Diffusion-weighted Imaging of Metastatic Brain Tumors: Comparison with Histologic Type and Tumor Cellularity

A 67-year-old man with a well differentiated adenocarcinoma from the lung.

A, T2-weighted fast spin-echo image shows a parietotemporal lesion (arrow) near the trigone of the left lateral ventricle. It is hypointense relative to the normal-appearing white matter. The CNR of the solid lesion was 12.

B, On contract-enhanced T1-weighted image, the lesion is enhanced (arrow).

C, On DWI, the lesion is hypointense relative to the normal-appearing white matter (arrow). It was graded as −2.

D, On ADC map, the nADC of the lesion was calculated as 1.95.

E, Photomicrograph of the specimen (hematoxylin-eosin stain; original magnification, 40×) shows a well-differentiated acinar structure. Tumor cellularity was calculated as 0.179.

A 41-year-old man with a poorly differentiated adenocarcinoma from the lung.

A, T2-weighted fast spin-echo image shows a left parietal subcortical lesion (arrow). It is slightly hyperintense relative to the normal-appearing white matter. The CNR of the solid lesion was 32.

B, On contract-enhanced T1-weighted image, the lesion is well enhanced (arrow).

C, On DWI, the lesion is slightly hyperintense relative to the normal-appearing cortical gray matter (arrow). It was graded as +1.

D, On ADC map, the nADC of the lesion was calculated as 1.45.

E, Photomicrograph of the specimen (hematoxylin-eosin stain; original magnification, 40×) shows higher cellularity than Fig 2E. Tumor cellularity was calculated as 0.334.

A 69-year-old man with small-cell carcinoma from the lung.

A, On T2-weighted fast spin-echo image, the solid portion of a right parietal mass lesion (arrow) is hyperintense relative to the normal-appearing white matter. The CNR of the enhancing lesion was 45.

B, On contract-enhanced T1-weighted image, the peripheral region of the lesion is enhanced (arrow).

C, On DWI, the lesion is hyperintense relative to the normal-appearing cortical gray matter (arrow). The lesion was graded as +2.

D, On ADC map, the solid lesion is slightly hyperintense. Its nADC was calculated as 0.57.

E, Photomicrograph of the specimen (hematoxylin-eosin stain; original magnification, 40×) shows high cellularity. The tumor cellularity was calculated as 0.72.

A 63-year-old man with large cell neuroendocrine carcinoma from the lung.

A, On T2-weighted fast spin-echo image, the solid portion of left occipital lesion (arrow) is hyperintense relative to the normal-appearing white matter. The CNR of the enhancing lesion was 56.

B, On contrast-enhanced T1-weighted image, the posterior part of the lesion is enhanced (arrow). There are multiple enhancing areas (arrowheads) in the left frontal lobe indicative of subacute infarction.

C, On DWI, the solid lesion is hyperintense relative to the normal-appearing cortical gray matter (arrow). The lesion was ranked as grade +2.

D, On ADC map, the solid lesion is hypointense; its nADC was calculated as 1.04.

E, Photomicrograph of the specimen (hematoxylin-eosin stain; original magnification, 40×) shows high cellularity. The tumor cellularity was calculated as 0.51.

Comparison of the nADC value and CNR on T2-weighted images of 26 metastatic brain tumors of different histologic types. Most well differentiated adenocarcinomas (Well diff. AC) are distributed at high nADC and low CNR. Of the 3 small-cell carcinomas (Small cell ca.), 2 exhibit nADC values below 1.0. The large-cell neuroendocrine carcinoma (LCNC) manifests low nADC value and high CNR. Poorly differentiated adenocarcinoma (Poorly diff. AC), papillotubular carcinoma (Papillotubular ca.), sarcoma, and malignant melanoma (Melanoma) also exhibit low nADC values. Large cell ca. indicates large cell carcinoma; SCC, squamous cell carcinoma; Mucoepidermoid ca.: mucoepidermoid carcinoma; Mod. diff. AC, moderately differentiated adenocarcinoma.

Comparison of the signal intensity of 13 histologically confirmed brain lesions on diffusion-weighted images. All 4 well differentiated adenocarcinomas (Well diff. AC) were graded as −2 or −1, and 2 poorly differentiated adenocarcinomas (Poorly diff. AC) as +1. One small-cell carcinoma (Small cell ca.) and 1 large-cell neuroendocrine carcinoma (LCNC) were both graded as +2. The other lesions were graded as 0 or +1. The signal intensity was graded on 5-point scale as described in Fig 1. Large cell ca., large cell carcinoma; SCC, squamous cell carcinoma; Papillotubular ca., papillotubular indicates carcinoma; Mucoepidermoid ca., mucoepidermoid carcinoma.

Comparison of the nADC value and CNR on T2-weighted images of 13 histologically confirmed brain lesions. Most well differentiated adenocarcinomas (Well diff. AC) are distributed at high nADC and low CNR. One small-cell carcinoma (Small cell ca.) and 1 large cell neuroendocrine carcinoma (LCNC) were distributed at low nADC and high CNR. Poorly diff. AC indicates poorly differentiated adenocarcinoma; Large cell ca., large cell carcinoma; SCC, squamous cell carcinoma; Mucoepidermoid ca., mucoepidermoid carcinoma; Papillotubular ca., papillotubular carcinoma.