1. Diffusion-Weighted Magnetic Resonance Imaging in the Upper Abdomen: Technical Issues and Clinical Applications 
Leonardo K. Bittencourt, MD, Celso Matos, MD, Antonio C. Coutinho, MD 
Magnetic Resonance Imaging Clinics 
Volume 19, Issue 1, Pages (February 2011)
DOI: /j.mric
Copyright © 2011 Elsevier Inc. Terms and Conditions

2. Fig. 1
The influence of the b-value on the signal intensities of liver structures: (A) b-value = 0 s/mm2, showing both blood vessels (arrowhead) and biliary ducts (arrow) with high signal intensity, overlaid on liver parenchyma with intermediate signal intensity. When the b-value is equal to 0, there is maximum overall SNR but also a maximal T2 shine-through effect; (B) with a b-value of 100 s/mm2, structures with blood flow have a dark signal caused by their markedly unimpeded diffusion (the so-called black-blood effect). Resting or slow-flowing fluids, such as within the biliary ducts (arrow) or simple cysts, retain high signal intensities, as do most benign and malignant focal lesions, which is useful for lesion detection; and (C) with a b-value of 1000 s/mm2, fluid structures and most benign lesions have dark signal intensities. On high b-values, the diffusion weighting is maximized and the T2 shine-through effect is minimized, but at the expense of a significantly low SNR when compared with low b-values.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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3. Fig. 2
The usefulness of low b-value images in the detection of liver lesions. In this 62-year-old female patient with metastatic pancreatic adenocarcinoma, the low b-value images (A), b = 100 s/mm2, depicted more lesions with smaller dimensions and better conspicuity than did fat-suppressed T2w images (B).
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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4. Fig. 3
An 18-year-old female patient with acute myeloid leukemia presented with sepsis: (A) the low b-value images (b = 50 s/mm2) depicted several millimetric hyperintense foci that were diffusely distributed in the liver parenchyma (arrowheads), which were better displayed using DWI than using fat-suppressed T2w images (arrowhead in B), T2w images (C), or delayed-phase postgadolinium T1w (arrowheads in D). These lesions were deemed to be suspicious for liver microabscesses, probably caused by fungal infection. The blood cultures were positive for Candida albicans and the patient eventually died of the infection and sepsis.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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5. Fig. 4
Motion artifacts on the left liver lobe. In this 42-year-old male patient with disseminated HCC, there were 2 bulky lesions detected on fat-suppressed T2w images (arrow and arrowhead in A), but only the one in the right liver lobe was detected using DWI (arrow in B). The left liver is completely blurred from motion artifacts, caused by its proximity to the heart.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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6. Fig. 5
Lesion characterization using DWI based on visual assessment. In this 74-year-old female patient with metastatic pancreatic adenocarcinoma, the fat-suppressed T2w image (A) shows a markedly hyperintense cystic lesion on segment IV (arrow) and 3 ill-defined, mildly hyperintense solid lesions on segments II and VII (arrowheads). The cystic lesion is also hyperintense on low b-value DWI (B, b = 0 s/mm2), but shows a significant signal drop on high b-value images (C, b = 1000 s/mm2). In contrast, the metastatic lesions are mildly hyperintense on low b-value images (B), but retain high signal intensity in comparison with the background on high b-value images (C).
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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7. Fig. 6
The ADC map from the same patient as in Fig. 5, depicting the metastatic lesions as dark areas (arrowheads), with a mean ADC of 0.95 (±0.01)×10−3 mm/s2. The cystic lesion (arrow) is shown as a bright area and has a mean ADC of 2.50 (±0.07)×10−3 mm/s2.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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8. Fig. 7
Comparison between the ADC values of different solid lesions, marked by the arrows on the corresponding images: (A) hemangioma (ADC 2.38 ± 0.24×10−3 mm/s2); (B) another hemangioma (1.42 ± 0.16×10−3 mm/s2); (C) focal nodular hyperplasia (1.23 ± 0.7×10−3 mm/s2); (D) hepatocellular adenoma (0.91 ± 0.14×10−3 m/s2); (E) intrahepatic cholangiocarcinoma (0.92 ± 0.09×10−3 mm/s2); and (F) hepatocellular carcinoma (0.88 ± 0.14×10−3 mm/s2).
