H proton MR spectroscopy and diffusion-weighted imaging in discrimination between pyogenic brain abscesses and necrotic brain tumors

Background

Differentiation between cerebral abscesses and necrotic brain tumors showing ring enhancement can be confusing at times by conventional MRI. The introduction of advanced imaging techniques, such as MR spectroscopy and diffusion WI, have contributed to the differentiation.The purpose of this study is to test the hypothesis that MR spectroscopy and diffusion weighted can be used to differentiate between necrotizing or cystic brain tumor and brain abscesses.

Methods

The study was conducted on 45 patients (necrotic or cystic tumor (30 cases); brain abscess (15 cases) showing ring-shaped contrast enhancement on conventional MRI. 1.5-T ¹H-MR Spectroscopy and diffusion WI were performed and the results were ensured by stereotactic biopsy or aspiration procedures in surgically indicated cases and/or follow up.

Results

14 patients (out of 15) with pyogenic abscess had lactate, amino acids, and acetate peaks; Succinate peak is seen as extra peak in three of these patients, and lipid peaks are also seen as extra peaks in 3 patients. One patient with brain stem abscess after 20 days treatment by antibiotics shows only lactate and lipid peaks. 2 of them show mild increase in choline with decrease in NAA (brain tissue contamination).17 out of 30 patients with cystic or necrotic tumor showed only lactate peak in MRS. While 13 patients show lactate and lipid peaks, four of them show additional high choline peak with low NAA and creatine peak (contamination with brain tissue).The results were confirmed by Sterotactic biopsy in 27 cases and aspiration in 13 cases and follow up for all cases.The sensitivity, specificity, PPV, NPV and overall accuracy of diffusion and MRS were 88%, 100%, 100%, 93.3% and 95.5% respectively.

Conclusion

¹H-MRS and diffusion WI are fast, easy to perform, noninvasive, and provide additional information that can accurately differentiate between necrotic/cystic tumors and cerebral abscesses.     

Role of diffusion MRI and proton magnetic resonance spectroscopy in characterization of ovarian neoplasms

Introduction

Adnexal masses are a common clinical problem and considered as the leading indication for gynecological surgery. The ovary and adnexal structures are relatively difficult to image with any technology. Magnetic resonance spectroscopy (MRS) can detect metabolic changes. As molecular changes often precede morphologic alterations, sensitivity is expected to improve by MRS. Diffusion weighted magnetic resonance imaging (DW-MRI) is sensitive to molecular diffusion which is due to random microscopic translational motion of molecules (known as Brownian motion). In the event of morphologic evaluation of cystic ovarian tumors, whether benign or malignant, DW-MR imaging and calculated apparent diffusion coefficient (ADC) values would be useful for evaluation.

Purpose

The aim of this study is to evaluate the role of diffusion MRI & proton magnetic resonance spectroscopy (H-MRS) in diagnosis of ovarian neoplasms.

Subjects and methods

This study included 20 patients, their ages ranged from 20 to 72 years. In all cases, diagnosis was proven by surgical and pathological examination. Trans-abdominal ultrasound (n = 20) and trans-vaginal ultrasound (n = 11) were included in our routine protocol to obtain baseline information preceding MR examination. The routine MR examination protocol included: T1WI, T2WI, and post contrast fat suppressed T1WI. Diffusion weighted imaging (DWI) was done to all patients at b0, b500, b1000 and ADC values were calculated. MRS was performed in all cases using multi-voxel point resolved surface coil spectroscopy (PRESS sequence) for volume localization.

