T2*-weighted MRI as a non-contrast-enhanced method for assessment of focal laser ablation zone extent in prostate cancer thermotherapy.

OBJECTIVES: To evaluate utility of T2*-weighted (T2*W) MRI as a tool for intra-operative identification of ablation zone extent during focal laser ablation (FLA) of prostate cancer (PCa), as compared to the current standard of contrast-enhanced T1-weighted (T1W) MRI. METHODS: Fourteen patients with biopsy-confirmed low- to intermediate-risk localized PCa received MRI-guided (1.5 T) FLA thermotherapy. Following FLA, axial multiple-TE T2*W images, diffusion-weighted images (DWI), and T2-weighted (T2W) images were acquired. Pre- and post-contrast T1W images were also acquired to assess ablation zone (n = 14) extent, as reference standard. Apparent diffusion coefficient (ADC) maps and subtracted contrast-enhanced T1W (sceT1W) images were calculated. Ablation zone regions of interest (ROIs) were outlined manually on all ablated slices. The contrast-to-noise ratio (CBR) of the ablation site ROI relative to the untreated contralateral prostate tissue was calculated on T2*W images and ADC maps and compared to that in sceT1W images. RESULTS: CBRs in ablation ROIs on T2*W images (TE = 32, 63 ms) did not differ (p = 0.33, 0.25) from those in sceT1W images. Bland-Altman plots of ROI size and CBR in ablation sites showed good agreement between T2*W (TE = 32, 63 ms) and sceT1W images, with ROI sizes on T2*W (TE = 63 ms) strongly correlated (r = 0.64, p = 0.013) and within 15% of those in sceT1W images. CONCLUSIONS: In detected ablation zone ROI size and CBR, non-contrast-enhanced T2*W MRI is comparable to contrast-enhanced T1W MRI, presenting as a potential method for intra-procedural monitoring of FLA for PCa. KEY POINTS: • T2*-weighted MR images with long TE visualize post-procedure focal laser ablation zone comparably to the contrast-enhanced T1-weighted MRI. • T2*-weighted MRI could be used as a plausible method for repeated intra-operative monitoring of thermal ablation zone in prostate cancer, avoiding potential toxicity due to heating of contrast agent.

Comparison of T2-Weighted Imaging, DWI, and Dynamic Contrast-Enhanced MRI for Calculation of Prostate Cancer Index Lesion Volume: Correlation With Whole-Mount Pathology.

OBJECTIVE: The objective of our study was to investigate the comparative effectiveness of different MRI sequences for the estimation of index lesion volume in patients with prostate cancer (PCa) compared with ground truth volume measured on whole-mount pathology. MATERIALS AND METHODS: Patients with PCa underwent multiparametric MRI (mpMRI) on a 3-T MRI scanner before radical prostatectomy. Forty PCa index lesions were identified and outlined on histology by a pathologist. Two radiologists who were informed about the presence of PCa but were not aware of lesion outlines on histology worked in consensus to delineate PCa lesions on T2-weighted imaging, apparent diffusion coefficient (ADC) maps, and early-phase dynamic contrast-enhanced MRI (DCE-MRI). The lesion volumes from different mpMRI sequences and the percentage of volume underestimation compared with pathology were calculated and correlated with volume at pathology. The repeated-measures ANOVA with the posthoc Bonferroni test was performed to evaluate whether the difference between the estimated tumor volumes was statistically significant. RESULTS: The mean PCa lesion volume estimated from pathology, T2-weighted imaging, DWI (ADC maps), and DCE-MRI were 4.61 ± 4.99 (SD) cm3, 2.03 ± 2.96 cm3, 1.81 ± 2.76 cm3, and 3.48 ± 4.06 cm3, respectively. The lesion volumes on T2-weighted images (p = 0.000002), ADC maps (p = 0.000003), and DCE-MR images (p = 0.004412) were significantly lower than those from pathology. PCa lesion volume was significantly underestimated on T2-weighted images, ADC maps, and DCE-MR images compared with pathology by 54.98% ± 22.60% (mean ± SD), 58.59% ± 18.58%, and 18.33% ± 30.11%, respectively; underestimation using T2-weighted imaging (p = 1.01 × 10-11) and DWI (p = 2.94 × 10-11) was significantly higher than underestimation using DCE-MRI. Correlations between lesion volume estimated on T2-weighted images, ADC maps, and DCE-MR images with pathology were 0.91 (p = 9.03 × 10-16), 0.86 (p = 7.32 × 10-13), and 0.93 (p = 8.22 × 10-18), respectively. CONCLUSION: DCE-MRI performed better than T2-weighted imaging and DWI for estimation of index PCa volume and therefore can be preferred over these other two sequences for volume estimation.

