Can unenhanced multiparametric MRI substitute gadolinium-enhanced MRI in the characterization of vertebral marrow infiltrative lesions?

Purpose

To assess the diagnostic effectiveness of unenhanced-multiparametric magnetic resonance imaging (mp MRI) as an alternative to gadolinium (Gad)-enhanced MRI in the characterization of vertebral marrow infiltrative lesions.

Patients and methods

A prospective evaluation of fifty-six patients with suspected or untreated vertebral metastases undergoing MRI of the spine at 1.5 T was carried out. Two groups of sequences were assigned and compared for the characterization of marrow infiltrative lesions: group [A] unenhanced-mp MRI (including T1-weighted, T2-weighted, short time inversion recovery (STIR), diffusion weighted imaging (DWI) and in/opposed phase sequences) and group [B] gadolinium-enhanced MRI (including T1-weighted, T2-weighted, STIR and T1-weighted fat-suppressed gadolinium-enhanced sequence). Qualitative and quantitative image analysis was performed and compared. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for both imaging techniques were calculated.

Results

There was no statistical significant difference between unenhanced-multiparametric MRI and gadolinium-enhanced MRI as regards their diagnostic performance in differentiating benign from malignant vertebral marrow infiltrative lesions (p > 0.05) with calculated sensitivity (94% vs. 97%), specificity (92% vs. 88%), positive predictive value (94% vs. 91%), negative predictive value (92% vs. 95%) and (93% vs. 93%) accuracy.

Conclusion

Unenhanced-multiparametric MRI is compatible with gadolinium-enhanced MRI in reliable characterization of marrow infiltrative lesions. The routine MRI protocol of cancer patients should be altered to accommodate the evolving MRI technology and cost effectively substitute the need for a gadolinium enhanced scan.     

Imaging study of ossifying fibroma with associated aneurysmal bone cyst in the paranasal sinus

Objective

To determine the CT and MR imaging features of ossifying fibroma with aneurysmal bone cyst of the paranasal sinus.

Materials and methods

We retrospectively reviewed 15 patients with histopathology-proven ossifying fibromas with aneurysmal bone cysts in the paranasal sinus. All 15 patients underwent CT and MR imaging. The following imaging features were reviewed: location, shape, margin, CT findings, and MR imaging appearances and time-intensity curve of dynamic contrast-enhanced MR imaging.

Results

Ossifying fibromas occurred in the maxillary sinus in one patient, sphenoid sinus in 2, frontal sinus in 3, frontoethmoid sinuses in 3, and ethmoid sinus in 6 patients. Ossifying fibromas showed an elliptic-shape and aneurysmal bone cysts revealed a multicystic appearance, with well-demarcated margins. On unenhanced CT, ossifying fibromas appeared isodense to gray matter with scattered calcifications in nine, ground-glass appearance in 6 patients and aneurysmal bone cysts showed mixed density. Ossifying fibromas appeared isointense to gray matter in 12 and slightly hypointense in three patients on T1-weighted images, and isointense in 4 and hypointense in eleven patients on T2-weighted images, with moderate or marked enhancement after administration of contrast material. The time-intensity curves of eight ossifying fibromas exhibited a rapidly enhancing and rapid washout pattern. The intracystic components of aneurysmal bone cysts showed heterogeneous signal intensity on MR images, with fluid–fluid levels identified clearly by T2-weighted images, without enhancement. The periphery and septa of aneurysmal bone cysts appeared isointense on MR images, with marked enhancement.

Conclusions

Fluid–fluid levels within an elliptic-shape mass with scattered calcifications or ground-glass appearance is highly suggestive of this complicated entity in the paranasal sinus.     

MR imaging of medullary carcinoma of the breast

Purpose

To examine the magnetic resonance imaging (MRI) findings of medullary carcinoma of the breast and to correlate them with histopathologic features.

Materials and methods

Eight patients were retrospectively evaluated with pathologically confirmed medullary carcinoma of the breast. T1-weighted fat-saturated, T2-weighted fast spine echo, and gadolinium-enhanced fat-saturated fast spoiled gradient-echo images were obtained. Interpretation of the MRI findings was based on evaluation of the configuration, internal signal intensity, contrast enhancement, and type of the time–intensity curve.