Results

Fourteen cases (70%) had benign ovarian masses while the remaining six cases (30%) had malignant masses. High lipid peak was detected in all three cases of mature cystic teratoma. All cases of simple serous cysts showed choline and creatine signals that were higher than the average noise level but lower than the two fold higher noise level. Sharp choline peak was detected in all malignant ovarian masses (except a case of metastases under chemotherapy) as well as the case of fibroma. Creatine signal was detected in all benign and malignant masses except two cases of mature cystic teratoma and cases of endometrioma. Lactate signal was detected only in cases of hemorrhagic cysts, mature cyst teratoma and one case of endometrioma and not obtained in any of malignant lesions except dysgerminoma. High NAA signal was detected in dysgerminoma and all three cases of mature cystic teratomas. The mean Cho/Cr ratio was significantly higher in malignant than benign ovarian masses (<0.05), there was no significant difference in mean and lowest ADC values between malignant and benign lesions.

Conclusion

Proton MRS using Cho/Cr ratio added useful information for the diagnosis of different ovarian neoplasms. Direct visual assessment of DWI of ovarian lesions is not useful in differentiating benign from malignant ovarian lesions; determining the threshold of the ADC for diagnosing cystic ovarian tumors is difficult because of their large variance. Further experience with a larger and more biologically variable range of tumors is recommended.     

Renal masses measuring under 2 cm: Pathologic outcomes and associations with MRI features

Purpose

To evaluate pathologic outcomes and associations with MRI features in small renal masses measuring up to 20 mm

Methods

86 patients (61 ± 13 years; 45 M/41F) with 92 renal masses measuring up to 20 mm that underwent MRI prior to tissue diagnosis were included. Two radiologists independently evaluated all masses for microscopic lipid, hemorrhage, T2-hyperintensity, T2-homogeneity, cystic/necrotic areas, hypervascularity, enhancement homogeneity, circumscribed margins, and predominantly exophytic location. These MRI features, as well as patient age, gender, and history of RCC, were compared with pathologic findings using Fisher's exact test, unpaired t-test, and multivariate logistic regression.

Results

26.1% (24/92) of masses under 2 cm were benign, only 32.6% (30/92) were clear-cell RCC, and only 7.6% (7/92) were high-grade. Among 16 masses measuring up to 1 cm, only 12.5% (2/16) were clear-cell RCC, and none was high-grade. Within the entire cohort, no MRI or clinical feature showed a significant difference between benign and malignant lesions (p ≥ 0.053). However, for both readers, clear-cell RCC exhibited a significantly higher frequency of T2-hyperintensity, cystic/necrotic areas, and hypervascularity, and a significantly lower frequency of hemorrhage, T2-homogeneity, and enhancement homogeneity (p < 0.001–0.036). Hypervascularity was a significant independent predictor of clear-cell RCC for both readers (p = 0.002–0.007), as was T2-hyperintensity for reader 2 (p = 0.007).

Conclusion

A substantial fraction of small renal masses were benign, and when malignant, largely exhibited indolent pathologic characteristics, particularly when measuring under 1 cm Although small benign and malignant masses could not be differentiated on MRI, hypervascularity showed a significant independent association with clear-cell RCC in comparison with other lesions.     

Paradoxical signal pattern of mediastinal cysts on T2-weighted MR imaging: phantom and clinical study

Purpose

To evaluate the intracystic MRI (magnetic resonance imaging) signal intensity of mediastinal cystic masses on T2-weighted images.

Materials and methods

A phantom study was performed to evaluate the signal intensity of a mediastinal cystic mass phantom (rubber balloon containing water) adjacent to a cardiac phantom pulsing at the rate of 60/min. T2-weighted images (sequence, fast spin echo [FSE] and single shot fast spin echo [SSFSE]) were acquired for the mediastinal cystic mass phantom. Further, a clinical study was performed in 33 patients (16 men, 17 women; age range, 19-85 years; mean, 65years) with thymic cysts or pericardial cysts. In all patients, T2-weighted images (FSE and SSFSE) were acquired. The signal intensity of cystic lesion was evaluated and was compared with that of muscle. A region of interest (ROI) was positioned on the standard MR console, and signal intensity of the cystic mass (cSI), that of the muscle (mSI), and the rate of absolute value of cSI–mSI to standard deviation (SD) of background noise (|cSI–mSI|/SD = CNR [contrast-to-noise ratio]) were measured.

