Radiation-induced xerostomia: objective evaluation of salivary gland injury using MR sialography.

BACKGROUND AND PURPOSE: Xerostomia (dry mouth) is one of the serious complications of head and neck irradiation and has a strong influence on a patient's activities of daily living. MR sialography with salivary secretion stimulation provides additional functional information (salivary secretion reserve) and may contribute to the evaluation of the severity of xerostomia and predict the risk of developing a radiation-induced xerostomia. This aim of the study was to analyze MR sialography as an objective tool to evaluate radiation-induced salivary injury. MATERIALS AND METHODS: MR sialography with salivary secretion stimulation was performed in 16 patients with head and neck malignancy before and after irradiation therapy. Multivariate (stepwise multiple regression) analysis was performed to analyze the nonstimulated and stimulated MR sialography findings and the clinical severity of xerostomia. RESULTS: Multivariate analysis of the preirradiation study revealed no significant independent variables that could predict the clinical severity of xerostomia. In the postirradiation study, following regression with 2 independent variables (secretion response of the submandibular gland [rSG] and parotid gland visualization on stimulated MR sialography [sPG]) could explain 70% of the cases: xerostomia severity grade = 0.681 + 0.871 x rSG - 0.471 x sPG. CONCLUSIONS: MR sialography is a useful method for visualization of salivary gland radiation injury and estimation of the severity of radiation-induced xerostomia. Insufficiency of secretion reserve at the irradiated submandibular gland has the strongest influence on xerostomia severity. Our investigation suggests that careful submandibular gland protection may lead to prevention and avoidance of radiation-induced xerostomia.

Usefulness of diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging in the diagnosis of prostate transition-zone cancer.

BACKGROUND: Conventional T2-weighted (T2-WI) magnetic resonance imaging (MRI) has poor sensitivity for prostate transition-zone (TZ) cancer detection. PURPOSE: To retrospectively evaluate the clinical value of diffusion-weighted MRI (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) in combination with T2-WI for the diagnosis of TZ cancer. MATERIAL AND METHODS: Twenty-six TZ cancers in 23 patients with at least one tumor (tumor size >10 mm) located predominantly in the TZ were included in the study. Sixteen peripheral-zone (PZ) cancers in 12 patients with PZ cancer but without TZ cancer (control group) were selected by step-section pathologic maps. All patients underwent MRI and radical prostatectomy. MRI was obtained by a 1.5T superconducting system with a phased-array coil. Imaging sequences were T2-WI with fat saturation (FST2-WI), DW-MRI (single-shot echoplanar image, b=0 and 1000 s/mm(2), apparent diffusion coefficient [ADC] map findings), and DCE-MRI (3D fast spoiled gradient recalled [SPGR], contrast medium [0.2 mmol/kg], total injection time 5 s, image acquisition 30, 60, and 90 s). Sensitivity, specificity, accuracy, and positive predictive value (PPV) for the diagnosis of TZ cancer were evaluated in four protocols: A) FST2-WI alone, B) FST2-WI plus DW-MRI, C) FST2-WI plus DCE-MRI, D) FST2-WI plus DW-MRI plus DCE-MRI. RESULTS: Sensitivity, specificity, accuracy, and PPV in protocol A (FST2-WI alone) were 61.5%, 68.8%, 64.3%, and 76.2%, respectively. FST2-WI plus DW-MRI (protocol B) improved the sensitivity, specificity, accuracy, and PPV. In FST2-WI plus DW-MRI plus DCE-MRI (protocol D), the number of true-negative lesions increased and false-positive lesions decreased, and the sensitivity, specificity, accuracy, and PPV were 69.2%, 93.8%, 78.6%, and 94.7%, respectively. There was a significant difference between protocols A and D (P<0.05). CONCLUSION: Adding DW-MRI to FST2-WI in the diagnosis of prostate TZ cancer increased the diagnostic accuracy. The addition of DCE-MRI may be an option to improve the specificity and PPV of diagnosing TZ cancer with FST2-WI and DW-MRI.

Comprehensive MR imaging of acute gynecologic diseases.

Rapid advances in techniques of magnetic resonance (MR) imaging have enabled diagnosis of acute gynecologic conditions, which are characterized by sudden onset of lower abdominal pain, fever, genital bleeding, intraperitoneal bleeding, or symptoms of shock. The chemical-selective fat-suppression technique not only helps establish the characteristics of lesions that contain fat components but also increases the conspicuity of inflammatory lesions. When a T2-weighted image is obtained with a very long effective echo time (>250 msec), even a small amount of ascites can be easily identified and the contrast between urine and complex fluid becomes more conspicuous. T2*-weighted images are useful for identification of hemorrhagic lesions by demonstrating deoxyhemoglobin and hemosiderin. Contrast material-enhanced dynamic subtraction MR imaging performed with a three-dimensional fast field-echo sequence and a rapid bolus injection of gadopentetate dimeglumine allows evaluation of lesion vascularity and the anatomic relationship between pelvic vessels and a lesion and allows identification of the bleeding point by demonstrating extravasation of contrast material. To optimize the MR imaging examination, attention should be given to the parameters of each pulse sequence and proper combination of the sequences.

