Diffusion-weighted Imaging Intensity Research Articles

Kanser Tanısında Tüm Vucut MR ile PET-CT Karşılaştırması

Objective: Whole body diffusion-weighted imaging (DWI) has been increasingly used in oncological cases for detection and characterization of tumors and monitoring of treatment response. We compared the tumor detection capacity and diagnostic accuracy of DWI with positron emission tomography/computed tomography (PET/CT), which is regarded as the gold standard. Materials and Methods: The study included 29 adult patients (13 men and 16 women) aged between 38 and 86 years who had various types of cancer, and for whom PET/CT was indicated for staging or evaluating treatment response. A total of 240 lesions that were positive in FDG-PET/CT were identified in the DWI images, and DWI signal intensity and apparent diffusion coefficient (ADC) value were measured for each lesion. SUVmax, ADC, and DWI intensity values of PET-positive lesions and lesion areas for both methods were compared using Mann-Whitney U test and Spearman correlation test. Results: SUVmax and DWI intensities of the lesions showed significant correlation (Spearman correlation coefficient= -0.296, p<0.0001). When we analyzed whether lesion size was associated with SUVmax, ADC, or DWI intensity, we found a correlation between lesion diameter and DWI intensity (r=-0.30; p=0.0001). Conclusion: The DWI was generally correlated with PET/CT with very close specificity and sensitivity values between the two methods. Whole body DWI can be used as an alternative or complementary to PET/CT in investigation and follow-up of oncological cases.

NI-11 Clinical significance of intracystic diffusion hyperintensity lesions remaining after treatment of intracranial germ cell tumor

Background and purpose: About 30% of intracranial germ cell tumors are mixed germ cell tumors and teratomas are often found as those components. Intense chemoradiotherapy is performed according to the malignancy of the histopathology, but high-intensity lesion inside the cystic tumor on diffusion weighted imaging (DWI) sometimes remains after completion of the chemoradiotherapy. In this study, we examined the clinical significance of the DWI high-intensity lesion remaining in the cyst. METHODS: Five patients after initial chemoradiotherapy were resected residual tumor by craniotomy at our hospital from 2009 to 2019. Preoperative gadolinium-enhanced MRI defined the non-contrast-enhanced part of the tumor as intracystic, and DWI intensity was classified by its look as low-intensity, equal-intensity, and high-intensity compared to the cortex of the same slice. DWI signals in the solid area, cyst wall, and cyst were evaluated. Results: All cases were mature teratoma in histopathology, and no other tumor components were observed. On DWI, the cyst wall and solid part were visualized with low signal. High-intensity lesions and equal-intensity lesions in the cyst cavity were found in 3 and 1 cases, respectively. In these cases, pathological findings revealed a keratin-like substance in the cyst. Discussion: The intracystic high and equal intensity lesions on DWI removed after completion of chemoradiotherapy are considered to reflect the keratin-like component of mature teratoma. If DWI- high intensity and equal intensity lesions remain in the cyst of the tumor after the completion of chemoradiotherapy, tumor shrinkage cannot be expected even if the chemotherapy is strengthened. In such cases, we should consider to removing them by surgery. Conclusion: When DWI high and equal intensity lesions are found in the cysts of tumors remaining after chemoradiotherapy for intracranial germ tumors, it is possible that mature teratoma remains.

Mapping a Reliable Stroke Onset Time Course Using Signal Intensity on DWI Scans.

Identifying a last known well (LKW) time surrogate for acute stroke is vital to increase stroke treatment. Diffusion-weighted imaging (DWI) signal intensity initially increases from onset of stroke but mapping a reliable time course to the signal intensity has not been demonstrated. We retrospectively reviewed stroke code patients between 1/2016 and 6/2017 from the prospective; Institutional review board (IRB) approved University of California San Diego Stroke Registry. Patients who had magnetic resonance imaging of brain from onset, with or without intervention, are included. All ischemic strokes were confirmed and timing from onset to imaging was calculated. Raw DWI intensity is measured using IMPAX software and compared to contralateral side for control for a relative DWI intensity (rDWI). LKW and magnetic resonance imaging (MRI) time were collected by chart review. Correlation is assessed using Pearson correlation coefficient between DWI intensity, rDWI, and time to MRI imaging. 1.5T, 3T, and combined modalities were examined. Seventy-eight patients were included in this analysis. Overall, there was statistically significant positive correlation (.53, P < .001) between DWI intensity and LKW time irrespective of scanner strength. Using 1.5T analyses, there was good correlation (.46, P < .001). 3T MRI analysis further showed comparatively stronger positive correlation (.66, P < .001). There is good correlation between DWI intensity and minutes from onset to MRI. This suggests a time-dependent DWI intensity response and supports the potential use of DWI intensity measurements to extrapolate an LKW time. Further studies are being pursued to increase both experience and generalizability.

Diagnosis of lateral pelvic lymph node metastasis of T1 lower rectal cancer using diffusion-weighted magnetic resonance imaging: A case report with lateral pelvic lymph node dissection of lower rectal cancer.