Results

The phantom study demonstrated that the rate phantom-ROI/saline-ROI was higher in SSFSE (0.36) than in FSE (0.19). In clinical cases, the degree of the signal intensity was higher in SSFSE than in FSE. The CNR was significantly higher in SSFSE (mean ± standard deviation, 111.0 ± 47.6) than in FSE (72.8 ± 36.6) (p < 0.001, Wilcoxon signed-rank test).

Conclusions

Anterior mediastinal cysts often show lower signal intensity than the original signal intensity of water on T2-weighted images. SSFSE sequence reduces this paradoxical signal pattern on T2-weighted images, which may otherwise cause misinterpretation when assessing cystic lesions.     

Role of dynamic contrast-enhanced and diffusion weighted MRI in evaluation of necrosis of hepatocellular carcinoma after chemoembolization

Purpose

The purpose of this study is to evaluate the role of dynamic contrast enhanced and diffusion weighted MRI in the assessment of response and necrosis in the treatment of hepatocelluar carcinoma after transcatheter arterial chemoembolization (TACE).

Subjects and methods

Precontrast T1, T2, STIR, Dynamic contrast enhanced and respiratory triggered diffusion weighted MR images (b factor, 500, 1000 s/mm² obtained in 50 patients with hepatocellular carcinoma who underwent transarterial hepatic chemoembolization). Diffusion-weighted MR images, gadolinium-enhanced MR images after TACE were assigned confidence levels for postoperative HCC recurrence. The sensitivity, specificity, PPV, NPV and overall agreement were calculated for both the dynamic and the DWI images. Apparent diffusion coefficients (ADCs) were calculated searching for a cut off value using the ROC curve.

Results

Dynamic MRI had a sensitivity of 90.5%, a specificity of 96.6%, a positive predictive value of 95%, a negative predictive value of 93.3% and an overall agreement of 94% compared to 100%, 65.5%, 67.7%, 100% and 80% respectively of diffusion weighted imaging.The difference between the malignant and benign groups’ ADC variables was statistically significant P value 0.006.The ROC curve showed that the area under the curve is C = 0.728 with SE = 0.075 and 95% CI from 0.582 to 0.874.

Conclusion

Diffusion weighted MR imaging has lower specificity compared to dynamic MRI with increased false positives. We suggest that increase is due to intralesional hemorrhage or liquefactive necrosis causing diffusion restriction. Diffusion weighted imaging may act as a supplementary sequence to compensate the dynamic MRI in patients who could not hold their breath adequately.     

Diffusion tensor tractography as a supplementary tool to conventional MRI for evaluating patients with myelopathy

Purpose

The aim of this study was to assess the clinical utility of DTI including apparent diffusion coefficient (ADC), fractional anisotropy (FA), in patients with symptoms of spinal cord myelopathy.

Patients and methods

Fifteen subjects with clinical symptoms of acute (n = 3) or slowly progressive (n = 12) spinal cord myelopathy and 11 healthy volunteers were prospectively selected. They all underwent magnetic resonance imaging of the spine at 3.0 T machine. In addition to conventional MRI, DTI was performed; maps of the apparent diffusion coefficient and of fractional anisotropy were reconstructed. Diffusion tensor tractography was used to visualize the morphological features of normal and impaired white matter at the level of the pathological lesions in the spinal cord. The patients were divided into two groups according to the signal intensity on T2WI (group A with no change in signal intensity and group B with high signal intensity).

Results

There were no statistically significant differences in the apparent diffusion coefficient and fractional anisotropy values between the different spinal cord segments of the normal subjects. All of the patients in group B had increased apparent diffusion coefficient values and decreased fractional anisotropy values at the lesion level compared to the normal controls. However, there were no statistically significant diffusion index differences between group A patients and the normal controls.

Conclusion

Diffusion tensor imaging is a reliable method for the evaluation of the diffusion properties of normal and compressed spinal cords. Furthermore, this technique can be used as an important supplementary tool to conventional MRI for the quantification of fiber damage in spinal cord compression, thus has the potential to be of great utility for treatment planning and follow up.     

