Efficacy of 3D VIBE Dixon fat quantification for differentiating clear-cell from non-clear-cell renal cell carcinoma.

AIM: To assess the efficacy of three-dimensional (3D) volumetric interpolated breath-hold examination (VIBE) magnetic resonance imaging (MRI) with Dixon quantification for differentiating clear-cell from non-clear-cell types of renal cell carcinoma (RCC). MATERIALS AND METHODS: The 3D VIBE Dixon renal MRI examinations of 44 patients with 45 histologically confirmed RCCs was analysed. The fat fractions and signal intensity indexes (SIindex) of the solid portions of clear-cell and non-clear-cell RCCs were measured and compared using Student's t-test and receiver operating characteristic (ROC) curves. The agreement of measurements among observers was evaluated by the intraclass correlation coefficient (ICC), and Bland-Altman plots. RESULTS: The mean values of fat fraction (13.16±7.16%) and SIindex (22.64±15.7%) in clear-cell RCCs were significantly higher than that in non-clear-cell RCCs (7.7±2% and 7.9±4.8%; p<0.001, respectively). With the area under the ROC curve (AUC) of the fat fraction at 0.811, 75% (95% CI: 55.1-89.43%) sensitivity and 76.5% (95% CI: 50.1-93.2%) specificity for diagnosing clear-cell RCC were obtained at a cut-off fat fraction value of 8.9%. With a cut-off value of 8.89%, the diagnostic sensitivity and specificity were 85.7% (95% CI: 67.3-96%) and 70.6% (95% CI: 44-89.7%), respectively. The AUC of the SIindex was 0.870 (0.766-0.973). ICC and Bland-Altman plots show excellent agreement of the tumour fat fraction and SIindex measurement between the two observers. CONCLUSION: Intracellular lipid content analysis using the 3D Dixon technique can help to differentiate clear-cell from non-clear-cell RCCs.

Preliminary study of diffusion-weighted MRI in the preoperative diagnosis of cystitis glandularis.

AIM: To assess the efficacy of diffusion-weighted (DWI) magnetic resonance imaging (MRI) in distinguishing cystitis glandularis (CG) from bladder urothelial carcinoma. MATERIALS AND METHODS: Ultrasound, computed tomography (CT), conventional MRI, and DWI of 30 patients with histopathologically confirmed CG were analysed retrospectively and the imaging findings were correlated to the findings at histology. RESULTS: Ultrasound was non diagnostic in 11/18 and misdiagnosed malignancy in 7/18; CT was non diagnostic in 6/10 and misdiagnosed malignancy in 4/10; MRI was non diagnostic in 0 and misdiagnosed malignancy in 4/5 respectively. One patient with diffuse bladder wall thickening was correctly diagnosed as CG at MRI. All six patients who underwent additional DWI were accurately diagnosed as having CG with no or minimal reduction of diffusion. CONCLUSIONS: Diffusion is not reduced or shows minimal reduction in CG. DWI may aid the differential diagnosis of CG.

Value of normalized apparent diffusion coefficient for estimating histological grade of vesical urothelial carcinoma.

AIM: To compare the efficacy of apparent diffusion coefficient (ADC) and normalized ADC (nADC) for estimating the histological grade of vesical urothelial carcinoma and to identify an optimal reference for nADC calculation. MATERIALS AND METHODS: Thirty patients with histologically confirmed vesical urothelial carcinomas underwent preoperative diffusion-weighted magnetic resonance imaging (DW-MRI) of the pelvis. nADC of the tumour was calculated as ADC (tumour)/ADC (reference) using urine in the bladder lumen, and the obturator internus and gluteus maximus muscles as reference. Receiver operating characteristic (ROC) curves were constructed and compared to identify an optimal reference for nADC calculation. RESULTS: Both ADC and nADC of low-grade tumours (1.112 ± 0.159 × 10(-3) mm(2)/s, 0.403 ± 0.047 × 10(-3) mm(2)/s) were significantly (p < 0.001) higher than those of high-grade tumours (0.772 ± 0.091 × 10(-3) mm(2)/s, 0.276 ± 0.033 × 10(-3) mm(2)/s). The area under the nADC ROC curve using urine as reference was significantly (p = 0.000) larger (0.995) than those using obturator internus (0.960) and gluteus maximus (0.945). CONCLUSIONS: nADC is superior to ADC for estimating the histological grade of bladder carcinoma using urine in the bladder lumen as an optimal reference for nADC calculation.

