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 (SI_index) 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 SI_index (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 SI_index was 0.870 (0.766-0.973). ICC and Bland-Altman plots show excellent agreement of the tumour fat fraction and SI_index 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.

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.

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 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.

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.

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.

Computed tomography of retroperitoneal paragangliomas

More than 10% of retroperitoneal paragangliomas are malignant. Histopathological appearance is unreliable in distinguishing benign from malignant paragangliomas. In this study the computed tomography (CT) features of retroperitoneal paragangliomas were analysed to determine if benign neoplasms could be distinguished from malignancy by their appearance at imaging. We reviewed the clinical profiles and CT scans of 27 benign and seven malignant retroperitoneal paragangliomas in 32 patients to determine the presence of any characteristic appearances of benign and malignant neoplasms. Extra-adrenal paragangliomas were more frequently malignant (50%) than adrenal neoplasms (12.5%). Benign lesions were generally smaller (average 6.1 cm) than malignant lesions (average 7.9 cm). Benign tumours were more likely to be homogeneous (46.2%) and have well-defined margins (92.3%) than malignant tumours (25 and 12.5% respectively). Larger tumours were more frequently necrotic. Malignant retroperitoneal paragangliomas infiltrated adjacent liver, pancreas, bowel, lymph nodes, blood vessels, or metastasized to bone and liver. Malignant retroperitoneal paragangliomas are frequently extra-adrenal, large and heterogeneous, with ill-defined margin and necrosis. CT is useful for delineating the location, extent and nature of these tumours. Infiltration of surrounding tissues or organs, metastases, and resectability are accurately assessed by CT.

Imaging diagnosis of abdominal and pelvic sarcomas

Sarcomas of the abdomen and pelvis are rare malignant mesenchymal neoplasms that often remain undiagnosed until they attain large size. Complete tumour resection is associated with improved patient survival. Detection and delineation of the tumour, its extent and its relationship with surrounding tissues are important for surgical planning. Radiography, barium studies, and intravenous urography are of limited value in the imaging diagnosis of abdominal and pelvic sarcomas. Ultrasound is sensitive for detecting neoplasms larger than 6 cm. Computed tomography is useful for detection, defining extent, and predicting resectability of the primary tumour, evaluation of response to treatment, and detecting recurrence and metastasis. Sarcomas are predominantly large, poorly demarcated, heterogeneous masses of muscle density with haemorrhage or necrosis.

Primary intrathoracic malignant fibrous histiocytoma and angiosarcoma

Primary intrathoracic malignant fibrous histiocytoma and angiosarcoma are rare sarcomas constituting less than 0.2% of lung cancers. The typical imaging appearance is a large, well-circumscribed, non-cavitating, non-calcified, peripheral lung mass without hilar or mediastinal lymphadenopathy. Bronchoscopy and percutaneous needle aspiration are of limited value in differential diagnosis, and thoracotomy is warranted for definitive diagnosis.

Computed tomography of abdominal neurogenic tumours

Abdominal and pelvic neurogenic tumours are uncommon neoplasms in adults apart from those tumours found in patients with neurofibromatosis. Malignant degeneration occurs in 2.4-29% of neurofibromatosis. Biopsy of neurofibromas can be complicated by sensorimotor nerve deficit. Distinction of malignancy by imaging may circumvent biopsies of asymptomatic benign neurogenic tumours. Benign neurogenic neoplasm is suspected on CT scan if the tumour is in the region of known nerve ganglia or pathway, and is well demarcated, solid, homogeneous, hypodense relative to muscle, and enhances with contrast material. Malignant neurogenic tumours are often large, irregular, infiltrative, and necrotic with heterogeneous contrast enhancement. Computed tomography is valuable in distinguishing malignant from benign neurogenic neoplasms, predicting resectability, detecting distant metastases, and evaluating response to treatment.

Lymphoscintigraphy in chyluria, chyloperitoneum and chylothorax

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.

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.

Lymphangioma: imaging diagnosis

Lymphangiomas are congenital malformations of the lymphatics that are curable by extirpation. Accurate delineation of lesion extension is important for pre-operative diagnosis, surgical planning, and assessing recurrence. The radiologic findings were retrospectively evaluated to determine the imaging appearance of these benign tumours. The plain radiographs, barium meal, ultrasound, CT, and MR images of 18 patients with one or more pathologically proved lymphangiomas were reviewed. Plain radiography and barium study showed masses displacing adjacent organs. Ultrasound examination showed uni- or multilocular cystic masses with smooth, thin or irregular, thick walls. Enhancement of the cyst wall was variable on CT and MR studies. The CT density of the fluid ranged from -4 to 34 HU depending on the lipid content and the presence of haemorrhage. The cysts were isointense to muscle on T1-weighted and hyperintense to fat on T2-weighted MR images. The MR imaging delineated the tumour lesion extension more clearly than ultrasound and CT scans. Ultrasound, CT, and MR imaging are valuable for evaluating lymphangiomas. Magnetic resonance imaging allows accurate determination of lesion extension.

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.