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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9. Fig. 8
Effects of cystic or necrotic components on the ADC measurement of solid lesions. (A) Delayed-phase postgadolinium fat-suppressed T1w image depicting a large mass with central necrosis or cystic degeneration in a 57-year-old male patient with metastatic colonic carcinoma (arrow). The lesion shows high signal intensity on DWI with b = 0 s/mm2 (B), but there is a marked signal drop on the cystic component at b = 1000 s/mm2, whereas the peripheral solid component remains with high signal intensity (C). The ADC map (D) shows a ringlike dark area, corresponding to the enhancing solid component. In these cases, adequate region of interest placement and measurement standardization are essential because, although the ADC of the whole lesion shaded area in (E) was 1.82 (±0.57)×10−3 mm/s2, the ADC value that measured only on the solid component (shaded area in F) was as low as 1.20 (±0.25)×10−3 mm/s2.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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10. Fig. 9
Gallbladder cancer as shown by DWI. (A) T2w image showing a lobulated hyperintense mass originating from the gallbladder fossa and infiltrating the adjacent liver parenchyma (arrow), which is also seen as a hyperintense lesion on high b-value diffusion-weighted images (arrow in B). Note the satellite nodule (arrowhead in B), which was not seen on the T2w images. On the ADC map (C), the lesion shows low signal intensity and the ADC value inside the white outline was 0.84 (±0.15)×10−3 mm/s2.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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11. Fig. 10
Ascending cholangitis seen using DWI. (A) T2w image in a 48-year-old female patient after enterobiliary anastomosis, showing an ill-defined, mildly hyperintense, peripheral triangular area on segment V (arrows), surrounding dilated small intrahepatic biliary branches. On the arterial phase after gadolinium injection (B), there is an early enhancement of this same area (arrows). Diffusion-weighted images with low and high b-values (C and D, respectively) also show high signal intensity in this area (arrows), but additionally depict subtle linear hyperintensities along more proximal biliary branches (asterisks in C and D). This finding was believed to represent inflammatory content, suggesting ascending cholangitis. The main left biliary duct (arrowhead in C), which is seen as a hyperintense structure in (C), shows marked signal drop in (D), indicating simple fluid content. The diagnosis was confirmed and the patient was discharged as asymptomatic after treatment. (E) The fused image containing the high b-value sequence (orange) overlaid on fat-suppressed T2w images is a way of showing with greater certainty that the anatomic findings from conventional sequences (arrows) match the functional findings of DWI.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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12. Fig. 11
Papillary RCC. This 49-year-old female patient had an incidental solid renal lesion detected in a previous ultrasound scan. In the T2w images (A) there is a discrete hypointense round mass (arrow), which shows no chemical-shift artifacts or signal drop at opposed-phase T1W images (B) and exhibits mild enhancement on the late phase after gadolinium (C). Using DWI, the lesion is hypointense to the renal parenchyma on low b-values (D), but maintains high signal intensity with high b-values (E). The measured ADC (F) was 0.71 (±0.07)×10−3 mm/s2.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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13. Fig. 12
Clear-cell RCC (compare with Fig. 11) in a case of an incidental renal mass in a 39-year-old female patient. The T2w images (A) show a heterogeneous partially defined solid mass (arrows), with early and intense enhancement on the arterial phase after gadolinium (B). The mass was hypointense to the renal parenchyma on low b-values (C), but seemed almost isointense with high b-values (D). The measured ADC (E) was 1.46 (±0.11)×10−3 mm/s2. In both cases, the renal parenchyma had ADC values greater than 1.80×10−3 mm/s2.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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14. Fig. 13
