Whole-body MRI using a sliding table and repositioning surface coil approach.

OBJECTIVE: To introduce and assess a new way of performing whole-body magnetic resonance imaging (MRI) using a non-integrated surface coil approach as available on most clinical MRI systems worldwide. METHODS: Ten consecutive asymptomatic subjects prospectively underwent whole-body MRI for health screening. Whole-body MRI included T1-, T2- and diffusion-weighted sequences, and was performed using a non-integrated surface coil to image four different stations without patient repositioning. The four separately acquired stations were merged, creating seamless coronal whole-body T1-, T2- and diffusion-weighted images. Anatomical alignment, image quality at the boundaries of adjacent stations, and overall image quality of all stations were qualitatively assessed. RESULTS: The average time (+/-SD) taken to change the surface coil from one station to the next station was 53.8 (+/-7.1) s. The average total extra examination time +/- SD was 2 min 41.4 s (+/-15.3 s). Anatomical alignment, image quality at the boundaries of adjacent stations, and overall image quality of all stations of T1-, T2- and diffusion-weighted whole-body MRI were overall graded as "good" to "excellent". CONCLUSION: This study shows that a time-efficient and high-quality whole-body MRI examination can easily be performed by using a non-integrated sliding surface coil approach.

Pulmonary varix mimicking arteriovenous malformation.

We report here a case of a 44-year-old female with a pulmonary varix. The patient was asymptomatic; a routine chest X-ray incidentally revealed a serpiginous mass in the left hilar region. Computed tomography revealed a serpiginous, dilated vascular structure in the left upper lobe that continued into the lower lobe and was suggestive of an arteriovenous malformation. Pulmonary angiography revealed no arterial abnormality; however, the filling of an abnormally dilated pulmonary vein was observed. Angiography is considered to be the most useful method for the confirmatory diagnosis of pulmonary varices.

The detection rates and tumor clinical/pathological stages of whole-body FDG-PET cancer screening.

OBJECTIVE: FDG-PET has been used for cancer screening, mainly in East-Asia, and cancers are found not infrequently. However, their stages have not been clarified. We examined the detection rates of various cancers using whole-body PET for the screening of cancers in asymptomatic individuals, focusing on their clinical and pathological stages. METHODS: Whole-body PET was obtained as a part of our cancer screening program among 3,426 healthy subjects. All subjects participated in a course of PET examination in conjunction with conventional examinations including a medical questionnaire, tumor markers, immunological fecal occult blood test, neck and abdominal ultrasonography and whole body computed tomography. A diagnosis and staging was obtained by an analysis of the pathological findings or by an analysis of the clinical follow-up data. RESULTS: Malignant tumors were discovered in 65 lesions found in 3,426 participants (1.90%). The PET findings were true-positive in 46 of the 65 cancer cases. The cancers were found in the following organs: the colon 14; thyroid gland 10; stomach 7; lung 5; liver 3; breast 2; and one each in the kidney, gallbladder, esophagus, pancreas and retroperitoneum. The stages were as follows: stage 0 5, stage I 17, stage II 10, stage III 7, and stage IV 6. One was an unknown primary. There were 19 false-negative findings (0.6%) on PET. Six cancers (0.18%) were missed in our screening program. CONCLUSIONS: PET imaging has the potential to detect a wide variety of cancers at potentially curative stages. Most PET-negative cancers are early stage cancers, and thus can be detected using other conventional examinations such as endoscopy.

Intravascular ultrasound imaging in the assessment of atherosclerotic plaques in rabbit abdominal aorta: comparison with histologic findings.

RATIONALE AND OBJECTIVES: To examine the correlation between the echogenicity and the components of atherosclerotic plaques in rabbit. METHODS: The atherosclerotic plaque formation in the abdominal aortas of hyperlipidemic or normolipidemic rabbits was stimulated by inserting polyethylene tubing. Intravascular ultrasound (30-MHz, 4.5 F catheter) investigation was performed at locations in the vessel. The intravascular ultrasound images of the plaques were evaluated and compared with the histologic findings. RESULTS: Ultrasound images delineated areas showing hyperechoic or hypoechoic ultrasound beams in the plaques. Histologic studies revealed that the hyperechoic areas were closely associated with a dense fibrous extracellular matrix, whereas the hypoechoic areas corresponded to lesions showing a marked accumulation of foamy macrophages or proteoglycan-rich loose myxoid extracellular matrix with smooth muscle cell proliferation. CONCLUSION: A good correlation between ultrasound images and histologic features was observed. These results suggest that intravascular ultrasound imaging could provide useful information for assessing the tissue characteristics of atherosclerotic lesions.

Complementary roles of whole-body diffusion-weighted MRI and 18F-FDG PET: the state of the art and potential applications.