The present study presented a 35-year-old female patient in whom fecal occult blood was detected in a medical check-up. Colonoscopy revealed a superficial elevated-type tumor with central depression in the lower rectum. The tumor was diagnosed as T1 deep invasive cancer. No swollen lymph nodes or distant metastasis were found on computed tomography or [18F]-fluorodeoxyglucose-positron emission tomography with computed tomography. However, a swollen right lateral pelvic lymph node (LPLN; short axis 4 mm) was revealed on magnetic resonance imaging (MRI). This lymph node exhibited high intensity on diffusion-weighted imaging (DWI), suggesting metastasis. Low anterior resection, regional lymph node dissection and right LPLN dissection (LPLD) were performed. Histological analysis revealed metastasis in the right LPLN, as suggested by the high DWI intensity. The indication for LPLD in the current Japanese guidelines is based on the tumor location and depth of invasion (≥T3), however, not on the status of LPLN metastasis in pre-operative evaluation. The present case was cT1, which is not included in this indication. DWI is sensitive for the diagnosis of lymph node metastasis of colorectal cancer, although inflammation-induced swelling of lymph nodes in advanced rectal cancer may cause a false-positive result, which is uncommon in T1 cases. Therefore, an LPLN with a high intensity DWI signal in T1 cases is likely to be metastasis-positive. Pre-operative DWI-MRI may be useful for identifying LPLN metastasis when planning the treatment strategy in these cases. The present study suggested reinvestigation of the indication for LPLD with inclusion of LPLN status on pre-operative imaging.

A Novel NMF Guided Level-set for DWI Prostate Segmentation

Objective: To develop an automated 3D framework for prostate segmentation from diffusion-weighted imaging (DWI). Methods: The proposed framework integrates level-set deformable model and nonnegative matrix factorization (NMF) techniques. In the proposed framework, the level-set is guided by a novel speed function that is derived using NMF, which extracts meaningful features from a large dimensional feature space. The NMF attributes are calculated using information from the DWI intensity, a probabilistic shape model, and the spatial interactions between prostate voxels. The shape model is constructed using a set of training prostate volumes and is then updated during the segmentation process using an appearance-based method that takes into account both a voxel’s location and its intensity value. The spatial interactions are modeled using a second-order pairwise 3D Markov-Gibbs random field (MGRF). Results: We tested our framework on 125 in vivo DWI-MRI prostate data sets that has been collected from 10 subjects at b-values ranging from 0 to 1000 s/mm2. Our results show that using NMF-based feature fusion to guide the level-set increases the segmentation accuracy compared with previously proposed methods using two evaluation metrics, the dice similarity coefficient (DSC) and Hausdorff distance (HD). The proposed method achieved an average DSC of 0.868 ± 0.03 and an average HD of 5.61 ± 2.12 mm compared to an average DSC of 0.83±0.07 and an average HD of 6.67 ± 1.84 mm for a maximum a posteriori (MAP)-based level-set method, and an average DSC of 0.810 ± 0.05 and an average HD of 9.07 ± 1.64 for a level-set driven only by intensity and shape information. Conclusions: Experimental results show that the integration of 3D intensity, shape, and spatial features with NMF-based feature fusion increases the ability of the proposed method to perform robust prostate segmentation despite image noise, inter-patient anatomical differences, and the similar intensities of the prostate and surrounding tissues.

Clinical application of diffusion-weighted imaging for preoperative differentiation between uterine leiomyoma and leiomyosarcoma

This study investigated the clinical usefulness of diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) value for preoperative differentiation between uterine leiomyoma and leiomyosarcoma. This study included 10 lesions from 5 patients with pelvic leiomyosarcoma and 83 leiomyoma nodules from 76 patients, as identified by postoperative pathological examination (1 autopsy). All magnetic resonance examinations were performed with a 1.5-T superconductive magnetic resonance unit. The leiomyosarcoma lesions were readily apparent via DWI, presenting as an intermediate- to high-intensity area in the uterine wall. All low-intensity areas presented as leiomyoma nodules. The mean ADC value for the 10 leiomyosarcoma lesions was 0.791 ± 0.145 (×10(-3) mm(2)/s), significantly lower than that of the leiomyoma nodules that presented with intermediate-intensity areas, 1.472 ± 0.285 (×10(-3) mm(2)/s) (n = 41) (P < .001), and high-intensity areas (1.100 ± 0.343) (n = 9) (P = .03). Additionally, in this study, the highest ADC value for a leiomyosarcoma was 1.095, with an intermediate DWI intensity. Based on these results, we classified the patients into 2 groups: low-risk group (barely any leiomyosarcoma risk) and high-risk group. Analyses comparing the 2 groups yielded the following: sensitivity, 100%; specificity, 94.0%; positive predictive value, 66.7%; negative predictive value, 100%; and accuracy, 94.6%. We suggest that this modality using a combination of signal intensity on DWI and ADC value is very effective, simple, and easy to apply clinically for differential diagnosis of leiomyosarcoma and myoma.

