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Dr/ ABD ALLAH NAZEER. MD.
Radiological application of diffusion
weighted images in abdomen and pelvis.
DWI in the abdomen and pelvis is a valuable adjunct to traditional
techniques and improves the sensitivity of MRI for lesion detection,
especially metastases. Furthermore, DWI may enhance the ability to
characterize lesions, particularly when gadolinium administration is
contraindicated or contrast-enhanced images are suboptimal. Even in
the presence of dynamic contrast-enhanced imaging, DWI may yield
supportive evidence and increase the confidence in a specific diagnosis.
DWI should always be used in conjunction with the information
provided by additional sequences. DWI and ADC maps provide an
opportunity for tissue characterization using a quantitative method,
thus offering a new opportunity for longitudinal assessment of tumors
undergoing therapy; however, further research is necessary to
determine the role of such quantitative analysis in clinical practice.
Given these merits and the ubiquitous availability of DWI on current
MRI systems, DWI may be implemented as a routine sequence in
standard abdominal MRI protocols and considered of the most value
when IV contrast agents cannot be administered.
With advances in hardware and coil systems, diffusion-weighted
(DW) MR imaging can now be applied to liver imaging with
improved image quality. DW MR imaging enables qualitative and
quantitative assessment of tissue diffusivity (apparent diffusion
coefficient) without the use of gadolinium chelates, which makes
it a highly attractive technique, particularly in patients with
severe renal dysfunction at risk for nephrogenic systemic fibrosis.
In this review, acquisition parameters, postprocessing, and
quantification methods applied to liver DW MR imaging will be
discussed. The current clinical uses of DW MR imaging (liver
lesion detection and characterization, compared and combined
with conventional sequences) and the emerging applications of
DW MR imaging (tumor treatment response and diagnosis of
liver fibrosis and cirrhosis) will be reviewed. Also, limitations,
mainly image quality and reproducibility of diffusion parameters,
and future directions of liver DW MR imaging will be discussed.
DWI may be used to diagnosis also with a significant
success for follow-up of patients with Inflammatory
appendiceal mass (IAM). As a monitoring imaging method,
DWI may also aid in determining of most appropriate
timing for interval appendectomy as well as may help in
diagnosing alternative diagnoses (e.g. malignancy and
inflammatory bowel disease) that can mimic IAM.
A combination of DWI and conventional MRI was the most
sensitive and the most accurate, with corresponding
sensitivity and accuracy of 0.92 and 0.92, respectively.
Using DWI alone the sensitivity and accuracy was found
to be 0.78 and 0.77, respectively. Using conventional MRI
alone, sensitivity of 0.81 and accuracy of 0.82 was found
for the consensus of the two observers.
An 11-year-old boy with a normal appendix. a: Axial TSE T2-weighted image showing the appendix. Arrow:
appendix. b, c: Diffusion-weighted MR image of the appendix with b value of 400 s/mm2 and 800 s/mm2
showing hypointensity of the appendix. Arrow: appendix. d: ADC image showing hyperintensity of the
appendix. ROI was placed on the appendix. ADC was 2.08 103 mm2 /s. Arrow: appendix
An 11-year-old girl with acute appendicitis and fluid collection. a: Axial TSE T2-weighted image
showing the appendix. Arrow: appendix, f: fluid. b, c: Diffusion-weighted MR image of the appendix
with b value of 400 s/mm2 and 800 s/mm2 showing marked hyperintensity. Arrow: appendix; f: fluid.
d: ADC image showing hypointensity of the appendix (marked restricted diffusion). ROI was placed
on the appendix. ADC was 1.12 103 mm2 /s. Arrow: appendix, f: fluid.
An 8-year-old boy with acute appendicitis. a: Axial TSE T2-weighted image showing the appendix
(arrow). b, c: Diffusion-weighted MR image of the appendix (arrow) with b value of 400 s/mm2 and
800 s/mm2 showing marked hyperintensity. d: ADC image showing hypointensity of the appendix
(marked restricted diffusion). ROI was placed on the appendix (arrow). ADC was 0.97 103 mm2 /s.
Pregnant women with acute appendicitis.
Apparent diffusion coefficient (ADC) map
corresponding to A and B also shows
appendix with excellent conspicuity and
confirms restricted diffusion in appendix.
High ADC values in periappendiceal fluid
indicate T2 shine-through from simple fluid.
A 34-year-old man with acute right
lower quadrant pain for a day had acute
appendicitis at surgery. A, Non-
enhanced computed tomography (NECT)
shows enlargement of the appendix
with some stranding of surrounding
fatty tissue (arrows). B, Diffusion
weighted imaging (DWI) clearly depicts
an enlarged hyperintense tubular
structure (arrows) and C, Apparent
diffusion coefficient (ADC) map shows
diffusion restriction (arrows).