Results

Medullary carcinoma showed a lobular shape and a smooth margin, either homogenous or heterogeneous enhancement and delayed peripheral enhancement in the late phase on contrast-enhanced MRI, and either a plateau or washout type with rapid initial rise on the time–intensity curve of the dynamic study.

Conclusion

Although the MRI findings showed a close relationship with histopathologic features of medullary carcinoma, it was difficult to differentiate medullary carcinoma from other histologic types of invasive breast carcinomas.     

Role of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) in differentiating between benign and malignant breast lesions

Objective

To assess the role of DWI and ADC in differentiating between benign and malignant breast lesions.

Materials and methods

51 patients (age range 24–66 years; mean age 48 years) were included in our study. MRI was done using bilateral fat-suppressed T2- weighted fast spin-echo, STIR, axial T1-weighted fast spin-echo. DWI series were acquired using echo planar imaging pulse sequences incorporated with diffusion gradients and finally dynamic contrast enhancement study was done.

Results

Sixty three lesions were detected in 51 patients included in our study. Twenty one lesions were malignant, three lesions were intermediate and twenty two lesions were fibroadenoma according to the final histopathological study and seventeen lesions were breast cysts. A total of 21 lesions showed lower ADC values than benign lesions and were in the range of 0.76–1.29 × 10⁻³ mm²/s and were diagnosed as malignant breast lesions. The sensitivity and specificity for DWI in the differentiating malignant from benign breast lesions were calculated and showed 95.4% and 97.5%, respectively.

Conclusion

DWI is easy to obtain in short scan time and easy to evaluate, and ADC values can differentiate between benign and malignant breast lesions with high sensitivity and specificity.     

Diagnostic value of dynamic contrast-enhanced MRI for submucosal palatal tumors

Objectives

To evaluate the diagnostic value of dynamic contrast-enhanced MRI (DCE-MRI) for differentiating between benign and malignant tumors in the palate.

Materials and methods

26 patients with submucosal palatal tumors were preoperatively examined using DCE-MRI. Their maximum contrast index (CImax), time of CImax (Tmax), and washout ratios (WR300 and WR600) were determined from contrast index curves. The submucosal palatal tumors were divided into two groups according to their Tmax values: the early enhancement group (Tmax < 300 s) consisted of 9 malignant tumors and 6 benign tumors, while the late enhancement group (Tmax ≥ 300 s) included one malignant tumor and 10 benign tumors. We compared the following DCE-MRI parameters between the benign and malignant tumors: CImax and Tmax in all cases and CImax, Tmax, and the washout ratios in the early enhancement group. In addition, we performed a regression analysis of the relationships between tumor size and DCE-MRI parameters; i.e., CImax, Tmax, and washout ratios, among the malignant salivary gland tumors and pleomorphic adenomas.

Results

In all cases and the early enhancement group, significant differences in Tmax were detected between the benign and malignant tumors (P < 0.001 and P < 0.05, respectively), and the optimal Tmax cutoff value for differentiating between them was found to be 165 s. None of the other parameters displayed significant differences between the benign and malignant tumors. Only the WR600 of the pleomorphic adenomas was significantly correlated with tumor size (R² = 0.92, P < 0.001).

Conclusions

Tmax is a useful parameter for distinguishing between benign and malignant submucosal palatal tumors.     

Hepatic hemangioma: correlation of enhancement types with diffusion-weighted MR findings and apparent diffusion coefficients

Purpose

To correlate hepatic hemangioma enhancement types in gadolinium-enhanced magnetic resonance (MR) images with diffusion-weighted MR findings and apparent diffusion coefficients (ADCs).

Materials and methods

Respiratory-triggered diffusion-weighted MR images (TR/TE, 2422/46 ms; parallel imaging factor, 2; b factor, 500 s/mm²; number of averaging, 6) obtained in 35 patients with 44 hepatic hemangiomas diagnosed by gadolinium-enhanced MR and by follow-up imaging were retrospectively evaluated. Hemangiomas were classified into three enhancement types based on gadolinium-enhanced MR imaging findings: type I, early-enhancement type; type II, peripheral nodular enhancement type; type III, delayed enhancement type. Two blinded readers qualitatively assessed lesion sizes and signal intensities on T2-weighted turbo spin-echo and diffusion-weighted images. The ADCs of hemangiomas were also measured.