Tuberculosis of the parotid gland: computed tomographic findings.

BACKGROUND: Tuberculosis (TB) of the parotid gland is rare, even in endemic regions. Approximately 100 cases have been reported in the English literature. The computed tomographic (CT) features, however, have seldom been studied. PURPOSE: To determine the diagnostic CT features of tuberculosis of the parotid gland. MATERIAL AND METHODS: CT studies of four histologically proven cases of tuberculosis of the parotid gland were retrospectively reviewed. RESULTS: A total of 15 enlarged lymph nodes were found in the superficial lobes of the parotid glands. The nodes were arranged linearly within the gland. Enhancement patterns included homogeneous enhancement (9/15, 60%), homogeneous enhancement with eccentric microcysts (3/15, 20%), and thick-walled rim enhancement with central lucency (3/15, 20%). Thickened adjacent fascial plane and platysma were seen in two patients. Ipsilateral cervical lymphadenopathy was seen in all patients. CONCLUSION: In patients presenting with unilateral parotid nodules, TB should be considered when linearly arranged enhancing nodules are demonstrated in the superficial lobes of the glands on CT scan.

Clinical value of proton magnetic resonance spectroscopy for differentiating recurrent or residual brain tumor from delayed cerebral necrosis.

PURPOSE: Delayed cerebral necrosis (DN) is a significant risk for brain tumor patients treated with high-dose irradiation. Although differentiating DN from tumor progression is an important clinical question, the distinction cannot be made reliably by conventional imaging techniques. We undertook a pilot study to assess the ability of proton magnetic resonance spectroscopy (1H MRS) to differentiate prospectively between DN or recurrent/residual tumor in a series of children treated for primary brain tumors with high-dose irradiation. METHODS AND MATERIALS: Twelve children (ages 3-16 years), who had clinical and MR imaging (MRI) changes that suggested a diagnosis of either DN or progressive/recurrent brain tumor, underwent localized 1H MRS prior to planned biopsy, resection, or other confirmatory histological procedure. Prospective 1H MRS interpretations were based on comparison of spectral peak patterns and quantitative peak area values from normalized spectra: a marked depression of the intracellular metabolite peaks from choline, creatine, and N-acetyl compounds was hypothesized to indicate DN, and median-to-high choline with easily visible creatine metabolite peaks was labeled progressive/recurrent tumor. Subsequent histological studies identified the brain lesion as DN or recurrent/residual tumor. RESULTS: The patient series included five cases of DN and seven recurrent/residual tumor cases, based on histology. The MRS criteria prospectively identified five out of seven patients with active tumor, and four out of five patients with histologically proven DN correctly. Discriminant analysis suggested that the primary diagnostic information for differentiating DN from tumor lay in the normalized MRS peak areas for choline and creatine compounds. CONCLUSIONS: Magnetic resonance spectroscopy shows promising sensitivity and selectivity for differentiating DN from recurrent/progressive brain tumor. A novel diagnostic index based on peak areas for choline and creatine compounds may provide a simple discriminant for differentiating DN from recurrent or residual primary brain tumors.

Lymphoscintigraphy in chyluria, chyloperitoneum and chylothorax.

UNLABELLED: Lymphoscintigraphy allows functional assessment of lymphatic transport and depiction of regional lymph nodes, is fast and nontraumatic and has no known side effects. We retrospectively analyzed lymphoscintigraphic studies to determine their efficacy in the investigation of chyluria, chyloperitoneum and chylothorax. METHODS: Twenty-one whole-body lymphoscintigrams using 99mTc-antimony sulfide colloid or dextran were acquired in 18 patients with chyluria, chyloperitoneum and/or chylothorax. The images were reviewed to assess the rate of tracer transport and number, size and distribution of lymph vessels and nodes as well as the presence of collateral, fistula or lymph reflux. RESULTS: Lymphoscintigraphy was normal (5 of 11 patients) or showed lymphatic obstruction (6 of 11 patients) in chyluria associated with filariasis. Lymphatic obstruction was demonstrated in chyloperitoneum and/or chylothorax associated with liver cirrhosis (2 patients), postoperative (1 patient) or congenital (1 patient) lymphatic dysplasia, inferior vena cava obstruction (1 patient) and nephrotic syndrome (1 patient). Enhanced lymph flow was seen in systemic lupus erythematosus (1 patient). Follow-up lymphoscintigrams showed patency of lymphovenous anastomosis (1 patient), improvement (1 patient) or no change (1 patient) in lymphatic drainage after treatment. CONCLUSION: Lymphoscintigraphy can demonstrate abnormal lymphatic drainage in chyluria, chyloperitoneum and chylothorax. It is useful for selecting patients for surgery and assessing the effect of treatment.