Characterization of ductal carcinoma in situ on diffusion weighted breast MRI

To characterize ductal carcinoma in situ (DCIS) and its subtypes on diffusion-weighted imaging (DWI). We retrospectively reviewed 74 pure DCIS lesions in 69 women who underwent DWI at 1.5 T (b = 0 and 600 s/mm(2)). Each lesion was characterized by qualitative DWI intensity, quantitative DWI lesion-to-normal contrast-to-noise ratio (CNR), and quantitative apparent diffusion coefficient (ADC). The detection rate was calculated with predetermined thresholds for each parameter. The effects of lesion size, grade, morphology, and necrosis were assessed. Ninety-six percent (71/74) of DCIS lesions demonstrated greater qualitative DWI intensity than normal breast tissue. Quantitatively, DCIS lesions demonstrated on average 56% greater signal than normal tissue (mean CNR = 1.83 ± 2.7) and lower ADC values (1.50 ± 0.28 × 10(-3) mm(2)/s) than normal tissue (2.01 ± 0.37 × 10(-3) mm(2)/s, p < 0.0001). A 91% detection rate was achieved utilizing an ADC threshold (<1.81 × 10(-3) mm(2)/s ). Non-high-grade DCIS exhibited greater qualitative DWI intensity (p = 0.02) and quantitative CNR (p = 0.01) than high-grade DCIS but no difference in ADC (p = 0.40). Lesion size, morphology, and necrosis did not affect qualitative or quantitative DWI parameters of DCIS lesions (p > 0.05). DCIS lesions have higher DWI signal intensity and lower ADC values than normal breast tissue. DWI warrants further investigation as a potential non-contrast MRI tool for early breast cancer detection.

Diffusion-weighted imaging does not predict histological grading in meningiomas

This study aims to verify the reliability of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) measurements to differentiate benign from atypical/malignant meningiomas and among different sub-types. Pre-operative DWI of 102 patients (74 females, mean age 58 years, age range 34-85 years) affected by a pathologically proven intracranial meningioma were retrospectively reviewed. DWI signal intensity of tumors was classified as hypo-, iso- or hyper-intense to grey matter. ADC values and normalised ADC(ratio) (ADC(meningioma)/ADC(normal appearing white matter)) of the neoplastic tissue (avoiding calcifications and cystic or necrotic areas) were measured by two neuroradiologists unaware of each others' reading. MRI and histological findings were compared. Meningiomas were histologically graded as malignant (1%), atypical (21.5%) and benign (77.5%). Meningothelial, transitional and fibrous were the most frequent benign sub-types (44, 16 and 10 cases, respectively). There was no statistical difference between typical and atypical/malignant meningiomas when considering mean ADC values (0.964 +/- 0.192 x 10(-3) vs 0.923 +/- 0.085 x 10(-3) cm(2)/s, p = 0.3 t-Student) or ADC(ratio) (1.266 +/- 0.290 vs 1.185 +/- 0.115, p = 0.2 t-Student). ADC values or ADC(ratio) did not differ significantly among meningioma sub-types although a nearly significant difference was found between meningothelial and transitional (post hoc analysis p = 0.06). Inter-observer agreement of ADC and ADC(ratio) measurements was high (r = 0.95 and 0.92, respectively, Pearson's linear coefficient). DWI intensity did not reach a significant correlation with meningioma's grading (p = 0.08). According to our study, DWI and ADC measurement do not seem reliable in grading meningiomas or identifying histological sub-types. Hence, these parameters should not be recommended for surgical or treatment planning.

Cerebral Sinovenous Thrombosis After Closed Head Injury

Cerebral sinovenous thrombosis (CSVT) after closed head injury is an uncommon but potentially serious complication. The aim of this study was to determine whether diffusion weighted imaging (DWI) provide predictive information regarding prognosis. We retrospectively reviewed a series of 11 patients with CSVT after closed head injury. Each patient underwent computed tomography and magnetic resonance imaging within 24 hours of onset of symptoms, including DWI, magnetic resonance venography, and conventional sequences. Apparent diffusion coefficient (ADC) values were measured in seven regions of interest in 7 of 11 patients using DWI. Follow-up imaging and clinical outcome were assessed 6 months or later after initial presentation. The most affected sinus was the posterior portion of the superior sagittal sinus. There was a mean time interval of 4.1 days between subsequent venous stroke and the initial insult. Brain edema improved in 6 of 11 patients on follow-up imaging. Six of 11 patients recovered successfully, although high or mixed DWI intensity associated with moderately decreased ADC (0.53-0.57 x 10(-3) mm2/s). Two other patients with hematomas developed venous infarction, despite mixed DWI with heterogeneous ADC value (0.55-1.11 x 10(-3) mm2/s). The other three patients, with high DWI and strongly decreased ADC values (0.26-0.27 x 10(-3) mm2/s), developed severe brain atrophy after superior sagittal sinus thrombosis. The prospective cutoff point of ADC value may be higher in CSVT after head injury with traumatic hematoma. The territory of venous infarction was found to be larger in infants after treatment failure. In infants, CSVT can demonstrate initially cytotoxic brain edema, which is reversible with anticoagulation therapy.