Results

No significant difference was observed between the three enhancement types in terms of signal intensities on T2-weighted images. Signal intensities on diffusion-weighted images were lower in the order type I to III (P < .01), and mean ADCs were 2.18 × 10⁻³, 1.86 × 10⁻³, and 1.71 × 10⁻³ mm²/s for types I, II, and III, respectively (P < .01). No correlation was found between lesion sizes and ADCs.

Conclusion

Hepatic hemangiomas were found to have enhancement type dependent signal intensities and ADCs on diffusion-weighted MR images. Further studies will have to substantiate that these diffusion patterns might reflect intratumoral blood flow or perfusion.     

Magnetic resonance enhancement pattern and diagnostic accuracy of gadofluorine M in a rabbit VX2 tumor model: Comparison with gadopentetate dimeglumine

Objective

The purpose of this study was to evaluate the enhancement pattern and the diagnostic accuracy of gadofluorine M in comparison with gadopentetate dimeglumine in a rabbit VX2 tumor model.

Materials and methods

Thirteen rabbits with experimentally induced VX2 carcinomas in the thighs underwent sequential T1-weighted enhancement MR imaging using a 3.0 T MR imager, first with gadopentetate dimeglumine, and then 24 (n = 4) or 4 h (n = 9) later with gadofluorine M. In 4 rabbits with 13 tumors, the time-percentage enhancement (PE; i.e., percentage of signal intensity increase) curve was obtained for up to 24 h for each contrast agent. In 9 rabbits with 49 tumors (random numbers of VX2 tumors were inoculated at random sites in the thigh), 3 readers unaware of the histopathologic results interpreted the MR images and determined the number and conspicuity level of the detected tumors. The reference standard was the histopathology of the specimen.

Results

The time-to-peak PE for gadopentetate dimeglumine was 1 min and gadopentetate dimeglumine showed a rapid washout pattern. The time-to-peak PE for gadofluorine M was 30 min and gadofluorine M showed a plateau enhancement pattern for up to 24 h. The peak PE of gadofluorine M was approximately twice that of the same dose of gadopentetate dimeglumine (108.2 ± 14.8 vs. 51.5 ± 24.0). The sensitivities for detecting VX2 tumors by 3 readers were 89.8% (44/49), 85.7% (42/49), and 95.9% (47/49) for gadopentetate dimeglumine-enhanced MR imaging, and 87.8% (43/49), 89.8% (44/49), and 89.8% (44/49) for gadofluorine M-enhanced MR imaging. No significant differences in the sensitivities existed between the two contrast agents for any reader. However, the conspicuity level of tumors was superior with gadofluorine M-enhanced MR imaging for two readers and similar for the other reader.

Conclusion

Gadofluorine M showed strong and plateau enhancement of tumors for up to 24 h. In the reader study, gadofluorine M showed better conspicuity for VX2 tumors than gadopentetate dimeglumine, but had a similar sensitivity.     

Imaging features of small hepatocellular carcinomas with microvascular invasion on gadoxetic acid-enhanced MR imaging

Objectives

Detection of hepatocellular carcinomas (HCCs) before microvascular invasion (MVI) occurs is important due to the poor outcomes associated with MVI. We retrospectively investigated the imaging features of small HCCs with MVI on gadoxetic acid-enhanced MR imaging.

Methods

Fifty patients (40 men and 10 women; mean age, 54 years) with 58 surgically proven small (2 cm or less) HCCs were evaluated by gadoxetic acid-enhanced MRI. Signal intensities on imaging sequences and the presence of the typical dynamic enhancement pattern (arterial enhancement and washout) were assessed. Fisher's exact tests were performed to evaluate the relationships between the presence of MVI, tumor size, and imaging findings.