(18)F-FDG PET is an established functional imaging modality for the evaluation of human disease. Diffusion-weighted MRI (DWI) is another rapidly evolving functional imaging modality that can be used to evaluate oncologic and nononcologic lesions throughout the body. The information provided by (18)F-FDG PET and DWI can be complementary, because the 2 methods are based on completely different biophysical underpinnings. This article will describe the basic principles, clinical applications, and limitations of DWI. In addition, the available evidence that correlates and compares (18)F-FDG PET and DWI will be reviewed.

Assessment of coronary artery disease using magnetic resonance coronary angiography: a national multicenter trial.

OBJECTIVES: This national multicenter study determined the diagnostic performance of 1.5-T whole-heart coronary magnetic resonance angiography (MRA) in patients with suspected coronary artery disease (CAD). BACKGROUND: Whole-heart coronary MRA using steady-state free precession allows noninvasive detection of CAD without the administration of contrast medium. However, the accuracy of this approach has not been determined in a multicenter trial. METHODS: Using a 1.5-T magnetic resonance imaging unit, free-breathing steady-state free precession whole-heart coronary MRA images were acquired for 138 patients with suspected CAD at 7 hospitals. The accuracy of MRA for detecting a ≥ 50% reduction in diameter was determined using X-ray coronary angiography as the reference method. RESULTS: Acquisition of whole-heart coronary MRA images was performed in 127 (92%) of 138 patients with an average imaging time of 9.5 ± 3.5 min. The areas under the receiver-operator characteristic curve from MRA images according to vessel- and patient-based analyses were 0.91 (95% confidence interval [CI]: 0.87 to 0.95) and 0.87 (95% CI: 0.81 to 0.93), respectively. The sensitivity, specificity, positive and negative predictive values, and accuracy of MRA according to a patient-based analysis were 88% (49 of 56, 95% CI: 75% to 94%), 72% (51 of 71, 95% CI: 60% to 82%), 71% (49 of 69, 95% CI: 59% to 81%), 88% (51 of 58, 95% CI: 76% to 95%), and 79% (100 of 127, 95% CI: 72% to 86%), respectively. CONCLUSIONS: Non-contrast-enhanced whole-heart coronary MRA at 1.5-T can noninvasively detect significant CAD with high sensitivity and moderate specificity. A negative predictive value of 88% indicates that whole-heart coronary MRA can rule out CAD.

Comparison of diffusion-weighted MRI and 2-[fluorine-18]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for detecting primary colorectal cancer and regional lymph node metastases.

PURPOSE: To examine the usefulness of diffusion-weighted MRI (DW-MRI) for the detection of both primary colorectal cancer and regional lymph node metastases, and compare its performance with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in the same patients. MATERIALS AND METHODS: We studied 25 patients with known colorectal cancer. All underwent both DW-MRI and FDG-PET studies. The images were retrospectively assessed by visual inspection and the imaging findings were compared with histopathological findings on surgical specimens. RESULTS: Of the 27 primary colorectal lesions surgically excised in 25 patients, 23 (85.2%) were true-positive on both DW-MRI and FDG-PET. Two cancers were false-negative on DW-MRI but true-positive on FDG-PET, and two were false-negative on both DW-MRI and FDG-PET. With respect to the detectability of metastatic lymph nodes, DW-MRI and FDG-PET manifested a sensitivity of 80% (8/10) and 30.0% (3/10), a specificity of 76.9% (10/13) and 100% (13/13), and an accuracy of 78.3% (18/23) and 69.6% (16/23), respectively. CONCLUSION: DW-MRI is inferior to FDG-PET for the detection of primary lesions, but superior for the detection of lymph node metastases.

Whole-body diffusion-weighted magnetic resonance imaging.

Diffusion-weighted magnetic resonance imaging (DWI) provides information on the diffusivity of water molecules in the human body. Technological advances and the development of the concept of diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) have opened the path for routine clinical whole-body DWI. Whole-body DWI allows detection and characterization of both oncological and non-oncological lesions throughout the entire body. This article reviews the basic principles of DWI and the development of whole-body DWI, illustrates its potential clinical applications, and discusses its limitations and challenges.

Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS): features and potential applications in oncology.

Diffusion-weighted magnetic resonance imaging (DWI) provides functional information and can be used for the detection and characterization of pathologic processes, including malignant tumors. The recently introduced concept of "diffusion-weighted whole-body imaging with background body signal suppression" (DWIBS) now allows acquisition of volumetric diffusion-weighted images of the entire body. This new concept has unique features different from conventional DWI and may play an important role in whole-body oncological imaging. This review describes and illustrates the basics of DWI, the features of DWIBS, and its potential applications in oncology.