Proton MR spectroscopy in patients with pyogenic brain abscess: MR spectroscopic imaging versus single-voxel spectroscopy

Purpose

Single-voxel spectroscopy (SVS) has been the gold standard technique to diagnose the pyogenic abssess. Two-dimensional magnetic resonance spectroscopic imaging (MRSI) is able to provide spatial distribution of metabolic concentration, and is potentially more suitable for differential diagnosis between abscess and necrotic tumors. Therefore, the purpose of this study was to evaluate the equivalence of MRSI and SVS in the detection of the metabolites in pyogenic brain abscesses.

Materials and methods

Forty-two patients with pyogenic abscesses were studied by using both SVS and MRSI methods. Two neuroradiologists reviewed the MRS data independently. A κ value was calculated to express inter-reader agreement of the abscesses metabolites, and a correlation coefficient was calculated to show the similarity of two spectra. After consensus judgment of two readers, the binary value of metabolites of pyogenic abscesses (presence or absence) was compared between SVS and MRSI.

Results

The consistency of spectral interpretation of the two readers was very good (κ ranged from 0.95 to 1), and the similarity of two spectra was also very high (cc = 0.9 ± 0.05). After consensus judgment of two readers, the sensitivities of MRSI ranged from 91% (acetate) to 100% (amino acids, succinate, lactate, lipid), and the specificities of MRSI were 100% for detecting all metabolites with SVS as reference.

Conclusion

SVS and MRSI provide similar metabolites in the cavity of pyogenic brain abscess. With additional metabolic information of cavity wall and contralateral normal-appearing brain tissue, MRSI would be a more suitable technique to differentiate abscesses from necrotic tumors.     

Radiological and clinicopathological features of pPNET

Purpose

To analyze the radiological and clinicopathological features of peripheral primitive neuroectodermal tumor (pPNET).

Materials and methods

We retrospectively reviewed the computed tomography (CT) and magnetic resonance (MR) imaging of 14 cases of pPNET confirmed immunohistochemically. Relevant clinical data was also obtained.

Results

Of 14 cases, there were 10 male and 4 female with a mean age of 28 years. The main symptoms were the aggravated pain of the lesion site and enlarged palpable masses. Fourteen lesions were located in the chest wall (n = 4), retroperitoneum (n = 3), pelvic cavity (n = 2), intraspinal area (n = 2), nasal cavity (n = 1), leg (n = 1) and iliac bone (n = 1). Eleven lesions originating from the soft tissue mainly demonstrated large and infiltrative mass with (n = 4) or without (n = 7) bony invasion. Ten cases of them showed heterogeneous density with patchy, necrotic foci and moderate heterogeneous enhancement. Four of them with large cystic area contained irregular septations within them. Two intraspinal cases had extradural lesions, extending through the intervertebral foramen and formed paraspinal soft tissue masses with vertebral destruction. The case within iliac bone demonstrated extensive mixed (lytic/osteoblastic) lesion with large adjacent soft tissue mass. After surgery or therapy, 10 patients died of local recurrences or metastases.

Conclusion

The diagnosis of pPNET should be suggested in young patient when imaging depicts a large, ill-defined, soft-tissue mass containing area of cystic degeneration with internal septations and extending along the neural route and nearby the middle of the trunk. The key for correct diagnosis is to inosculate imaging to clinical data.     

Magnetic resonance imaging versus Ultrasound examination in detection of prenatal fetal brain anomalies

Purpose

Evaluation of the role of MR Imaging in detection of fetal brain anomalies versus 2D and 4D Ultrasound examination.

Study design

This study included 23 pregnant females who were suspected to have fetus with congenital brain anomalies over a period of one year using ultrasound. MRI was done within one week following 2D and 4D US examination. The maternal age ranged from 18 to 39 years. The gestational age ranged from 16 to 36 weeks (mean age = 26 weeks). Antenatal Ultrasound and magnetic resonance findings were compared with postnatal MRI findings.