Results

None of the 12 small HCCs with diameters of 1 cm or less had MVI, while 15 (33%) of the 46 small HCCs with diameters of 1.1–2.0 cm had MVI (p = 0.025, Fisher's exact test). Among the small HCCs with diameters of 1.1–2.0 cm, all HCCs with MVI showed the typical dynamic pattern and hyperintensity on T2- and diffusion-weighted images. Most HCCs (54 lesions, 93%) were hypointense on hepatobiliary phase images regardless of the presence of MVI.

Conclusions

All small HCCs with MVI showed typical dynamic pattern and hyperintensity on T2-weighted and diffusion-weighted images, while atypical dynamic pattern and size of less than 1 cm in diameter may suggest absence of MVI.     

A comparison of MR sequences for lesions of the parotid gland.

PURPOSETo compare six MR sequences (plain and gadolinium-enhanced fat suppressed T1-weighted spin echo, T2-weighted standard spin echo, fat-suppressed and non-fat-suppressed T2-weighted fast spin echo, and inversion-recovery T2-weighted fast spin echo) in their ability to detect, delineate, and characterize lesions of the parotid gland.METHODSFifty-eight parotid gland lesions imaged on 47 examinations were retrospectively evaluated by three blinded observers. Several outcome-related variables were compared by the above six sequences: imaging time, image quality, anatomic sharpness of parotid space, subjective lesion conspicuity, detected abnormality volume, number of individual lesions or discrete lobulations, conspicuity of invasion into adjacent boundaries and structures, and overall diagnostic value.RESULTSDifferences in the above outcome variables between sequences did not correlate with MR scanner software upgrade level, coil type, or lesion-dependent characteristics. Fat-suppressed fast spin-echo T2-weighted and inversion-recovery fast spin-echo T2-weighted sequences resulted in significantly higher scores for lesion conspicuity, detected abnormality volume, and overall diagnostic value. T1-weighted images resulted in the next highest scores, whereas gadolinium-enhanced T1-weighted and standard spin-echo T2-weighted sequences performed poorly for most parotid lesions.CONCLUSIONMR imaging of the parotid gland should include fat-suppressed, long-repetition-time, fast spin-echo T2-weighted, and T1-weighted sequences. Gadolinium-enhanced images need not be obtained routinely.     

Malignant spiculated breast masses: dynamic contrast enhanced MR (DCE-MR) imaging enhancement characteristics and histopathological correlation

Aim

Spiculation of breast masses is usually the result of significant desmoplastic reaction. Diminished neovascularization is expected due to sparsely dispersed tumor cells within the lesion. This feature can cause differences in enhancement patterns which can cause pitfalls while evaluating MR images as well. Aim of this study is to explore the enhancement characteristics of malignant spiculated masses and to correlate these findings with histopathological features.

Materials and methods

Eighteen spiculated and seventeen non-spiculated masses depicted with mammography were included in the study. MR imaging was performed with 1.5 T magnet with breast coil. In MR imaging, T2-weighted turbo spin echo (TSE) with fat suppression sequence followed by pre- and post-contrast T1-weighted 3D-fast low angle shot (FLASH) sequences were used. Lesions were evaluated according to enhancement characteristics: early phase enhancement (first 2 min; less than 50%, 50–100% and more than 100%), late phase enhancement (2–6 min; persistent, plateau and washout) and inner enhancement pattern (homogenous, heterogenous and rim). Desmoplasia and lymphocyte infiltration was classified as mild, moderate and severe. MR images and histopathological findings (desmoplasia, lymphocyte infiltration and grade) of both groups were compared.

Results

Mean ages of patients in spiculated and non-spiculated-mass groups were 55.07 (41–71) and 47.35 (31–62), respectively. Mean diameter of lesions was 17.3 mm (10–31 mm) for spiculated masses while non spiculated masses were 15.8 mm (6–40 mm). There were statistically significant differences between late phase enhancement, persistent enhancement, plateau and washout (p < 0.05). Intergroup comparison of desmoplasia revealed significant difference between severe versus and mild, moderate (p < 0.05).

Conclusion

Spiculated malignant lesions are supposed to contain intense desmoplastic reaction. On DCE-MR images they can show persistent enhancement pattern more often than non-spiculated lesions.     