Development of a Rabbit Model of Radiation-Induced Sciatic Nerve Injury: In Vivo Evaluation Using T2 Relaxation Time Measurements.

OBJECTIVES: To develop a rabbit model of radiation-induced sciatic nerve injury (RISNI), using computed tomography (CT)-guided stereotactic radiosurgery, and assess the value of T2 measurements of injured nerves. MATERIALS AND METHODS: Twenty New Zealand rabbits were randomly divided into A (n = 5) and B (n = 15) groups. Group A rabbits underwent CT and magnetic resonance scan and were then killed for comparison of images and anatomy of sciatic nerves. One side of the sciatic nerve of group B rabbits received irradiation doses of 35, 50, or 70 Gy (n = 5 per group). Magnetic resonance imaging and functional assessments were performed before irradiation and 1, 2, 3, and 4 months thereafter. RESULT: The thigh section of the sciatic nerve outside the pelvis could be observed by CT and magnetic resonance imaging. T2 values of the irradiated nerve of the 35-Gy group increased gradually, peaking at 4 months; T2 values of the 50-Gy group increased faster, peaking at 3 months. Significant differences between the 35-Gy and control groups were found at 3 and 4 months, and between the 50-Gy and control groups at 2, 3, and 4 months. Functional scores of the 50-Gy group declined progressively, whereas the 35-Gy group scores reached a low point at 3 months posttreatment and then recovered. Functional scores of the irradiated limbs demonstrated a negative correlation with T2 values (r = -0.591 and -0.595, P < 0.05). Electron microscopy revealed progressive deformation and degeneration of the irradiated nerve in the 35- and 50-Gy groups, which were more severe in the 50-Gy group. CONCLUSIONS: A rabbit RISNI model can be produced using the midthigh segment of the sciatic nerve and single-fraction doses of 35 and 50 Gy. Although T2 values are useful for monitoring RISNI, they may not be sensitive enough to evaluate its severity.

In vivo evaluation of sciatic nerve crush injury using diffusion tensor imaging: correlation with nerve function and histology.

OBJECTIVE: The aim of this study was to prospectively estimate magnetic resonance diffusion tensor imaging parameters in distal portions of crushed sciatic nerves in rabbits and correlation with neurological function and histology. METHODS: Thirty-two rabbits were randomly divided into 8 groups and followed up at 10 weeks. The right sciatic nerves were crushed, and the left sciatic nerves served as the control group with sham operation. Another 4 rabbits were chosen in the normal control group. Diffusion tensor imaging scan was obtained on bilateral sciatic nerves using spin-echo single-shot echo planar imaging. The values of fractional anisotropy (FA), apparent diffusion coefficient, and eigenvalue (λ║ and λ⊥) were measured on diffusion tensor imaging. Quantitative assessment of functional recovery in crushed nerves included toe-spreading reflex and modified Tarlov score, as well as pathology of the injured nerves. RESULTS: Fractional anisotropy of distal portions in injured nerves reduced slightly on the first day and dropped to the minimum at the fourth day after surgery. Then, FA increased gradually from the eighth day to the eighth week. After that, FA recovered nearly normal in the 10th week after injury. There was statistical significance in FA during 4 days to the eighth week and λ⊥ values between distal portions of injured nerves and normal control nerves (P < 0.05). Fractional anisotropy of distal portions to injured nerves correlated significantly with the nerve function score(r = 0.898, P < 0.01), whereas λ⊥ of distal portions of injured nerves demonstrated negative correlation with the nerve function score(r = -0.820, <0.01). Fractional anisotropy values of distal portions of injured nerves formed a similar time course as functional recovery, whereas λ⊥ indicated a opposite trend. CONCLUSIONS: The changes in FA and λ⊥ of distal portions of injured sciatic nerves correlate well with functional recovery and histology. Therefore, FA and λ⊥ of distal portions of injured sciatic nerves can be used as a marker to monitor Wallerian degeneration and regeneration of crushed sciatic nerves.

Primitive neuroectodermal tumor arising in the abdominopelvic region: CT features and pathology characteristics.

BACKGROUND: We analyze the computed tomography (CT) findings of a peripheral primitive neuroectodermal tumor (pPNET) arising in the abdominopelvic cavity and to improve understanding of the CT images of the tumor. MATERIALS AND METHODS: Twelve cases of pPNET confirmed by histopathology were analyzed retrospectively. Image characteristics of CT scanning were analyzed and compared with the pathology of the tumors. RESULTS: There were 8 males and 4 females with mean age of 34.5 years. Unenhanced CT images showed large heterogeneous and ill-defined or well-defined masses with multiple patchy hypodense areas. The average diameter was 9.8 cm (range 4.0-17.2 cm). Contrast-enhanced CT images showed variable heterogeneous contrast enhancement with multiple non-enhancement areas. 3 cases revealed metastasis and 4 cases invaded into adjacent organs. Pathology showed areas of degeneration and necrosis in all tumors. Cluster of differentiation 99 and neurone specific enolase were detected positive in 11 and 12 cases, respectively. CONCLUSIONS: In conclusion, pPNET in the abdominopelvic cavity likely affects young adults with a slight male preponderance and tend to be large and aggressive. Although CT findings are nonspecific and variable, a large ill-defined or well-defined heterogeneous mass with multiple patchy hypodense areas reflecting their cystic degeneration and necrosis on pathology examination may suggest the diagnosis of pPNET.