A 18-year-old man with right
lower quadrant pain for the last
two days. Following surgery,
microscopy revealed lymphoid
hyperplasia without findings of
acute appendicitis. Non-
enhanced computed tomography
(NECT) (not shown here) shows
only slight enlargement of the
appendix with fine peri
appendiceal fatty tissue.
Combined imaging report was
positive for acute appendicitis. A,
Diffusion weighted imaging
(DWI) shows enlargement of the
appendix with hyperintense
signal (arrows) and B, Apparent
diffusion coefficient (ADC) map
shows restricted diffusion of the
A 37 -year-old female patient with right
lower quadrant pain for the last two days.
Surgery revealed acute appendicitis. A,
Non-enhanced computed tomography
(NECT) shows a slightly enlarged appendix
(8.6 mm) with fine surrounding fatty tissue
planes that was reported as normal by
NECT only review (arrows). B, Diffusion
weighted imaging (DWI) depicts a strong
hyperintense signal of the enlarged
appendix (arrows) with some peri
appendiceal fat blurring, and C, Apparent
diffusion coefficient (ADC) map reveals
diffusion restriction (arrows).
A 48-year-old male with acute
right lower quadrant (RLQ) pain
for 4 days. Clinical, laboratory and
imaging findings suggested IAM.
The patient underwent interval
appendectomy at the fourth week
(a) CT at presentation shows a
RLQ mass (IAM) bordered by
cecum laterally, ileum anteriorly
and gerota fascia posteriorly
(arrow). (b, c) DWI (b = 1000) and
ADC map at presentation show
restricted diffusion (arrow). (d, e)
Four weeks after initial
presentation, DWI (b = 1000) and
ADC map reveal total recovery at
the localization of previous IAM,
both qualitatively and
quantitatively. (f) Microscopy of
appendectomy specimen shows no
any inflammatory cells.
54-year-old male with right lower quadrant
(RLQ) pain for last 5 days. Clinical, laboratory
and imaging findings were suggestive of IAM at
presentation. Although there was relief of pain
and improvement of laboratory tests following
two weeks antibiotic therapy, on control DWI
there was not any change of the RLQ mass (not
shown in the figure). Colonoscopy performed at
second week of follow-up showed a cecal mass.
Surgery revealed cecal adenocarcinoma with
(a) CT at presentation shows a complex RLQ
inflammatory mass (arrows). (b, c) DWI (b = 500)
and ADC map at presentation show restricted
diffusion of the mass (arrows).
A 37-year-old female with right
lower quadrant (RLQ) pain for last
3 days. Clinical, laboratory and
imaging findings were suggestive
of IAM at presentation. At the
sixth moth of follow-up the
patient came over with RLQ pain
suggestive of relapse of
appendicitis. Imaging findings
were compatible with IAM.
(a, b) DWI and ADC map reveal a
RLQ mass with diffusion restriction
at the time of first presentation
(arrows). (c, d) Control DWI and
ADC map show complete
regression of IAM with antibiotic
therapy. (e, f) Six months
following the first presentation
there was recurrence of IAM
depicted on DWI and ADC map
A 34-year-old man with transsphinteric anal fistula of positive inflammation activity with abscess. (A)
Axial T2-weighted image shows a perianal fistula (arrow) that exhibits slightly high signal intensity.
(B and C) Axial and sagittal fat-suppression T2-weighted images show a perianal fistula (arrow) that
exhibits high signal intensity. (D) Axial diffusion tensor imaging reveals high signal intensity at the
fistula (arrow). (E) Axial apparent diffusion coefficient (ADC) map shows a value of 0.377 × 10−3 mm2/s
for the fistula. (F) Axial fractional anisotropy (FA) map shows a value of 0.073.
Inflammatory Bowel Disease DWI has been
found promising for detecting active inflammation
in patients with Crohn's disease. The reported
sensitivity and specificity are 80% and 95% . DWI
of the bowel is subject to motion and artifact from
bowel gas; therefore, glucagon and oral contrast
agents are recommended to minimize these
technical challenges. Even without bowel
preparation, MR colonography with DWI has been
found 90% sensitive and 87% specific in detecting
inflamed segments of colon in patients with
Axial T2-weighted MR image shows
fluid-filled loops of bowel (thin
arrows) in right lower quadrant with
mesenteric phlegmon (thick arrow).
Axial diffusion-weighted MR image (b
= 650 s/mm2) highlights active
inflammation in diseased bowel wall
(thin arrows), distinct from fluid
within bowel lumen (asterisk).