Intestinal lymphangiectasia: value of Tc-99m dextran lymphoscintigraphy.

Intestinal lymphangiectasia is a common cause of protein-losing enteropathy characterized by diarrhea, generalized edema, enteric protein loss, hypoproteinemia, and lymphopenia. Diagnosis is based on demonstration of enteric protein loss and characteristic small bowel mucosal histology. Various imaging modalities including barium studies, computed tomography, and lymphangiography have had limited clinical use. The authors report a case of intestinal lymphangiectasia in which Tc-99m dextran lymphoscintigraphy played a significant role in the patient management.

False-normal bone imaging in spinal tuberculosis.

Tc-99m MDP bone imaging in spinal tuberculosis usually shows increased radioactivity at the sites of involvement. Uncommonly, the bone scan can be normal if the infection is low grade, indolent, or severely destructive. Two cases of spinal tuberculosis with normal bone imaging are reported. A normal bone image does not exclude tuberculous spondylitis. If there is clinical suspicion of this disease, further investigations, including tissue specimens, should be obtained.

Imaging of nasopharyngeal carcinoma with Tc-99m MIBI.

PURPOSE: Differentiation of recurrent nasopharyngeal carcinoma (NPC) from radiation fibrosis using conventional diagnostic methods can be difficult. The authors prospectively studied patients with NPC to determine the efficacy of Tc-99m MIBI scintigraphy in detecting the primary, residual, and recurrent tumors. MATERIALS AND METHODS: The authors performed Tc-99m MIBI SPECT studies of the head and neck and whole-body scans on 21 healthy adult volunteers and 43 patients with NPC before (n = 26) or after (n = 17) radiotherapy. The images were qualitatively assessed by comparing the nasopharyngeal uptake to scalp radioactivity. MIBI uptake index was calculated as a ratio of mean counts per pixel in the normal nasopharynx or tumor to mean counts per pixel in the scalp. RESULTS: There was significantly higher uptake of Tc-99m MIBI by NPC than normal nasopharynx and radiation fibrosis (P < .05). The authors determined the optimum cutoff MIBI uptake index value of 1.3 with a sensitivity of 97%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 96%, and an accuracy of 98% for diagnosing NPC. CONCLUSION: This study suggests that Tc-99m MIBI SPECT is useful for detecting primary NPC and for differentiating residual or recurrent tumor from radiation fibrosis. The authors propose the cutoff MIBI uptake index value of 1.3 for diagnosing NPC.

Magnetic resonance imaging of pregnancy in suspected uterine anomaly.

Uterine malformation is associated with higher rate of obstetrical complication. Ultrasound cannot reliably delineate the uterine abnormality, especially in obese women. These two case reports illustrate the value of MRI in depicting the uterine and fetal anatomy, thus assisting the appropriate management of these patients.

Magnetization transfer analysis of brain tumor, infection, and infarction.

Magnetization transfer (MT) imaging has been used to characterize tissues. A prospective analysis of magnetization transfer ratio (MTR) was performed on 107 patients with brain tumors, infection, and infarction to determine its efficacy in differential diagnosis. MTRs of brain tumor, infection, and infarction were significantly lower than those of normal gray and white matter. The cystic centers of infection had significantly higher MTRs than infarct and cystic tumors. The MTRs of infarction were significantly higher than those of cystic low-grade gliomas and benign tumors. The non-enhancing cystic components of infection, low-grade gliomas, and benign tumors were readily distinguished from solid infarction on enhanced images without MT. Using the MTR of 0.01 as a cutoff, the sensitivity, specificity, and accuracy of MT imaging for distinguishing cystic infection from cystic tumors were 90.00%, 75.86%, and 79.49%, respectively. MT imaging may be valuable in differentiating cystic infection from cystic neoplasm. J. Magn. Reson. Imaging 2000;12:395-399.

Comparison of inversion recovery fast spin-echo (FSE) with T2-weighted fat-saturated FSE and T1-weighted MR imaging in bone marrow lesion detection.