Ovarian carcinoma in patients with endometriosis: MR imaging findings.

OBJECTIVE: Various types of malignancy can develop in patients with endometriosis. Enhancing mural nodules have been reported as an imaging characteristic of malignant transformations. We evaluated contrast-enhanced MR imaging to determine the optimum sequence to reveal mural nodules and other characteristics of malignant transformations. MATERIALS AND METHODS: We examined 10 patients with pathologically proven ovarian adenocarcinoma in endometriosis and 10 patients (the control group) with ovarian endometrioma suggestive of malignant transformation on the basis of sonographic findings. We analyzed the size and nature of the endometriomas in each patient. We compared four types of contrast-enhanced MR imaging to determine which sequence best revealed mural nodules. RESULTS: In the malignant and control groups, 80% of the cysts with findings suggestive of malignant transformation showed unilateral disease or larger endometrial cysts on the suggestive side than on the contralateral side. High signal intensity on T1-weighted images and low signal intensity on T2-weighted images relative to the myometrium were observed only in two of 10 malignant endometrial cysts and in all control cysts. All malignant endometriomas had small mural nodules with low signal intensity on T1-weighted contrast-enhanced images. Only three benign endometriomas had mural nodules and none of them enhanced. The enhancement of mural nodules was easily seen on dynamic subtraction imaging. CONCLUSION: On the basis of our findings, endometrial cysts with malignant transformation rarely show low signal intensity on T2-weighted images and usually have enhancing mural nodules. Because the enhancement of mural nodules is often difficult to evaluate on conventional T1-weighted images, dynamic subtraction imaging can be valuable.

[MR imaging of the posterolateral aspect of the knee].

The structures of the posterolateral aspect of the knee were evaluated with axial MR images. One hundred twelve knees of clinical cases without posterolateral injury were retrospectively reviewed, and 30 knees of 15 volunteers with no history of knee injury or pain were evaluated. The amount of joint effusion and visualization of the lateral collateral ligament (LCL) and popliteal tendon were classified according to three grades. The LCL and popliteal tendon were identified in 111 clinical cases (99%) and 28 volunteer knees (93%). Visualization of the LCL and popliteal tendon was facilitated in the presence of both joint effusion and fluid collection between the LCL and popliteal tendon. Fluid collection posterior to the femoral attachment of the popliteal tendon was seen in 79 clinical cases (71%) and 20 volunteer knees (67%). Based on cadaveric study, this was considered to be a potential fluid space for communication to the joint space.

Two-dimensional time-of-flight MR venography: assessment with detection of chronic deep venous thrombosis in combination with magnetization transfer contrast.

PURPOSE: The purpose of this study was to determine the optimum imaging parameters for 2D-TOF MR venography (MRV) of the pelvis and suprapopliteal deep venous system in combination with off-resonance magnetization transfer constant (MTC) and to evaluate the use of MRV in patients suspected of having chronic deep venous thrombosis (DVT) by comparing its accuracy with that of conventional venography (CV). METHOD: MRV was performed in 10 normal subjects to determine the optimum imaging parameters. Systematically varied scan parameters included flip angles ranging from 30 to 120 degrees by 10 degrees increments. Best TR was calculated by using the theoretical relation between the optimal TR and flow velocity. We then evaluated the use of MRV in 26 patients (total 52 deep venous systems) suspected of having chronic DVT by comparing its accuracy in evaluating the intrapelvic and suprapopliteal deep venous system with that of CV. RESULTS: The optimal imaging parameters for intrapelvic and suprapopliteal venous system MRV were found to be a flip angle of 60 degrees and a pulse sequence of 35/6.9 (TR ms/TE ms) combined with an off-resonance MTC technique. All the main veins of the intrapelvic and suprapopliteal venous systems were clearly demonstrated in each subject. The sensitivity of MRV was 100% and its specificity was 100% for diagnosis of pelvic venous stenosis. The collateral vessels were demonstrated with MRV in all patients. CONCLUSION: 2D-TOF off-resonance MTC MRV of the pelvis and the suprapopliteal lower extremities is suitable for evaluation of intrapelvic branches and suprapopliteal deep venous system and chronic DVT.

Rectal carcinoma: prospective comparison of conventional and gadopentetate dimeglumine enhanced fat-suppressed MR imaging.

