals no internal enhancement within the mass, with a nonenhancing clot in the dependent portion. The mass was clinically confirmed to be a hematoma.

Figure 7c

Trauma-related hematoma in a 33-year-old man. (a) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 4060/71) shows a well-circumscribed, heterogeneous, T2-hyperintense mass in the posteromedial soft tissues of the calf. Foci of low signal intensity along the lateral and posterior margins of the mass represent blood products. (b) Corresponding ADC map reveals low average and minimum ADC values in the lesion (0.52 × 10⁻³ mm²/sec and 0.16 × 10⁻³ mm²/sec, respectively) (arrows), findings that falsely suggest a solid neoplasm. (c) Postcontrast image reveals no internal enhancement within the mass, with a nonenhancing clot in the dependent portion. The mass was clinically confirmed to be a hematoma.

Figure 8a

Abscess in a 22-year-old woman. (a) Axial fat-suppressed T2-weighted MR image (TR/TE = 6130/54) shows a hyperintense mass with perilesional edema in the posterior compartment of the right thigh. Because the patient was pregnant, she did not receive intravenous contrast material for characterization of the mass. (b) Corresponding axial ADC map shows low signal intensity in the mass (arrows), with minimum and average ADC values of 0.3 × 10⁻³ mm²/sec and 0.6 × 10⁻³ mm²/sec, respectively, findings that are suspicious for malignancy. However, purulent discharge at needle biopsy and subsequent culture of Staphylococcus aureus confirmed the final diagnosis of an abscess.

Figure 8b

Abscess in a 22-year-old woman. (a) Axial fat-suppressed T2-weighted MR image (TR/TE = 6130/54) shows a hyperintense mass with perilesional edema in the posterior compartment of the right thigh. Because the patient was pregnant, she did not receive intravenous contrast material for characterization of the mass. (b) Corresponding axial ADC map shows low signal intensity in the mass (arrows), with minimum and average ADC values of 0.3 × 10⁻³ mm²/sec and 0.6 × 10⁻³ mm²/sec, respectively, findings that are suspicious for malignancy. However, purulent discharge at needle biopsy and subsequent culture of Staphylococcus aureus confirmed the final diagnosis of an abscess.

Figure 9a

Stress fracture in a 15-year-old girl with lower leg pain. The patient was referred from an outside institution for what was thought (based on marrow signal abnormalities) to be Ewing sarcoma. (a) Coronal T1-weighted MR image (TR/TE 730/9.2) shows an area of low signal intensity in the tibial diaphysis. (b) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 4060/71) shows intramedullary and periosteal edema. (c) ADC map shows a mean ADC of 1.6 × 10⁻³ mm²/sec and a minimum ADC of 1.4 × 10⁻³ mm²/sec in the region of bone marrow edema (arrow), findings that are consistent with a non–marrow-replacing stress fracture. The resolution of symptoms at clinical follow-up confirmed the diagnosis.

Figure 9b

Stress fracture in a 15-year-old girl with lower leg pain. The patient was referred from an outside institution for what was thought (based on marrow signal abnormalities) to be Ewing sarcoma. (a) Coronal T1-weighted MR image (TR/TE 730/9.2) shows an area of low signal intensity in the tibial diaphysis. (b) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 4060/71) shows intramedullary and periosteal edema. (c) ADC map shows a mean ADC of 1.6 × 10⁻³ mm²/sec and a minimum ADC of 1.4 × 10⁻³ mm²/sec in the region of bone marrow edema (arrow), findings that are consistent with a non–marrow-replacing stress fracture. The resolution of symptoms at clinical follow-up confirmed the diagnosis.

Figure 9c

Stress fracture in a 15-year-old girl with lower leg pain. The patient was referred from an outside institution for what was thought (based on marrow signal abnormalities) to be Ewing sarcoma. (a) Coronal T1-weighted MR image (TR/TE 730/9.2) shows an area of low signal intensity in the tibial diaphysis. (b) Axial fat-suppressed fast spin-echo T2-weighted MR image (TR/TE = 4060/71) shows intramedullary and periosteal edema. (c) ADC map shows a mean ADC of 1.6 × 10⁻³ mm²/sec and a minimum ADC of 1.4 × 10⁻³ mm²/sec in the region of bone marrow edema (arrow), findings that are consistent with a non–marrow-replacing stress fracture. The resolution of symptoms at clinical follow-up confirmed the diagnosis.

Figure 10a

Right pelvic osteosarcoma in a 14-year-old girl who had undergone chemotherapy. (a) Axial 3.0-T T1-weighted MR image (TR/TE = 576/9.4) shows a marrow-replacing tumor in the right acetabulum and an associated soft-tissue mass. Normal marrow is seen in the left acetabulum. (b) On an axial ADC map, the treated osteosarcoma demonstrates high signal intensity (minimum ADC, 1.7 × 10⁻³ mm²/sec; average ADC, 2.1 × 10⁻³ mm²/sec). In contrast, the normal marrow in the left acetabulum has a minimum ADC of 0.3 × 10⁻³ mm²/sec and an average ADC of 0.6 × 10⁻³ mm²/sec. Unlike in the soft tissues, the ADC values of tumors are greater than those of normal bone marrow, making DW imaging a useful technique for bone tumor detection.