Non-HIV talaromycosis: Radiological and clinical analysis.

To investigate the characteristics of spiral computed tomography (CT), positron emission tomography-computed tomography (PET/CT) and clinical manifestations of talaromycosis to improve the diagnostic level and deepen its recognition in radiology.Radiological, clinical, and pathological manifestations of 15 patients of non-HIV talaromycosis confirmed by bronchofiberscope lung biopsy and/or abscess puncture fluid culture and/or blood culture and/or sputum culture were analyzed retrospectively. All patients underwent chest CT, among them, six had a brain MRI, and six had a PET/CT scan before treatment.On plain CT scan, there were multiple patches and massive consolidation in 6 patients, multiple patchy consolidations and patchy ground-glass opacities in 3 patients, solitary or multiple nodules and masses in 3 patients, multiple cavities and small nodules in 3 patients. Multiple lymphadenectasis appeared in bilateral hila, mediastinum, and neck in 10 patients. In contrast CT scan, the parenchyma of the lesions had a slight enhancement in 10 patients, moderate enhancement in 3 patients, obvious enhancement in 2 patients. Seven cases had bone destruction and hyperplasia, cranial involvement in 1 patient and liver involvement in 3 patients, respectively. On PET/CT, five patients showed elevated standard uptake value (SUV).The radiological manifestations of non-HIV talaromycosis show multiple consolidations, ground-glass opacities, multiple nodules or masses in bilateral lungs, deep-seated enlarged lymph nodes and bone destruction in multiple systems. The final diagnosis should be based on the culture of talaromycosis.

Effect of Echo Times on Prostate Cancer Detection on T2-Weighted Images.

PURPOSE: To compare the effect of different echo times (TE) on the detection of prostate cancer (PCa) on T2-weighted MR images. MATERIALS AND METHODS: This study recruited patients (n = 38) with histologically confirmed PCa who underwent preoperative 3T MRI. Three radiologists independently marked region on interests (ROIs) on suspected PCa lesions on T2-weighted images at different TEs: 90, 150, and 180 ms obtained with Turbo Spin Echo imaging protocol with multiple echoes. The ROIs were assigned a value 1-5 indicating the reviewer's confidence in accurately detecting PCa. These ROIs were compared to histologically confirmed PCa (n = 95) on whole mount prostatectomy sections to calculate sensitivity, positive predictive value (PPV), and confidence score. RESULTS: Two radiologists (R1, R2) showed significantly increased sensitivity for PCa detection at 180 ms TE compared to 90 ms (R1: 43.2, 50.5, 50.5%, R2: 45.3, 44.2, 53.7% at TE of 90, 150, 180 ms, respectively) (p = 0.048, 0.033 for R1 and R2). Sensitivity was similar for radiologist 3 (45.3%-46.3%) at different TE values (p = 0.953). No significant difference in the PPV (R1: 64.1%-70.6%, R2: 46.7%-56.0%, R3: 70.5%-81.5%) and the confidence score assigned (R1: 4.6-4.8, R2: 4.6-4.8 R3: 4.3-4.4) was found for either of the radiologists. CONCLUSION: Our results suggest improved detection of PCa with similar PPV and confidence scores when higher TE values are utilized for T2-weighted image acquisition.

Imaging of olfactory bulb and gray matter volumes in brain areas associated with olfactory function in patients with Parkinson's disease and multiple system atrophy.

UNLABELLED: We explored if magnetic resonance imaging sequences might aid in the clinical differential diagnosis of idiopathic Parkinson's disease (IPD) and multiple system atrophy (MSA). We measured the volumes of the olfactory bulb, the olfactory tract, and olfaction-associated cortical gray matter in 20 IPD patients, 14 MSA patients, and 12 normal subjects, using high-resolution magnetic resonance imaging sequences in combination with voxel-based statistical analysis. We found that, compared to normal subjects and MSA patients, the volumes of the olfactory bulb and tract were significantly reduced in IPD patients. The gray matter volume of IPD patients decreased in the following order: the olfactory area to the right of the piriform cortex, the right amygdala, the left entorhinal cortex, and the left occipital lobe. Further, the total olfactory bulb volume of IPD patients was associated with the duration of disease. The entorhinal cortical gray matter volume was negatively associated with the UPDRS III score. CONCLUSION: Structural volumes measured by high-resolution magnetic resonance imaging may potentially be used for differential diagnosis of IPD from MSA.