Restricted diffusion in mesenteric
phlegmon (thick arrow) is also
Active distal ileal Crohn’s disease. Axial diffusion weighted imaging (A) (b = 150) and (B) apparent
diffusion coefficient map as well as (C) axial and (D) coronal fat-suppressed post-gadolinium 3D-GRE
T1-weighted images. There is a long segment of distal ilial diffuse thickening associated with diffusion
restriction (A and B) as well as significant contrast enhancement (C) and vasa recta engorgement
(comb sign) (D) in keeping with active Crohn’s disease. GRE: Gradient recalled echo.
Diverticulitis: Although CT is the primary imaging
modality for the diagnosis of acute diverticulitis, this
condition can also be diagnosed with MRI as an incidental
finding or in pregnant patients. In these cases, DWI is
helpful in alerting the radiologist to the inflammation.
Many radiologists routinely recommend follow-up
colonoscopy to exclude underlying cancer, even though
this recommendation has been questioned. DWI has
potential for differentiating acute colonic diverticulitis
and malignancy, allowing this recommendation to be
eliminated. MRI with T2-weighted sequences combined
with DWI was found 100% sensitive and specific for
differentiating diverticulitis from cancer in the sigmoid
Acute sigmoid diverticulitis.
Active colonic ulcerative colitis. A: Axial diffusion-weighted imaging (b =
650 s/mm2); B: ADC map images. There is diffuse thickening involving the
colon associated wish diffuse mucosal diffusion restriction (arrows A) in
keeping with active ulcerative colitis. ADC: Analog-digital conversion.
Hepatic cyst with high signal intensity on DWI
(b50) and on ADC map (T2 shine-through).
Polycystic renal disease demonstrates high signal intensity
both on DWI (b50) and on ADC map (T2 shine-through).
The gallbladder has high signal intensity both on
DWI (b400) and on ADC map (T2 shine-through).
The bladder shows high signal intensity on
DWI (b0) and on ADC map (T2 shine-through).
The peripheral zone of the prostate can
demonstrate high signal intensity both on
DWI (b50) and on ADC map (T2 shine-through).
A hepatic nodule with typical features of adenoma
shows high signal intensity on DWI (b400) and low
ADC values, thus demonstrating restricted diffusion.
A hepatic nodule with typical features of focal nodular
hyperplasia shows restricted diffusion, with high signal
intensity on DWI (b400 in this case) and low ADC values.
Hepatic hemangioma with restricted diffusion, demonstrating
high signal intensity on DWI (b400) and low ADC values.
at the DWI.
Incidental mass in tail of pancreas, related
to intra-pancreatic accessory spleen.
Role of DWI as a biomarker
Hepatic carcinogenesis is a multistep process; with progression from cirrhotic nodules to
dysplastic nodules to well differentiated HCC. Hyperintensity on DWI in hypovascular nodules
in patients with cirrhosis has been shown to predict progression to hypervascular HCC.
DWI can predict the histopathologic grade of HCC. There is an inverse correlation between
tumor grade and ADC value, with poorly differentiated HCC showing more restricted
diffusion than well differentiated HCC although one study showed no significant
association between DWI and HCC tumor grade. DWI shows promise as an imaging
biomarker, since restricted diffusion can indicate presence of progenitor cell markers,
vascular endothelial growth factor (VEGF) expression, and microvascular invasion
Hepatocellular carcinoma in an 81-year-old woman. (a) Gadolinium-enhanced T1-weighted MR image shows a hypervascular mass (arrow). (b) On a
fat-suppressed fast spin-echo T2-weighted MR image, the mass is slightly hyperintense (arrow). (c) Diffusion-weighted image (b = 500 sec/mm2)
shows the mass with high signal intensity (arrow). (d) On an ADC map, the mass demonstrates restricted diffusion (arrow).
A 66-year-old lady with multifocal infiltrative hepatocellular carcinoma with improved detection on diffusion-
weighted imaging. (A) Axial T2 weighted image demonstrates multifocal areas of T2 hyperintense masses (white
arrows) which demonstrate heterogeneous arterial hyperenhancement on post gadolinium late arterial phase images
(B) and washout appearance on portal venous phase images (C). (D) Axial DWI image at b-600 and (E) ADC image
show that these masses demonstrate restricted diffusion and are better appreciated than the dynamic phase images.
Serum Alpha feto-protein value of 1552. DWI: Diffusion-weighted imaging.
Multiplanar images through the liver in a patient with hepato-cholangio-carcinoma status post left hepatectomy. A lesion
adjacent to a vessel is hyperintense on DWI axial (A) and coronal (B) images. The lesion is dark on ADC map (C), indicating
restricted diffusion. Lesion is more apparent on DWI images than post-contrast axial (D), and T2 axial (E) and coronal (F)
images; this is due to proximity of the lesion to the hepatic vein as well demonstrated in the coronal DWI (D).