Results

We reported different types of congenital brain anomalies including eight cases of isolated central nervous system anomalies. MRI and ultrasound showed concordant findings in six cases. MRI changed the diagnosis in 14 cases and provided additional information in two cases. Ultrasound was superior to magnetic resonance imaging in one case at second trimester due to fetal motion.

Conclusion

Our results showed that fetal MR imaging is useful in detection of fetal central nervous system anomalies as well as a complementary modality to 2D/4D Ultrasound in diagnosis of fetal central nervous system anomalies.     

Diagnostic yield of combined magnetic resonance spectroscopy and diffusion weighted imaging in intracranial neoplasms

Purpose

Our intention was to evaluate the role of combined diffusion magnetic resonance imaging and spectroscopy in diagnosis and grading of brain tumors.

Materials and methods

Ninety-three included cases underwent magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) of the brain lesion, stereotactic or open biopsies and histopathological examination. MRI protocol included DWI and calculated ADC values. Multivoxel MRS spectroscopic technique (MVS) was used and all MRS metabolic parameters were obtained.

Results

High grade tumors had significantly lower ADC values than low grade tumors (P < 0.001). ADC values were the lowest in lymphoma (0.54 × 10⁻³ mm²/s) and the highest in craniopharyngioma (1.9 × 10⁻³ mm²/s). MRS revealed a statistically significant difference in CHO/NAA and CHO/Cr ratios between low and high grade tumors with P < 0.01 and P < 0.001, respectively. The mI/Cr ratio and presence of lactate, lipid and taurine also aided in differentiation and grading of brain tumors. The overall MRI/MRS sensitivity and specificity were 91%, 90.5%, respectively.

Conclusion

MRS has a robust diagnostic accuracy in cases of well defined high or low grade brain neoplasms. ADC value had the ability to confirm and differentiate low from high grade tumors in many situations where there were diagnostic confusions with MRS due to borderline values.     

Brain magnetic resonance imaging findings in cryptogenic stroke patients under 60 years with patent foramen ovale

Purpose

To compare magnetic resonance imaging (MRI) brain feature in cryptogenic stroke patients with patent foramen ovale (PFO), cryptogenic stroke patients without PFO and patients with cardioembolic stroke.

Materials and methods

The ethics committee required neither institutional review board approval nor informed patient consent for retrospective analyses of the patients’ medical records and imaging data. The patients’ medical files were retrospectively reviewed in accordance with human subject research protocols. Ninety-two patients under 60 years of age were included: 15 with cardioembolic stroke, 32 with cryptogenic stroke with PFO and 45 with cryptogenic stroke without PFO. Diffusion-weighted imaging of brain MRI was performed by a radiologist blinded to clinical data. Univariate, Fischer's exact test for qualitative data and non-parametric Wilcoxon test for quantitative data were used.

Results

There was no statistically significant difference found between MRI features of patients with PFO and those with cardioembolic stroke (p < .05). Patients without PFO present more corticosubcortical single lesions (p < .05) than patients with PFO. Patients with PFO have more often subcortical single lesions larger than 15 mm, involvement of posterior cerebral arterial territory and intracranial occlusion (p < .05) than patients with cryptogenic stroke without PFO.

Conclusion

Our study suggests a cardioembolic mechanism in ischemic stroke with PFO.     

The role of apparent diffusion coefficient (ADC) value in the differentiation between the most common pediatric posterior fossa tumors

Background

Diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) map provide information on MRI about the cellularity of the tumor and have an important role in the pre-operative differentiation of different tumor types.

Aim

Is to evaluate the role of ADC value measurement in the differentiation between the most common pediatric posterior fossa tumors which include juvenile pilocytic astrocytoma, ependymoma and medulloblastoma.

Patients & methods

Thirty patients were retrospectively included in this study. They were referred from the Neurosurgery Department and all of them suspected to have posterior fossa SOL according to the contrast enhanced CT. All patients were subjected to conventional MRI followed by diffusion MR imaging and calculation of the ADC values.