Parotid gland: plain and gadolinium-enhanced MR imaging

The purpose of this study was to show the typical appearance of lesions of the parotid gland with plain MR imaging and MR imaging enhanced with gadopentetate dimeglumine. Seventeen patients with inflammatory changes and 43 with benign and malignant tumors were studied. The examinations were carried out with plain T1-weighted sequences with a repetition time (TR) of 500 msec and an echo time (TE) of 25 msec (TR/TE = 500/25), T2-weighted sequences (1,600/90), and gadolinium-enhanced T1-weighted sequences in axial, coronal, and sagittal orientations. For identifying normal anatomic structures such as the facial nerve and the main duct, the administration of gadopentetate dimeglumine was helpful. In inflammatory changes, gadolinium-enhanced images showed no diagnostic advantages. Gadopentetate dimeglumine proved helpful in delineating tumorous lesions and in differentiating benign and malignant lesions. However, an exact differentiation of the different histologic types was not possible. Post-operative fibrosis could be differentiated from recurrent tumors after administration of gadolinium. If a question regarding infiltration or definition of the boundaries of a lesion cannot be answered with non-enhanced MR imaging, gadopentetate dimeglumine administration is advised. However, for routine imaging of the parotid gland, its use is not recommended.     

Renal epithelioid angiomyolipoma: MRI findings

Purpose

To retrospectively analyze the MR imaging presentation of renal epithelioid angiomyolipoma (EAML).

Methods

Retrospective analysis revealed 12 subjects with histologically proven renal EAML who underwent preoperative MRI at our institution between January 2009 and June 2016. Two radiologists reviewed the images in consensus, describing MR imaging features including size, location, growth pattern, signal intensity of tumor, and dynamic enhancement pattern.

Results

Nine women and three men were included. The average maximum tumor diameter was 7.1 cm. Exophytic growth was present in 9/12 cases, mesophytic growth in 2/12, and endophytic growth in 1/12. On T1-weighted images, 2/12 displayed homogeneous isointensity, 1/12 homogeneous hyperintensity, 5/12 heterogeneous hypointensity, and 4/12 heterogeneous hyperintensity. Macroscopic fat was detected in 5/12 cases and microscopic fat in 6/12 cases. On T2-weighted images, 5/12 showed heterogeneous hypointensity, 4/12 heterogeneous hyperintensity, and 3/12 homogeneous hypointensity. On dynamic contrast-enhanced MR images, 7/12 showed a slow washout enhancement pattern, 2/12 a rapid washout pattern, 2/12 progressive enhancement, and 1/12 persistent enhancement. Imaging findings were suggestive of hemorrhage (50%), necrosis (25%), or cystic change (50%) within the tumors. Enlarged vessels were detected in 5/12 cases. One tumor extended into the renal sinus. No metastases were found on the preoperative MR imaging.

Conclusion

Although MRI appearances of renal EAML were various, some MRI characteristics may contribute to suggest the possibility of renal EAML.

     

Added diagnostic value of T2-weighted MR imaging to gadolinium-enhanced three-dimensional dynamic MR imaging for the detection of small hepatocellular carcinomas

Purpose

To assess the added value of T2-weighted MRI to gadolinium-enhanced dynamic MRI for detection of HCCs.

Materials and methods

Two readers retrospectively analyzed MRIs of 115 patients with 131 HCCs (size; 0.6–2.0 cm) that had been diagnosed by histology (n = 41) or imaging findings (n = 90). Two separate blind image analyses of the gadolinium set and the combined T2-weighted imaging and gadolinium sets were performed. Diagnostic accuracy was evaluated using the alternative-free response receiver operating characteristic method with four-point scale. Sensitivity and positive predictive value were also calculated.

Results

For both observers, the Az values and sensitivities with the combined T2-weighed imaging and gadolinium set (mean Az 0.806, sensitivity 84.7) were significantly higher than those with the gadolinium set (mean Az 0.660, sensitivity 59.9) (p < 0.05). The addition of T2-weighted imaging led to a change in diagnosis for 27 lesions by both observers, which at gadolinium set were assigned a confidence level of 1 or 2 but at additional reading of T2-weighted imaging were assigned a confidence level of 3 or 4. For the positive predictive values, each image set showed a similar value for each observer.