Figure 10b

Right pelvic osteosarcoma in a 14-year-old girl who had undergone chemotherapy. (a) Axial 3.0-T T1-weighted MR image (TR/TE = 576/9.4) shows a marrow-replacing tumor in the right acetabulum and an associated soft-tissue mass. Normal marrow is seen in the left acetabulum. (b) On an axial ADC map, the treated osteosarcoma demonstrates high signal intensity (minimum ADC, 1.7 × 10⁻³ mm²/sec; average ADC, 2.1 × 10⁻³ mm²/sec). In contrast, the normal marrow in the left acetabulum has a minimum ADC of 0.3 × 10⁻³ mm²/sec and an average ADC of 0.6 × 10⁻³ mm²/sec. Unlike in the soft tissues, the ADC values of tumors are greater than those of normal bone marrow, making DW imaging a useful technique for bone tumor detection.

Figure 11a

Rhabdomyosarcoma in an 81-year-old woman. (a, b) Coronal 3.0-T short inversion time inversion-recovery (TR/TE = 3500/23) (a) and axial T2-weighted (TR/TE = 2330/64) (b) MR images obtained prior to chemotherapy show a mass with perilesional edema. (c) Corresponding axial ADC map (b = 50, 400, and 800 sec/mm²) shows an area of low signal intensity that corresponds to a cellular tumor (arrow), with minimum and average ADC values of 0.4 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3.0-T T2-weighted MR image obtained following chemotherapy shows a slight decrease in tumor size and a slight increase in signal heterogeneity. (e) Corresponding ADC map shows the tumor with increased signal intensity (arrow) and minimum and average ADC values of 1.1× 10⁻³ mm²/sec and 2.0 × 10⁻³ mm²/sec, respectively, findings that are consistent with good treatment response and the final histologic results (90% treatment-related sclerosis, 5% necrosis, and only 5% viable tumor).

Figure 11b

Rhabdomyosarcoma in an 81-year-old woman. (a, b) Coronal 3.0-T short inversion time inversion-recovery (TR/TE = 3500/23) (a) and axial T2-weighted (TR/TE = 2330/64) (b) MR images obtained prior to chemotherapy show a mass with perilesional edema. (c) Corresponding axial ADC map (b = 50, 400, and 800 sec/mm²) shows an area of low signal intensity that corresponds to a cellular tumor (arrow), with minimum and average ADC values of 0.4 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3.0-T T2-weighted MR image obtained following chemotherapy shows a slight decrease in tumor size and a slight increase in signal heterogeneity. (e) Corresponding ADC map shows the tumor with increased signal intensity (arrow) and minimum and average ADC values of 1.1× 10⁻³ mm²/sec and 2.0 × 10⁻³ mm²/sec, respectively, findings that are consistent with good treatment response and the final histologic results (90% treatment-related sclerosis, 5% necrosis, and only 5% viable tumor).

Figure 11c

Rhabdomyosarcoma in an 81-year-old woman. (a, b) Coronal 3.0-T short inversion time inversion-recovery (TR/TE = 3500/23) (a) and axial T2-weighted (TR/TE = 2330/64) (b) MR images obtained prior to chemotherapy show a mass with perilesional edema. (c) Corresponding axial ADC map (b = 50, 400, and 800 sec/mm²) shows an area of low signal intensity that corresponds to a cellular tumor (arrow), with minimum and average ADC values of 0.4 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3.0-T T2-weighted MR image obtained following chemotherapy shows a slight decrease in tumor size and a slight increase in signal heterogeneity. (e) Corresponding ADC map shows the tumor with increased signal intensity (arrow) and minimum and average ADC values of 1.1× 10⁻³ mm²/sec and 2.0 × 10⁻³ mm²/sec, respectively, findings that are consistent with good treatment response and the final histologic results (90% treatment-related sclerosis, 5% necrosis, and only 5% viable tumor).

Figure 11d

Rhabdomyosarcoma in an 81-year-old woman. (a, b) Coronal 3.0-T short inversion time inversion-recovery (TR/TE = 3500/23) (a) and axial T2-weighted (TR/TE = 2330/64) (b) MR images obtained prior to chemotherapy show a mass with perilesional edema. (c) Corresponding axial ADC map (b = 50, 400, and 800 sec/mm²) shows an area of low signal intensity that corresponds to a cellular tumor (arrow), with minimum and average ADC values of 0.4 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3.0-T T2-weighted MR image obtained following chemotherapy shows a slight decrease in tumor size and a slight increase in signal heterogeneity. (e) Corresponding ADC map shows the tumor with increased signal intensity (arrow) and minimum and average ADC values of 1.1× 10⁻³ mm²/sec and 2.0 × 10⁻³ mm²/sec, respectively, findings that are consistent with good treatment response and the final histologic results (90% treatment-related sclerosis, 5% necrosis, and only 5% viable tumor).