Cystic RCC: importance of the region of interest placement on ADC measurements. This 79-year-old female patient presented with a complex cystic renal mass (arrows in A) with thick enhancing septa and a mural nodule (arrowheads in A), characterized as Bosniak type IV. On DWI, the cystic content showed unimpeded diffusion, with high signal intensity when low b-values were used (B) and low signal intensity when high b-values were used (B). Conversely, the mural nodule (arrow in B and A) showed restricted diffusion, with evident hyperintensity when high b-values were used (C). When measuring the ADC (D), if the whole lesion was included in the region of interest, the value was as high as 2.31 (±0.33)×10−3 mm/s2. In contrast, if only the mural nodule was considered, the ADC values dropped to 1.70 (±0.19)×10−3 mm/s2.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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15. Fig. 14
Pancreatic adenocarcinoma in a 62-year-old female patient. In T2w images (A), there is an ill-defined heterogeneous solid mass on the pancreatic body (black arrows), determining obstruction, and upstream dilatation of the main pancreatic duct (arrowhead). Liver metastases (white arrows) are also evident. Using DWI, both the pancreatic mass and the liver metastases show high signal intensity with low b-values (B) and retain high signal intensity with high b-values (C). The diffusion-weighted images seem to detect more liver metastases than the T2w sequence of practically the same location. The ADC values (D) measured for the pancreatic mass and the metastases are 1.19 (±0.14)×10−3 mm/s2 and 0.84 (±0.06)×10−3 mm/s2 respectively.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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16. Fig. 15
Pancreatic neuroendocrine tumor diagnosed through DWI. T2w image (A) showing an ill-defined, slightly hyperintense focal lesion on the posterior aspect of the pancreatic body (arrow), that was not visible in the arterial phase after gadolinium injection (B). In high b-value DWI (C) the lesion is well seen as a hyperintense focus, in keeping with restricted diffusion. The diagnosis of a hypovascular neuroendocrine tumor was surgically confirmed.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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17. Fig. 16
Chronic pancreatitis with superimposed acute pancreatitis. (A) T2w image of a patient with chronic pancreatitis presenting with abdominal pain, showing an irregularly dilated main pancreatic duct (arrowhead). There is mild parenchymal hyperintensity on the tail (arrow), and an irregular cystic area (asterisk) is noted. High b-value DWI (B) reveals high signal intensity involving the pancreatic tail (arrows), representing a focus of acute pancreatitis. The cystic lesion shows markedly restricted diffusion (arrowhead), probably related to focal necrosis or a pseudocyst.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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18. Fig. 17
Autoimmune pancreatitis, before and after treatment. In pretreatment T2w images (A), the pancreatic head appears mildly enlarged and slightly hyperintense (arrow). High b-value DWI (B) shows markedly high signal intensity on the same area (arrow), with an ADC value of 0.96×10−3 mm/s2 (C). Two weeks after corticotherapy, the T2w image (D) shows partial regression on the pancreatic head swelling, with lower signal intensity (arrow). The high b-value DWI (E) remains with correspondingly high signal intensity (arrow), although with an increase on the ADC value (F), which has risen to 1.09×10−3 mm/s2.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
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19. Fig. 18
Intrapancreatic ectopic spleen seen using DWI. (A) T2w image of a 55-year-old male patient showing a discrete solid mass at the tip of the pancreatic tail, slightly hyperintense to the pancreas (arrowheads). Usually, intrapancreatic ectopic spleens can be identified easily in the arterial phase after gadolinium (B), showing an enhancement pattern similar to that of the original spleen, but, in this case, there was no characteristic hyperenhancement in the mass (arrowheads). Using DWI (C), the nodule appeared hyperintense with high b-values (arrowhead), always resembling the signal intensity of the spleen. The lesion showed no significant growth in successive follow-up examinations and was, therefore, characterized as an ectopic spleen.
Magnetic Resonance Imaging Clinics  , DOI: ( /j.mric )
Copyright © 2011 Elsevier Inc. Terms and Conditions