Magnetic resonance imaging of musculoskeletal lesions: comparison of three fat-saturation pulse sequences

Fat-saturation (FS) pulse sequences can improve the detection of musculoskeletal lesions. We prospectively compared contrast-enhanced T1-weighted FS spin-echo (SE) images, T2-weighted FS fast spin-echo (FSE) images and inversion recovery (IR) FSE images to determine if any of these three pulse sequences is superior for depicting bone marrow and soft tissue lesions. T1-weighted FS-SE images (400-680/10-20 [TR/TE]) after intravenous injection of gadolinium-diethylenetriaminepentaacetic acid (DTPA), T2-weighted FS-FSE (2400-4200/96-112) and IR-FSE (3700-6000/12-14/170 [TR/TE/TI]) images were obtained with a 1.5-T magnet system in 35 patients. The visibility, margination and extent of 37 bone marrow and 67 soft tissue lesions, image uniformity, susceptibility and motion artefacts were qualitatively analysed by four radiologists. The number and size of lesions detected, the mean lesion signal-to-noise ration (S/N) and contrast-to-noise ratio (C/N) were also statistically compared. More bone and soft-tissue lesions were detected on the IR-FSE and T2-weighted FS-FSE than the T1-weighted FS-SE images. The IR-FSE images were significantly better than the T2-weighted FS-FSE and T1-weighted FS-SE images for bone marrow lesions conspicuity (P < 0.01). The soft-tissue lesions were also more conspicuous on the IR-FSE and T2-weighted FS-FSE images than on the T1-weighted FS-SE images (P < 0.005). The lesion extent and image quality were similar on all three sequences while motion artefacts were most severe on the IR-FSE and least severe on the T1-weighted FS-SE images (P < 0.001). Fat saturation was maximal on the IR-FSE images, resulting in a significantly higher mean C/N of bone marrow lesions. The mean C/N of soft-tissue lesions was higher on the T2-weighted FS-FSE images although the differences were not significant. The T2-weighted FS-FSE and IR-FSE sequences are superior to the contrast-enhanced T1-weighted FS-SE sequence for depicting musculoskeletal lesions. Bone marrow lesion conspicuity is greater on the IR-FSE images, with comparable scan time and image quality but more motion artifacts.

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.

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.

Bone changes in tuberous sclerosis mimicking metastases

Sclerotic and lytic bone changes of tuberous sclerosis (TS) can mimic bone metastases. We report a case of bone metastases from bronchogenic carcinoma in a patient with TS bone changes. Bone scintigraphy and magnetic resonance imaging are useful in distinguishing the TS bone lesions from bone metastases.

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.

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.

Imaging patterns in melioidosis

Melioidosis is an infectious disease caused by Pseudomonas pseudomallei. It is seldom diagnosed promptly and, if untreated, can lead to an 80-100% mortality rate. Twenty-eight patients with melioidosis were identified over a 6 year period, and their imaging patterns were analysed. Respiratory infections were the commonest form of presentation, frequently shown as diffuse airspace consolidation, and accounted for the highest mortality. Visceral and musculoskeletal infections were associated with chronicity and a high relapse rate. Multifocal splenic abscesses were a common occurrence. Septic arthritis of the knee was frequently seen. The majority of patients had diabetes mellitus and chronic ill-health. An increased awareness of the disease can contribute to its early detection and appropriate treatment.

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.

Granulocytic sarcoma in childhood leukemia: imaging features

PURPOSE

To assess imaging features of granulocytic sarcoma (GS) in children with myelogenous leukemia.

MATERIALS AND METHODS

Retrospectively analyzed were radiographs, bone scintigrams, ultrasound (US) scans, computed tomography (CT) scans, and magnetic resonance (MR) images obtained in 30 patients with acute and one with chronic myelogenous leukemia.

RESULTS

With one exception in which GS antedated leukemia, GS was present concurrently with onset of leukemia or during remission or relapse. Radiographs, nuclear studies, and US findings were nonspecific. One parascapular GS was hyperintense on T2-weighted MR images, but in all eight central nervous system studies, tumors were isointense to gray matter, muscle, or marrow on T1-weighted images and to white matter or muscle, marrow, or both on T2-weighted images. Contrast enhancement of GS was homogenous on cranial CT scans and all MR studies.

CONCLUSION

CT and MR imaging features may allow distinction of GS from hematomas and abscesses, which are also complications of leukemia. Thus, biopsy may be avoided in some patients.

Gd-DTPA enhancement of CSF in meningeal carcinomatosis

OBJECTIVE

We report four cases of CSF enhancement secondary to meningeal carcinomatosis observed during MRI. Only one case has been reported previously.

MATERIALS AND METHODS

Four patients ranging from 4 to 20 years of age, and all having primary or secondary CNS neoplasms, were examined by cranial and/or spinal MRI before and after Gd-DTPA administration. Three of the patients had additional delayed imaging, and subtraction was used in one case.

RESULTS

All four patients demonstrated CSF enhancement after Gd-DTPA administration, which increased on delayed imaging and was more apparent following subtraction. Three of the four patients died within 5 months of the MRI examination.

CONCLUSION

CSF enhancement is uncommon, but when seen indicates massive tumor that coats the surface of the CNS. Detection of CNS enhancement may alter therapy; however prognosis may be poor when CSF enhancement is present. Delayed imaging and subtraction may improve detection of CSF enhancement.

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.