Figure 11e

Rhabdomyosarcoma in an 81-year-old woman. (a, b) Coronal 3.0-T short inversion time inversion-recovery (TR/TE = 3500/23) (a) and axial T2-weighted (TR/TE = 2330/64) (b) MR images obtained prior to chemotherapy show a mass with perilesional edema. (c) Corresponding axial ADC map (b = 50, 400, and 800 sec/mm²) shows an area of low signal intensity that corresponds to a cellular tumor (arrow), with minimum and average ADC values of 0.4 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3.0-T T2-weighted MR image obtained following chemotherapy shows a slight decrease in tumor size and a slight increase in signal heterogeneity. (e) Corresponding ADC map shows the tumor with increased signal intensity (arrow) and minimum and average ADC values of 1.1× 10⁻³ mm²/sec and 2.0 × 10⁻³ mm²/sec, respectively, findings that are consistent with good treatment response and the final histologic results (90% treatment-related sclerosis, 5% necrosis, and only 5% viable tumor).

Figure 12a

Primary bone lymphoma in a 23-year-old man. (a, b) Sagittal T1-weighted (735/9.5) (a) and axial T2-weighted (3600/71) (b) 3-T MR images before chemotherapy show a marrow-replacing tumor in the distal femur. Arrows in b = extraosseous soft-tissue mass medial and posterior to the tumor. (c) Corresponding axial ADC map shows diffuse low signal intensity in the tumor, with minimum and average ADC values of 0.3 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3-T T2-weighted MR image after chemotherapy shows decrease in size of the soft-tissue mass. (e) Corresponding ADC map shows interval increase in the signal intensity of the tumor, with minimum and average ADC values of 1.7 × 10⁻³ mm²/sec and 2.1 × 10⁻³ mm²/sec, respectively, findings consistent with excellent treatment response (confirmed at follow-up).

Figure 12b

Primary bone lymphoma in a 23-year-old man. (a, b) Sagittal T1-weighted (735/9.5) (a) and axial T2-weighted (3600/71) (b) 3-T MR images before chemotherapy show a marrow-replacing tumor in the distal femur. Arrows in b = extraosseous soft-tissue mass medial and posterior to the tumor. (c) Corresponding axial ADC map shows diffuse low signal intensity in the tumor, with minimum and average ADC values of 0.3 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3-T T2-weighted MR image after chemotherapy shows decrease in size of the soft-tissue mass. (e) Corresponding ADC map shows interval increase in the signal intensity of the tumor, with minimum and average ADC values of 1.7 × 10⁻³ mm²/sec and 2.1 × 10⁻³ mm²/sec, respectively, findings consistent with excellent treatment response (confirmed at follow-up).

Figure 12c

Primary bone lymphoma in a 23-year-old man. (a, b) Sagittal T1-weighted (735/9.5) (a) and axial T2-weighted (3600/71) (b) 3-T MR images before chemotherapy show a marrow-replacing tumor in the distal femur. Arrows in b = extraosseous soft-tissue mass medial and posterior to the tumor. (c) Corresponding axial ADC map shows diffuse low signal intensity in the tumor, with minimum and average ADC values of 0.3 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3-T T2-weighted MR image after chemotherapy shows decrease in size of the soft-tissue mass. (e) Corresponding ADC map shows interval increase in the signal intensity of the tumor, with minimum and average ADC values of 1.7 × 10⁻³ mm²/sec and 2.1 × 10⁻³ mm²/sec, respectively, findings consistent with excellent treatment response (confirmed at follow-up).

Figure 12d

Primary bone lymphoma in a 23-year-old man. (a, b) Sagittal T1-weighted (735/9.5) (a) and axial T2-weighted (3600/71) (b) 3-T MR images before chemotherapy show a marrow-replacing tumor in the distal femur. Arrows in b = extraosseous soft-tissue mass medial and posterior to the tumor. (c) Corresponding axial ADC map shows diffuse low signal intensity in the tumor, with minimum and average ADC values of 0.3 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3-T T2-weighted MR image after chemotherapy shows decrease in size of the soft-tissue mass. (e) Corresponding ADC map shows interval increase in the signal intensity of the tumor, with minimum and average ADC values of 1.7 × 10⁻³ mm²/sec and 2.1 × 10⁻³ mm²/sec, respectively, findings consistent with excellent treatment response (confirmed at follow-up).

Figure 12e

Primary bone lymphoma in a 23-year-old man. (a, b) Sagittal T1-weighted (735/9.5) (a) and axial T2-weighted (3600/71) (b) 3-T MR images before chemotherapy show a marrow-replacing tumor in the distal femur. Arrows in b = extraosseous soft-tissue mass medial and posterior to the tumor. (c) Corresponding axial ADC map shows diffuse low signal intensity in the tumor, with minimum and average ADC values of 0.3 × 10⁻³ mm²/sec and 1.1 × 10⁻³ mm²/sec, respectively. (d) Axial 3-T T2-weighted MR image after chemotherapy shows decrease in size of the soft-tissue mass. (e) Corresponding ADC map shows interval increase in the signal intensity of the tumor, with minimum and average ADC values of 1.7 × 10⁻³ mm²/sec and 2.1 × 10⁻³ mm²/sec, respectively, findings consistent with excellent treatment response (confirmed at follow-up).