Results

In JPA (group 1, n = 14), ADC values ranged between 2.4 and 1.3 × 10⁻³ mm²/s, ependymoma (group 2, n = 9), ADC values ranged between 1 and 1.3 × 10⁻³ mm²/s and medulloblastoma (group 3, n = 7), ADC values ranged between 0.5 and 0.9 × 10⁻³ mm²/s. Statistically significant difference in ADC value was detected between group1, group 2 and group 3, while no statistically significant difference was detected between group 1 and group 2.

Conclusion

The calculation of ADC value in the solid enhancing portion of a tumor is a simple and reliable technique for preoperative differentiation of the most common posterior fossa.     

Role of diffusion weighted imaging and proton magnetic resonance spectroscopy in ring enhancing brain lesions

Aim of the work

To assess and compare the usefulness and efficacy of both diffusion weighted imaging (DWI) and proton magnetic resonance spectroscopy (¹HMRS) in brain lesions with ring enhancement in post contrast T1WI and to determine which method is more effective.

Subjects and methods

Thirty patients with ring-enhanced brain lesions were classified into 2 groups, abscess group (11 patients) and tumor group (19 patients), were examined using diffusion-weighted imaging (DWI) and H-proton magnetic resonance spectroscopy (¹HMRS).

Results

Restricted diffusion and low ADC value were seen in 9 (81%) patients of brain abscesses, however, free diffusion and high ADC value were found in 18 (94%) patients with necrotic brain tumor. The abscess group showed aminoacids, acetate and lactate in 9 patients and extra peak of succinate was found in 1 patient; however in the tumor group lactate alone was found in 12 patients, lactate and choline were seen in 5 patients, none of the patients showed amino acids, succinate or acetate.

Conclusion

Both DWI and ¹HMRS are useful and efficient imaging techniques in ring enhancing brain lesions and differentiate between pyogenic brain abscesses and necrotic tumors, but DWI is accurate, has less imaging time than ¹HMRS, also is available in many imaging centers.     

The value of b0 images obtained from diffusion-weighted echo planar sequences for the detection of intracranial hemorrhage compared with GRE sequence

Purpose

Our aim was to evaluate the clinical utility of b0EPI images obtained from diffusion sequence for the detection of the intracranial hemorrhagic lesions, especially acute intracerebral bleeds thereby shorten the scan time particularly in the critical acute cases of stroke.

Materials and methods

Among all consecutive MR brain studies performed in our department last year, we retrospectively selected those who followed the following criteria: (1) clinically suspected or radiographically confirmed acute infarction or hemorrhage. (2) MRI imaging including DWI and T2∗ images. Sensitivity of hemorrhage detection, conspicuity of lesions, and diagnostic certainty were compared between the b0EPI and GRE sequences.

Results

There were 77 hemorrhagic lesions with a variety of pathogeneses in various locations. 76/77 (98.7%) of these lesions were hemorrhagic (hypointense) on the GRE sequences, whereas 61 (79.2%) were characterized as hemorrhagic on b0EPI images, and 16 (20.8%) were not detected. The overall difference in hemorrhage conspicuity/diagnostic certainty between GRE and b0EPI sequences was statistically significant (P < .05).

Conclusion

b0EPI sequence, although shorter in acquisition time, was inferior to GRE imaging in the detection of acute and chronic intracerebral hemorrhage.     

Magnetic Resonance Imaging Evaluation of Perianal Fistulas

Purpose

The purpose of this study was to discuss the usefulness of magnetic resonance imaging in evaluating perianal fistulas, their ramifications, extent, associated abscesses and relations with the anal sphincter complex and its role in preoperative classification.