Axial MRI images through the liver demonstrating a small simple cyst. A
subcentimeter lesion is present in hepatic segment 7; the lesion demonstrates
high signal intensity on T2 weighted images (A) and b 500 s/mm2 DWI (B).
However, it is bright on ADC map (C) indicating high diffusion consistent with
T2 shine through phenomena. Shine through phenomena is not rare in cysts.
Value of diffusion-weighted magnetic resonance imaging in lesion detection in a 51-year-old male with metastatic
leiomyosarcoma of the thigh. A: Axial contrast enhanced CT scan demonstrated a subtle hypodensity in the right
lobe of liver (black arrow); B: Axial post gadolinium T1-weighted MR image demonstrates a single metastatic
lesion (black arrow); C-E: DW-MR image at b-600 demonstrates additional lesions (white arrows).
DW-MR: Diffusion-weighted magnetic resonance; CT: Computed tomography.
Biopsy-proven cholangiocarcinoma in posterior right hepatic lobe adjacent to inferior vena cava.
Lesion (arrow) nearly isointense to background liver on axial T2-weighted single-shot fast spin-echo image (A) is well
shown on low-b-value diffusion-weighted (b = 50) image (B). Retained signal on high-b-value (b800) image (C)
suggests solid lesion, which as new finding in setting of cirrhosis is worrisome for hepatocellular carcinoma. Note
abdominal ascites (asterisk), which decreases in signal intensity on high-b-value images, suggestive of simple fluid.
This fluid was bright on ADC map (D). Dynamic imaging was not performed due to contraindication to gadolinium.
This example also shows potential inconspicuity of solid lesion on ADC map (D) on background of cirrhotic liver.
Hemorrhagic cyst of the kidney showing restricted diffusion:
high signal intensity on DWI (b800) and low ADC values.
Perirenal hematoma showing restricted diffusion: high signal
intensity on DWI (b800) and low ADC values.
Coronal T1-weighted 3D spoiled gradient-echo images obtained before (A) and after (B) gadolinium administration show left renal mass (arrow) with
subtle enhancement. Lesion was iso- to slightly hypointense to kidney on low-b-value images (not shown) but is hyperintense compared with renal
parenchyma on high-b-value diffusion-weighted image (C) and hypointense on apparent diffusion coefficient map (D). Findings are consistent with
restricted diffusion, confirming solid neoplasm in this context and papillary RCC was confirmed at histopathology after partial nephrectomy.
Renal cell carcinoma in a 54-year-old woman.
(a) Fast spin-echo T2-weighted MR image
shows a mass (arrow) that arises from the left
kidney. The mass demonstrates intermediate
signal intensity, a finding that is consistent
with a solid mass or hemorrhagic cyst. (b)
Axial diffusion-weighted image (b = 500
sec/mm2) shows the mass with high signal
intensity (arrow). (c) On an axial ADC map, the
mass (arrow) demonstrates low signal
intensity (restricted diffusion), a finding that is
consistent with a solid tumor.
Normal lateroaortic lymph node showing restricted diffusion:
high signal intensity on DWI (b800) and low ADC values.
Cancer esophagus with porta hepatis lymph node metastasis.
Hepatic metastasis from colon adenocarcinoma with necrotic
center, where the ADC values are significantly higher.
Adrenal metastasis from renal cell carcinoma shows very high
signal intensity on DWI (b800) and low ADC values.
Normal proliferative endometrium can
show restricted diffusion (high signal
intensity on DWI b50 and low ADC values)
Uterine leiomyoma showing low signal intensity both on
T2 weighted DWI and on ADC map (T2 blackout effect).
Mucinous tumour of the rectum shows high signal intensity
both on DWI (b50) and ADC map - T2 shine through.
Rectal cancer shows high signal intensity
even at very high b values (b1000).
Stage T3 rectal cancer. A and B: Axial high-resolution T2-weighted images as well as axial
(C) diffusion-weighted imaging (b = 650 s/mm2) and (D) ADC map images. There is a large
polypoidal mass lesion arising from the right anterolateral lower rectal wall (A and B)
with two foci of tumoral extension beyond the low-signal serosal layer (arrows, B) that
show diffusion restriction (C and D) in keeping with stage T3 rectal tumor. ADC: Analog-
Anal canal cancer shows high signal intensity on
DWI (b800) and low ADC values.
Prostate cancer in a 64-year-old man. (a)
On an axial T2-weighted MR image
obtained with an endorectal coil, the
peripheral zone of the prostate gland
appears normal (ie, has high signal
intensity), but a questionable focus of
hypointensity is seen in the anterior left
central portion of the gland (arrow). (b)
Axial ADC map more clearly depicts the
questionable area as a hypointense focal
region of restricted diffusion (arrow).