Conclusion

The addition of T2-weighted imaging to gadolinium-enhanced 3D dynamic imaging could be helpful in the detection of HCC by increasing reader confidence for HCCs with equivocal findings on gadolinium-enhanced MRIs.     

Warthin tumor of the parotid gland: diagnostic value of MR imaging with histopathologic correlation

BACKGROUND AND PURPOSE: The purpose of our study was to describe the MR imaging appearance of Warthin tumors multiple MR imaging techniques and to interpret the difference in appearance from that of malignant parotid tumors. METHODS: T1-weighted, T2-weighted, short inversion time inversion recovery, diffusion-weighted, and contrast-enhanced dynamic MR images of 19 Warthin tumors and 17 malignant parotid tumors were reviewed. MR imaging results were compared with those of pathologic analysis. RESULTS: Epithelial stromata and lymphoid tissue with slitlike small cysts in Warthin tumors showed early enhancement and a high washout rate (> or =30%) on dynamic contrast-enhanced images, and accumulations of complicated cysts showed early enhancement and a low washout ratio (< 30%). The areas containing complicated cysts showed high signal intensity on T1-weighted images, whereas some foci in those areas showed low signal intensity on short tau inversion recovery images. The mean minimum signal intensity ratios (SIRmin) of Warthin tumor on short tau inversion recovery (0.29 +/- 0.22 SD) (P < .01) and T2-weighted images (0.28 +/- 0.09) (P < .05) were significantly lower than those of malignant parotid tumors (0.53 +/- 0.19, 0.48 +/- 0.19). The average washout ratio of Warthin tumors (44.0 +/- 20.4%) was higher than that of malignant parotid tumors (11.9 +/- 11.6%). The mean apparent diffusion coefficient of Warthin tumors (0.96 +/- 0.13 x 10(-3)mm2/s) was significantly lower (P < .01) than that of malignant tumors (1.19 +/- 0.19 x 10(-3)mm2/s). CONCLUSION: Detecting hypointense areas of short tau inversion recovery and T2-weighted images or low apparent diffusion coefficient values on diffusion-weighted images was useful for predicting whether salivary gland tumors were Warthin tumors. The findings of the dynamic contrast-enhanced study also were useful.     

Computed tomography and magnetic resonance imaging findings of solitary fibrous tumors in the pelvis: Correlation with histopathological findings

Objective

We aimed to analyze the computed tomography (CT) and magnetic resonance imaging (MRI) findings of pelvic solitary fibrous tumors (SFTs) and to improve the diagnostic efficacy for such tumors.

Methods

Six cases of pelvic SFTs confirmed by histopathology were analyzed retrospectively. Of the 6 patients, 4 had undergone CT scanning, and 2 had undergone magnetic resonance imaging. All the patients had undergone unenhanced and contrast-enhanced examinations, and 2 had also undergone dynamic CT enhancement examination. Image characteristics such as shape, size, number, edge, attenuation or intensity for each lesion before and after contrast enhancement were analyzed and compared with the pathomorphology of the tumors.

Results

All the 6 cases showed oval or rounded and well-defined masses. Unenhanced CT images showed heterogeneous masses with patchy, necrotic foci in 3 cases and homogeneous mass in 1 case. None of the tumors showed calcification. Contrast-enhanced CT images showed marked, heterogeneous enhancement in the first and second cases. Dynamic enhancement scan demonstrated mild homogeneous enhancement in the third case and mild prolonged, delayed enhancement and washout in the fourth case. T1-weighted MR images showed heterogeneous mild hypointense lesion with linear hyperintensity in 1 case, and homogeneous isointensity in the other. T2-weighted images showed heterogeneous mixed intensity in 1 case and mostly hyperintensive lesion with hypointense foci in another case. A case showed marked heterogeneous enhancement and another showed marked homogeneous enhancement on contrast-enhanced T1-weighted images.

Conclusion

Radiological findings of pelvic SFTs are variable and nonspecific. However, a well-defined, ovoid or rounded mass with hypointense on MR T2-weighted images and variable enhancement on CT and MR images may suggest the diagnosis of SFTs. Pelvic SFTs should be included in the differential diagnosis of regional tumors.     