Material & methods

A retrospective study was carried out using picture archiving and communication system. Data of 58 patients presented with a clinical suspicious of perianal fistula from April 2012 to March 2013 was collected. In all patients pre contrast T2 propeller with and without fat suppression, diffusion weighted and pre and post contrast liver acceleration volume acquisition sequences were obtained. Pulse sequences were as follows: T2 propeller (TR: 7766 ms, TE: 122 ms), Diffusion weighted (TR: 7000 ms, TE: 67 ms), LAVA (TR: 7 ms, TE: 3.242 ms).

Results

MRI revealed a total number of 38 fistulae in 35 (60%) patients while 13 (22%) patients had only perianal sinuses. Out of these 35 patients, 4 were females and 31 were male subjects. Out of total 38 fistulae seen in these 35 patients, 11 (29%) were transsphincteric, 24 (63%) were intersphincteric and 2 (5%) were suprasphincteric. Only 1 (3%) case was extrasphincteric fistula. Twenty-six fistulae (68%) were simple, whereas 12 (32%) showed associated abscess formation, inflammation and branching course.

Conclusion

Our results support that MRI is the method of choice for evaluating perianal fistulae as they display the anatomy of the sphincter muscles orthogonally with a background of good contrast resolution. Moreover, with MRI we can accurately classify perianal fistulas preoperatively along with the detection of associated infection and help in planning a successful surgery.     

Role of computed tomography and magnetic resonance imaging in diagnosing pericardial lesions

Objective

In this research, patients who had pericardial lesions are imaged by either CT or MRI and the purpose of this paper is to discuss which imaging modality should be used in the assessment of patients with different pericardial diseases.

Patients and methods

Thirty patients ranging in age between 3 months and 46 years diagnosed as having pericardial lesions by transthoracic echocardiography were prospectively studied. All patients were examined by history taking, chest X-ray, clinical examination, transthoracic echocardiography, Multidetector CT and/or magnetic resonance imaging.

Result

Several types of lesions were identified including constrictive pericarditis (n = 10), pericardial simple effusion (n = 9), pericardial tumors (n = 5), pericardial abscess (n = 4), pericardial hemorrhage (n = 4) and one case of pericardial cyst. Three patients had combined lesions.

Conclusion

CT and MR imaging should be used when findings at echocardiography are difficult to interpret, inconclusive or conflict with clinical findings. CT is better used for the assessment of postoperative cases while MRI is superior in detecting and diagnosing pericardiac masses and constrictive pericarditis.Also, because of radiation involving CT scan should be avoided in children if possible but has the advantage of fast imaging speed and often no need for sedation of patients and children.     

Ovarian fibromas: MR imaging findings with emphasis on intratumoral cyst formation

Purpose

The purpose of this study was to assess MR imaging findings of ovarian fibromas with emphasis on intratumoral cyst formation.

Materials and methods

MR images with a 1.5-T unit obtained in 17 consecutive patients (age range, 18–87 years; mean age, 58 years) with 17 histologically proven ovarian fibromas were retrospectively reviewed for the size, configuration, signal intensity of solid components, and presence of cystic degeneration and edema within tumor. Size, number, and location of intratumoral cysts were also assessed.

Results

The maximum diameter of tumors ranged from 3.3 to 19.1 cm (mean, 10.9 cm). Seven (41%) tumors were multinodular. On T2-weighted images, solid components of tumors were heterogeneously mixed hypo- and hyperintensity in 16 (94%) tumors. Nine (53%) tumors demonstrated cysts and 16 (94%) demonstrated edema within tumor. The maximum diameter of the largest cysts ranged from 1.0 to 13.2 cm (mean, 6.4 cm), and the number of cysts per tumor ranged from 1 to 60 (mean, 15.6). Of the nine tumors with cystic formation, the predominant location of the cysts was peripheral in five (56%), exophytic in two (22%), central (11%) in one, and diffuse in one (11%).

Conclusion

Peripheral or exophytic cyst formation may be characteristic MR imaging features with ovarian fibromas.     

Magnetic resonance spectroscopy and perfusion weighted imaging as predictors for tumor response to gamma knife radiosurgery: A single center experience

Objective

To test the hypothesis that hemodynamic and metabolic characteristics of intracranial neoplasms detected with magnetic resonance spectroscopy and perfusion weighted imaging are efficient predictors of tumor response to radiosurgery.