Choroid plexus tumours: classification, MR imaging findings and pathological correlation.

INTRODUCTION: Choroid plexus tumours (CPTs) are extremely rare intraventricular neoplasms and are prone to bleeding during surgery. The purpose of this study was to summarise the MR imaging characteristics of 13 CPT cases. METHODS: Magnetic resonance images of 13 patients (six men and seven women; mean age 21.1 years) with pathologically proved CPTs were retrospectively reviewed. MR findings of the tumours were evaluated, with emphasis on their location, size, shape, internal architecture, margin and pattern and degree of enhancement. Differences in signal intensity characteristics were also investigated on MR images and analysed according to histological subtypes. RESULTS: Lesions were in the lateral ventricles (n = 7), fourth ventricle (n = 5) and cisterna magna (n = 1), with a mean size of 5.0 cm (range 2.0-7.9 cm). The tumour parenchyma was a mixture of nodular or patchy areas of inhomogeneous isointense to slightly hyperintense signal on T2-weighted images. On postcontrast MR images, all lesions, except for one, had moderate to marked contrast enhancement. Multiple tortuous areas of 'flow void' signal extended through all the tumours except for two. A thin capsule could be seen in six cases. CONCLUSION: Observation of large intraventricular tumours with inhomogeneity on T2-weighted images and flow void is suggestive of CPTs. Checking for signs of a thin capsule, extensive peritumoural oedema and necrosis may be useful when classifying CPTs.

Mucoepidermoid carcinoma of the lung: common findings and unusual appearances on CT.

OBJECTIVES: This study aimed to analyze the computed tomographic (CT) various findings of mucoepidermoid carcinoma of the lung and to improve the diagnostic efficacy for such tumor. MATERIALS AND METHODS: Sixteen consecutive patients with mucoepidermoid carcinoma of the lung confirmed by pathology were reviewed retrospectively. All the patients had undergone unenhanced and contrast-enhanced examinations; one of them also had undergone 18F-FDG PET/CT examinations. RESULTS: There were 6 males and 10 females with a mean age of 34.1 years. On CT plain scan, 14 out of 16 cases showed a well-defined endobronchus mass (n=12) or single peripheral nodule (n=2) with obstructive pneumonia or atelectasis (n=4), one case appeared a cavity in the tumor mass, and one presented diffuse circumferential wall thickening. Punctate calcification was observed in four cases (25%). Tumors showed mild (n=4, 25 %), moderate (n=6, 37.5%), and marked (n=6, 37.5%) degrees of contrast enhancement. Two patients had mediastinal lymph node metastasis, and one of them also had bone metastasis. CONCLUSIONS: Mucoepidermoid carcinoma of the lung likely affects young adults. The common findings included a well-defined ovoid or rounded intraluminal mass; and uncommon findings included cavitation, diffuse thickening, or spiculation. Although CT manifestations of it are variable and nonspecific, a well-defined ovoid or lobulated intraluminal or lung peripheral mass with moderate to marked heterogeneous contrast enhancement may suggest the diagnosis of mucoepidermoid carcinoma of the lung. It should be included in the differential diagnosis of regional tumors.

[MRI findings of uterine cervical cancer and value of MRI in preoperative staging].

OBJECTIVE: To evaluate the value of magnetic resonance imaging (MRI) in diagnosis and preoperative staging of uterine cervical cancer. METHODS: MRI findings and staging in 72 patients with cervical carcinoma were retrospectively analyzed, and the size, location, signal intensity and invasion of the tumor were observed. MRI sequence included SE T1WI, (TSE)T2WI, T2WI/SPIR and contrast-enhanced T1WI. RESULTS: MRI identified uterus cervical cancer in all cases with the exception of only 1 case of IA stage. The tumor was represented by hypointensity and isointensity on T1WI, heterogeneous and homogeneous hyperintensity on T2WI, mildly heterogeneous enhancement after bolus intravenous GD-DTPA injection. MRI had an accuracy of 86% in localization of the tumor, but its accuracy in clinical staging was only 64% (chi2=6.453, P<0.05). The tumor volume measured by MRI was similar with that by pathological measurement (1.94-/+1.15 vs 1.94-/+1.11, P>0.05). CONCLUSION: MRI can accurately describe the size and invasion of uterine cervical cancer, especially useful in detecting parametrial invasion, but for diagnosis of IA uterine cervical cancer, MRI findings are not sufficient without considerations of clinical findings and cellular examination.