OBJECTIVE: To prospectively compare inversion recovery (IR) fast spin-echo (FSE) with T1-weighted spin-echo (SE) and T2-weighted chemical-shift fat-saturated (FS) FSE magnetic resonance sequences in the detection of bone marrow abnormality. DESIGN: Twenty-nine sets of T1-weighted SE [400-640/10-20 (TR/TE)], T2-weighted FS-FSE [2400-3800/91-112/8 (TR/TE/ETL), and IR-FSE [3700-6000/12-14/170/8 (TR/TE/T1/ETL)] images were acquired with a 1.5-T magnet in 27 patients with bone marrow lesions. The visibility, margination, and extent of 41 lesions, image quality, contrast, and artifacts were qualitatively and quantitatively compared. RESULTS: The lesions were more conspicuous on the IR-FSE than on the T1-weighted SE and T2-weighed FS-FSE images. The extent of lesions was similar for all three sequences. Image quality was better and there were fewer motion artifacts on the T1-weighted images. The mean lesion contrasted-to-noise ratio was significantly higher on the T1-weighted images (p < 0.05). CONCLUSION: The IR-FSE sequence is highly sensitive for detecting bone marrow pathology, with scan time comparable to the T1-weighted SE and T2-weighted FS-FSE sequences.

Musculoskeletal melioidosis: clinical and imaging features.

OBJECTIVE: Melioidosis is a tropical infection caused by a gram-negative bacillus, Pseudomonas pseudomallei. The disease manifests initially as localized suppurative lesions and can progress to acute disseminated septicemia with 65-90% mortality if inadequately treated. Musculoskeletal involvement is common. The purpose of this study was to describe the clinical features and imaging appearances of musculoskeletal melioidosis. DESIGN: We retrospectively analyzed the clinical profiles and images of 26 patients diagnosed over a 6-year period as suffering from melioidosis. PATIENTS: The study group comprised 11 patients with musculoskeletal melioidosis and 15 patients with nonmusculoskeletal melioidosis. RESULTS AND CONCLUSIONS: We found that musculoskeletal melioidosis mimicks other infections both clinically and radiologically. Clinical awareness is therefore crucial, as diagnosis can only be established by bacteriological and immunological studies. Prompt treatment with long-term combination antibiotics in high dosages and surgical drainage of abscesses improves survival.

Magnetization transfer imaging diagnosis of intracranial tuberculomas.

Tuberculomas (TB) can mimic brain tumors and abscesses. We performed prospective magnetization transfer ratio (MTR) analysis on 60 patients with 52 intracranial TB, 13 pyogenic abscesses and 65 tumors to determine the efficacy of magnetization transfer (MT) imaging in the differential diagnosis of brain tumors and infection. The nonenhancing cores of TB had significantly higher (P=.026) MTR (0.14+/-0.29) than necrotic components of high-grade gliomas (-0.19+/-0.22). The MTR of cores of TB were also higher than those of the cystic areas of low-grade gliomas (-0.53+/-0.32), benign (-0.09+/-0.21) and malignant (-0.07+/-0.25) tumors, and abscesses (-0.03+/-0.13), but the differences were not significant because of the small number of tumors and abscesses. There was also no significant difference between the MTR of abscesses, malignant and benign tumors. Using the criteria of MTR of necrotic center > 0.14 (mean MTR of TB) for diagnosing TB, MTR <-0.03 (mean MTR of abscesses) for diagnosing tumors and MTR between these values for diagnosing abscesses, MTI had diagnostic sensitivity of 68.42%, specificity of 80.49%, and accuracy of 76.67%. The improved diagnostic accuracy of MRI with the addition of MTR analysis from 86.67% to 91.67% and from 85.71% to 87.50% for both radiologists respectively was not significant. MTR analysis helped us to differentiate solitary TB or abscess from low-grade glioma in five patients and to diagnose multiple TB, abscesses, and metastases in four.

Magnetic resonance imaging findings in tuberculous meningoencephalitis.