Salivary gland tumors: diagnostic value of gadolinium-enhanced dynamic MR imaging with histopathologic correlation

PURPOSE: To evaluate the diagnostic value of gadolinium-enhanced dynamic magnetic resonance (MR) imaging of salivary gland tumors and correlate the MR imaging and histopathologic findings. MATERIALS AND METHODS: Thirty-three salivary gland tumors in 29 patients were examined preoperatively at gadolinium-enhanced dynamic MR imaging. There were 22 benign and 11 malignant tumors. Dynamic contrast material-enhanced MR images were obtained for 5 minutes. Time of peak enhancement (T(peak)) and washout ratio (WR) were determined from time-signal intensity curves (TICs). Microvessel count and cellularity-stromal grade were evaluated histopathologically. The strengths of correlations between T(peak) and microvessel count and between WR and cellularity-stromal grade were statistically analyzed. Statistical analysis was also performed to determine whether any differences among the various histopathologic tumor types existed [corrected]. In a validation study, 13 salivary gland tumors in 13 patients were examined consecutively. RESULTS: At a T(peak) of 120 seconds, malignant tumors could be differentiated from pleomorphic adenomas but not from Warthin tumors. A WR of 30%, however, enabled differentiation between malignant and Warthin tumors. Classification of TICs on the basis of a T(peak) of 120 seconds and a WR of 30% had high sensitivity (91%) and specificity (91%) in the differentiation of benign and malignant tumors. Correlations between T(peak) and microvessel count (P <.0001, rho = -0.800) and between WR and cellularity-stromal grade (P =.0105, rho = 0.572) were significant. The validation study also yielded high sensitivity (100%) and specificity (80%) in the differentiation between benign and malignant tumors. CONCLUSION: Gadolinium-enhanced dynamic MR imaging is useful for differentiating benign from malignant salivary gland tumors.     

Minor salivary gland tumors in the oral cavity: diagnostic value of dynamic contrast-enhanced MRI

Objective

To evaluate the diagnostic value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for minor salivary gland tumors in the oral cavity.

Materials and methods

Thirty-two patients with minor salivary gland tumors were examined preoperatively using DCE-MRI. Their maximum contrast index (CImax), time of CImax (Tmax), Tpeak; i.e., the time that corresponded to the CImax × 0.90, and washout ratios (WR300 and WR600) were determined from contrast index (CI) curves. We compared these parameters between benign and malignant tumors and among the different histopathological types of minor salivary gland tumors. Then, we categorized the patients’ CI curves into four patterns (gradual increase, rapid increase with high washout ratio, rapid increase with low washout, and flat).

Results

Statistically significant differences in Tmax (P = 0.004) and Tpeak (P = 0.002) were observed between the benign and malignant tumors. Regarding each histopathological tumor type, significant differences in Tmax (P < 0.001), Tpeak (P < 0.001), and WR600 (P = 0.026) were observed between the pleomorphic adenomas and mucoepidermoid carcinomas. It was difficult to distinguish between benign and malignant tumors using our CI curve classification because that two-thirds of the cases were classified into the same type (gradual increase).

Conclusion

The DCE-MRI parameters of minor salivary gland tumors contributed little to their differential diagnosis compared with those for major salivary gland tumors. During the diagnosis of minor salivary gland tumors, Tmax is useful for distinguishing between benign and malignant tumors.     

Primary adrenal lymphoma: radiological; pathological, clinical correlation

Objective

The purpose of this study was to analyze CT and MR imaging (MRI) manifestation of primary adrenal lymphoma in order to better understand of this rare disease.

Materials and methods

Six patients (4 men, 2 women; median age, 65.5 years) with pathologically proven primary adrenal lymphoma were retrospectively reviewed. Imaging findings (CT&;MRI, n = 3; only CT, n = 3) were analyzed and correlated with clinical and pathologic findings.