Methods

Fifty-four patients with 59 intracranial neoplasms, who underwent evaluation with echoplanar PW and MRS imaging prior to gamma knife radiosurgery were selected for this retrospective analysis. The mean irradiation dose was 13.76 Gy. The mean follow up after GNR constituted 24 months. Predictive diagnostic accuracy was calculated with standard formulas. The association of tumor response to radiosurgery with pretherapeutic MRI parameters was estimated using the Mann–Whitney U test.

Results

Significant association was found between the perfusion and hemodynamic parameters of intracranial neoplasms and the outcome of GKR. Diagnostic accuracy of multimodel MRI was 89% among low grade and 65% among high grade neoplasms. The overall accuracy was 81%. Normalized rCBV, choline, NAA and lipid contents and Chol/cr and NAA/cr were statistically different between low and high grade neoplasms (p < 0.001).

Conclusion

MR perfusion and spectroscopic results provided information that were predictive of the outcome of radiosurgery in this patient pool, increased the diagnostic accuracy of conventional MRI in defining tumor type and grade and may play an important role in pre-therapeutic planning for radiosurgery.     

Can diffusion weighted imaging distinguish between benign and malignant solid or predominantly solid gynecological adnexal masses?

Objective

To determine the benefit of DWI in diagnosis of benign and malignant solid or predominantly solid gynecological adnexal or ovarian masses.

Material and Methods

This study is carried out on 23 patients with histologically proven solid or predominantly solid adnexal or ovarian masses out of which 5 cases (21.8%) have benign and 18 cases (78.2%) have malignant neoplasms. Among these 19 cases (82.6%) have unilateral disease and 4 cases (17.4%) have bilateral disease which was metastatic ovarian carcinoma.

Result

On DWI, high signal intensity is noted in malignant lesion more frequently than in benign lesion. (P < 0.001) in adnexal lesions, while in ovarian lesions (P = 0.001).The differentiation between benign and malignant adnexal lesions revealed no significant difference in the apparent diffusion coefficient (ADC) value (P = 0.22).

Conclusion

DWI is a helpful tool in differentiation between predominantly solid and solid benign and malignant adnexal lesions because there is an increased frequency of higher signal intensity (diffusion restriction) in malignant lesions.     

Utility and limitations of 3-Tesla diffusion-weighted magnetic resonance imaging for differentiation of renal tumors

Objective

To investigate utility and limitations of 3-Tesla diffusion-weighted (DW) magnetic resonance imaging (MRI) for differentiation of benign versus malignant renal lesions and renal cell carcinoma (RCC) subtypes.

Materials and methods

Sixty patients with 71 renal lesions underwent 3 Tesla DW-MRI of the kidney before diagnostic tissue confirmation. The images were retrospectively evaluated blinded to histology. Single-shot echo-planar imaging was used as the DW imaging technique. Apparent diffusion coefficient (ADC) values were measured and compared with histopathological characteristics.

Results

There were 54 malignant and 17 benign lesions, 46 lesions being small renal masses ≤4 cm. Papillary RCC lesions had lower ADC values (p = 0.029) than other RCC subtypes (clear cell or chromophobe). Diagnostic accuracy of DW-MRI for differentiation of papillary from non-papillary RCC was 70.3% resulting in a sensitivity and specificity of 64.3% (95% CI, 35.1–87.2) and 77.1 (95% CI, 59.9–89.6%). Accuracy increased to 83.7% in small renal masses (≤4 cm diameter) and sensitivity and specificity were 75.0% and 88.5%, respectively. The ADC values did not differ significantly between benign and malignant renal lesions (p = 0.45).

Conclusions

DW-MRI seems to distinguish between papillary and other subtypes of RCCs especially in small renal masses but could not differentiate between benign and malignant renal lesions. Therefore, the use of DW-MRI for preoperative differentiation of renal lesions is limited.