The purpose of this study is to compare the usefulness of conventional MR imaging and gadopentetate dimeglumine enhanced fat-suppressed MR imaging for the depiction and staging of rectal carcinoma. Thirty-two patients were prospectively evaluated by MR imaging using a 1.5-T unit. Based on the results of a barium study and/or digital examination, a balloon catheter was inserted to the level of the lesion before examination. Both conventional T1- and T2-weighted images and gadopentetate dimeglumine enhanced fat-suppressed T1-weighted images were obtained for all patients. The kappa statistics were performed for the evaluation of interobserver agreement and the McNemar test was performed for the analysis of staging accuracy. When only T1- and T2-weighted images were used, 5 of 32 tumors were not detected and the extent of 18 of 32 tumors were unclear. However, when gadopentetate dimeglumine enhanced fat-suppressed imaging was added, 24 of 32 tumors were well defined and only one tumor was not detected. In determining the depth of invasion, the staging accuracy was 72% for conventional imaging and 68% for all images combined. There was no significant difference between with gadopentetate dimeglumine fat-suppressed imaging and conventional imaging (P > .05). Use of gadopentetate dimeglumine (fat-suppressed imaging) resulted in overestimation of muscular invasion, perirectal fat invasion, and adjacent organ invasion in 12 patients, whereas nine patients were overestimated without the use of gadopentetate dimeglumine. In the detection of metastatic lymph nodes, gadopentetate dimeglumine enhanced fat-suppressed imaging also was not useful. Tumor detection was excellent using gadopentetate dimeglumine enhanced fat-suppressed images. However, the accuracy of staging was not improved by obtaining such images.

Malignant vaginal melanoma. Usefulness of fat-saturation MRI.

We present a case of malignant vaginal melanoma studied by magnetic resonance imaging (MRI). A dark irregular mass was noted in the anterior wall of the vaginal cavity on physical examination. On fat-saturated T1-weighted MRI, the vaginal lesion was demonstrated more clearly than by conventional T1- and T2-weighted images. Furthermore, the fat-saturated image detected the bladder metastasis from the vaginal lesion.

[Prostate and prostatic carcinoma: comparison of gadolinium-enhanced MR images and histopathologic findings].

The purpose of this study was to determine the patterns of enhancement in normal prostate, and to compare them with the enhancement patterns and histopathologic findings in patients with prostatic carcinoma. Seventeen patients who had no urogenital disease and 27 who underwent radical prostatectomy or prostatic biopsy were included in this study. All patients were evaluated with T1-, T2-weighted and gadolinium-enhanced T1-weighted images. With gadolinium enhancement the inner gland showed more enhancement than the peripheral zone in the normal prostate. The carcinoma tissue was enhanced more than the peripheral zone in 13 patients, about the same as the peripheral zone in 11 patients, and less than the peripheral zone in three patients. The three patients whose cancer tissue demonstrated no enhancement had poorly differentiated adenocarcinoma of the solid type. In conclusion, gadolinium-enhanced T1-weighted imaging is not reliable for routine use in MR imaging of the prostate, but may be useful to evaluate histologic types in patients with prostatic carcinoma.

[Role of CT in patients with prostatic disease: usefulness of depiction of prostatic zonal anatomy].

The purpose of this study was to evaluate the role of CT in patients with and without prostatic disease. CT and MR findings were reviewed in 25 patients without known prostatic disease, 11 patients with benign prostatic hyperplasia and 11 patients with prostatic cancer. Differential attenuation allowed for distinction of the peripheral zone and inner gland of the prostate by CT in 72% of normal patients. The distinction rate of prostatic zonal anatomy by CT decreased to 30% in the diseased group. When zonal anatomy of the prostate is not visualized on pelvic enhanced CT, the presence of prostatic disease might be considered.

MR imaging of vertebral metastases: evaluation of fat saturation imaging.

OBJECTIVE: To compare conventional T1-weighted imaging (SE-T1) and chemical shift fat-saturation T1-weighted imaging (FS-T1) in the diagnosis of bone metastases. SUBJECTS: Twenty-two patients (101 vertebrae) with non-neoplastic lesions (Group 1) and 21 patients (72 vertebrae) with spinal metastases (Group 2) were evaluated with both images. RESULTS: The signal intensity (SI) distribution of Groups 1 and 2 on SE-T1 showed various patterns, and SI measurement was not significantly different between the two groups. On FS-T1, all non-neoplastic lesions had a low-intensity homogeneous appearance; however, the metastases had mixed to high SI. The SI measurement data of Group 2 was significantly (P < 0.0001) higher than that of Group 1. CONCLUSION: FS-T1 was useful in evaluating vertebral metastases.