Results

All cases were pathologically proven primary adrenal diffuse large B-cell lymphoma with bilateral lesions in 3 cases respectively. Maximum diameters of the 9 lesions were 6.1–14.8 cm, median 10.5 cm. Seven lesions were round, oval or oblong, and 2 lesions irregular. Seven lesions were well-defined and 2 had ill-defined margins. Unenhanced CT density of 9 lesions and MR signal intensity of T1 weighted images of 6 lesions were similar to that of muscle, and all 6 lesions were hyperintense on T2-weighted MR images. Following intravenous injection of contrast media, 6 lesions had mild enhancement and 3 lesions had moderate enhancement on parenchymal phase imaging. Enhancement was homogenous in three, slightly inhomogeneous in four, and heterogeneous in two. Seven lesions, in 5 cases, infiltrated the adjacent tissues or organs in patients with large tumors.

Conclusion

Primary adrenal lymphoma usually manifests as large, well-defined, soft-tissue masses replacing the adrenal gland with homogeneous or slightly inhomogeneous enhancement. Large tumors especially tend to infiltrate adjacent structures.     

Computed tomography and magnetic resonance imaging findings of peripheral primitive neuroectodermal tumors of the head and neck

Purpose

We aimed to analyze the computed tomography (CT) and magnetic resonance imaging (MRI) findings of peripheral primitive neuroectodermal tumor (pPNET) of the head and neck.

Methods

Eight patients with pPNET of the head and neck confirmed by histopathological examination were analyzed retrospectively.

Results

The average patient age was 8 years. The tumor location in the 8 patients was as follows: maxillofacial region (right, 2; left, 1), left maxillary sinus (1), right masticator space (1), left carotid space (1), right infratemporal fossa (1), and left parotid gland (1). All 5 patients who underwent CT demonstrated ill-defined soft masses and no calcification. Three patients with tumors in the maxillofacial region showed homogeneous small masses and a mild enhancement. The patient with left maxillary sinus tumor showed a heterogeneous mass with patchy, necrotic foci and mild heterogeneous enhancement. The patient with right masticator space tumor showed a heterogeneous mass, and marked heterogeneous enhancement. The T1-weighted images of the patients with right infratemporal fossa, left carotid space, and left parotid gland tumors were isointense. The T2-weighted images were heterogeneous and mildly hyperintense in 2 patients and hyperintense in 1 patient. Heterogeneous intermediate enhancement was demonstrated in 2 patients and mild ring enhancement in 1 patient.

Conclusion

The imaging features of pPNET of the head and neck are non-specific. An ill-defined, aggressive mass and variable enhancement on CT and MR images may suggest the diagnosis of pPNET. Peripheral PNET should be included in the differential diagnosis of children and adolescents’ regional tumors.     

Differential diagnosis between metastatic tumors and nonsolid benign lesions of the liver using ferucarbotran-enhanced MR imaging

Purpose

To evaluate ability of ferucarbotran-enhanced MR imaging (MRI) in differentiating metastases from nonsolid benign lesions of the liver according to signal-intensity characteristics.

Materials and methods

Sixty-six consecutive patients, who had 138 focal hepatic lesions (26 cysts, 11 hemangiomas, and 101 metastases), underwent ferucarbotran-enhanced MRI. The signal-intensity pattern of each kind of lesion relative to the liver parenchyma on ferucarbotran-enhanced T2* and heavily T1-weighted gradient-echo images were assessed and categorized into the following three categories: high-intensity and iso-intensity, respectively (category A), high and low (category B), and iso- and low-intensity (category C). For category B, lesions were subdivided into two groups based on single-shot half-Fourier RARE images: category B1 (not significantly high-intensity) and category B2 (significantly high-intensity).

Results

Category A had 11 hemangiomas and 2 metastatic tumors, category B1 had 97 metastatic tumors, category B2 had 2 metastatic tumors and 9 cysts, and category C had 17 cysts. When a tumor with a signal intensity of category A was considered to be hemangioma, category B1 metastasis, and category B2 and C cyst, the diagnostic accuracy for differentiating these lesions was 97% (134/138).

Conclusion

The combination of signal-intensity pattern on ferucarbotran-enhanced T2*- and heavily T1-weighted gradient-echo MRI has ability to differentiate liver metastases from nonsolid benign lesions. However, T2-weighted single-shot half-Fourier RARE imaging should also be employed to achieve better performance.