Intracranial Flow Velocity Quantification Using Non-Contrast Four-Dimensional Flow MRI: A Prospective Comparative Study with Transcranial Doppler Ultrasound

Four-dimensional (4D) flow magnetic resonance imaging (MRI) allows three-dimensional velocity encoding to measure blood flow in a single scan, regardless of the intracranial artery direction. We compared blood flow velocity quantification by non-contrast 4D flow MRI and by transcranial Doppler ultrasound (TCD), the most widely used modality for measuring velocity. Twenty-two patients underwent both TCD and non-contrast 4D flow MRI. The mean time interval between TCD and non-contrast 4D flow MRI was 0.7 days. Subsegmental velocities were measured bilaterally in the middle cerebral and basilar arteries using TCD and non-contrast 4D flow MRI. Intracranial velocity measurements using TCD and non-contrast 4D flow MRI demonstrated a strong correlation in the bilateral M1, especially at the proximal segment (right r = 0.74, left r = 0.78; all p < 0.001). Mean velocities acquired with 4D flow MRI were approximately 8 to 10% lower than those acquired with TCD according to the location of M1. Intracranial arterial flow measurements estimated using non-contrast 4D flow MRI and TCD showed strong correlation. 4D flow MRI enables simultaneous assessment of vascular morphology and quantitative hemodynamic measurement, providing three-dimensional blood flow visualization. 4D flow MRI is a clinically useful sequence with a promising role in cerebrovascular disease

MALT Lymphoma of the Tongue in a Patient with Sjögren’s Syndrome: A Case Report and Literature Review

Sjögren’s syndrome (SS) is a systemic chronic autoimmune disorder characterized by lymphocytic infiltration of the exocrine glands, as well as oral and ocular dryness. Among the late complications, malignant lymphoma is the most serious complication of SS. The risk of lymphoma in patients with SS has been estimated to be approximately 7–19 times higher than that in a generally healthy population. Although various histologic subtypes of lymphoma can occur in patients with SS, mucosa-associated lymphoid tissue (MALT) lymphoma accounts for 48–75% of malignant lymphomas that are frequently located in the parotid gland. However, MALT lymphoma affecting the tongue in patients with SS is extremely rare. Here, we share our experience with a unique case of MALT lymphoma of the tongue, originating from the minor salivary gland tissue in a patient with SS. Through this case report, we emphasize that MALT lymphoma should be considered in the differential diagnosis of a tongue mass in patients with SS

Computer-aided detection of brain metastasis on 3D MR imaging: Observer performance study.

To assess the effect of computer-aided detection (CAD) of brain metastasis (BM) on radiologists' diagnostic performance in interpreting three-dimensional brain magnetic resonance (MR) imaging using follow-up imaging and consensus as the reference standard.The institutional review board approved this retrospective study. The study cohort consisted of 110 consecutive patients with BM and 30 patients without BM. The training data set included MR images of 80 patients with 450 BM nodules. The test set included MR images of 30 patients with 134 BM nodules and 30 patients without BM. We developed a CAD system for BM detection using template-matching and K-means clustering algorithms for candidate detection and an artificial neural network for false-positive reduction. Four reviewers (two neuroradiologists and two radiology residents) interpreted the test set images before and after the use of CAD in a sequential manner. The sensitivity, false positive (FP) per case, and reading time were analyzed. A jackknife free-response receiver operating characteristic (JAFROC) method was used to determine the improvement in the diagnostic accuracy.The sensitivity of CAD was 87.3% with an FP per case of 302.4. CAD significantly improved the diagnostic performance of the four reviewers with a figure-of-merit (FOM) of 0.874 (without CAD) vs. 0.898 (with CAD) according to JAFROC analysis (p < 0.01). Statistically significant improvement was noted only for less-experienced reviewers (FOM without vs. with CAD, 0.834 vs. 0.877, p < 0.01). The additional time required to review the CAD results was approximately 72 sec (40% of the total review time).CAD as a second reader helps radiologists improve their diagnostic performance in the detection of BM on MR imaging, particularly for less-experienced reviewers

Example of an ANN for FP reduction of BM candidates using computer features.

<p>Example of an ANN for FP reduction of BM candidates using computer features.</p

3D gradient-echo contrast-enhanced T1-weighted MR images in an 81-year-old female patient with metastatic lung cancer.

<p>A and B: Axial (A) and coronal (B) images show a tiny enhancing nodule at the left inferior temporal gyrus (arrowhead). This nodule was missed by all four reviewers but was successfully detected by CAD. C: On the navigation MR image for a gamma-knife surgery performed 2 days after (A) and (B), the nodule showed no interval changes. D: On the follow-up MR image taken after 3 months, the nodule disappeared.</p

Examples of CAD results using algorithm A.

<p>A–D: Examples of the correct detection of BM by CAD software. E–H: Examples of the incorrect detection (FPs) by CAD software. Common sources of FPs included the cortical vessel (F), dural sinus (G), and choroid plexus (H).</p

Bar graph of the nodule size distributions in the training and test sets.

<p>The relative frequency of nodules with diameters of 1 to 3 mm differed significantly between the two groups (p = 0.01).</p

Flow diagram for patient selection.

<p>The diagram shows the initial case selection and final distribution of study cases into the training set and test set. Jan = January, Mar = March.</p

Comparison of the reviewers’ nodule detection performances.

<p>Comparison of the reviewers’ nodule detection performances.</p