OBJECTIVE: To evaluate the efficacy of magnetic resonance imaging (MRI) for distinguishing tuberculosis from other types of meningoencephalitis. PATIENTS AND METHODS: MRIs of 100 patients with tuberculous (50), pyogenic (33), viral (14), or fungal (3) meningoencephalitis were analyzed independently by 2 radiologists. Number, size, location, signal characteristics, surrounding edema, and contrast enhancement pattern of nodular lesions; location and pattern of meningeal enhancement; extent of infarct or encephalitis and hydrocephalus were evaluated. RESULTS: Contrast-enhancing nodular lesions were detected in patients with tuberculous (43 of 50 patients), pyogenic (9 of 33), and fungal (3 of 3) infections. No nodules were detected in patients with viral meningoencephalitis. Using the criteria of 1 or more solid rim or homogeneously enhancing nodules smaller than 2 cm, the sensitivity, specificity and accuracy for diagnosing tuberculous meningitis were 86.0%, 90.0% and 88.0%, respectively. CONCLUSION: Magnetic resonance imaging is useful in distinguishing tuberculous from pyogenic, viral and fungal meningoencephalitis.

Magnetic resonance imaging of splenic hemangiomatosis.

The authors report a case of splenic hemangiomatosis evaluated by magnetic resonance imaging (MRI). Typical areas of hyperintensity were observed in T2-weighted images. Because it is noninvasive and highly sensitive, MRI proved valuable in suggesting the diagnosis in this patient.

MR imaging of the brain: comparison of gradient-echo and spin-echo pulse sequences.

OBJECTIVE: Gradient-echo pulse sequences can reduce imaging time and decrease motion artifacts. If gradient-echo pulse sequences are shown to be comparable to spin-echo sequences in MR imaging of the brain, then gradient-echo imaging can be valuable for examining critically ill, anxious, or uncooperative patients and can increase patient throughput. The purpose of this study was to prospectively compare one fast multiplanar spoiled gradient-recalled acquisition in the steady state (GRASS) (FMPSPGR) sequence with one conventional T1-weighted spin-echo sequence to determine the reliability of the FMPSPGR sequence for detecting cerebral lesions. SUBJECTS AND METHODS: Fifty-one patients with 142 cranial lesions, including brain tumors, infarction, infection, and noninflammatory lesions, were examined. Forty-two unenhanced and 39 contrast-enhanced FMPSPGR (113-240/2.6-3.6/90 degrees/4 [TR/TE/flip angle/acquisitions]) and spin-echo T1-weighted (400-579/11-12/90 degrees/2) MR images of the head were obtained with a 1.5-T system. The visibility, margination, and extent of the lesions; image quality; contrast; and artifacts were qualitatively and quantitatively compared. RESULTS: Supratentorial lesions were more conspicuous on the unenhanced FMPSPGR images because of the higher signal-to-noise ratio of the normal brain resulting in higher lesion contrast. The higher contrast-to-noise ratio of neoplasms on the contrast-enhanced spin-echo images was not found to be significant in the independent qualitative analysis. The conspicuity and extent of other lesions evaluated with the two pulse sequences were not significantly different for either the unenhanced or the contrast-enhanced studies. Vascular pulsation artifacts were significantly reduced on the contrast-enhanced FMPSPGR images. Susceptibility and chemical-shift phase-cancellation artifacts were more pronounced on the FMPSPGR images. CONCLUSION: The FMPSPGR sequence provides high-quality images with fewer vascular pulsation artifacts three to four times faster than the spin-echo sequence. The FMPSPGR sequence can reliably show intracranial lesions and can substitute for the T1-weighted spin-echo sequence in routine brain imaging.

Value of magnetic resonance myelography in the diagnosis of disc herniation and spinal stenosis.

Magnetic resonance imaging provides a good-quality image over the entire length of the spine and can assess the morphology of the discs and cord. It is the imaging modality of choice in the investigation of spinal diseases. Magnetic resonance myelography (MRM) is non-invasive, has comparable sensitivity to conventional myelography in visualizing lumbar nerve roots and allows overall assessment of the spinal canal even in the presence of cerebrospinal fluid block. Seventy-two patients with pre-surgical diagnosis of disc herniation were prospectively investigated prior to surgery to determine the value of MRM in the diagnosis of disc herniation and spinal stenosis. The difference between the sensitivity and accuracy of MRI (89.0-95.6%, 89.1-95.7%) and MRM (82.4-89.0%, 82.6-89.1%) was not significant for both observers. There was no significant improvement with the addition of MRM to MRI (91.2-97.8%, 91.3-97.8%). Although MRM did not significantly improve the diagnostic accuracy of MRI, it allowed a better overall view of the dural sac and root sleeves, therefore making it easier to diagnose spinal stenosis and disc herniation in a minority of cases.