Sjögren's syndrome of the parotid gland: value of diffusion-weighted echo-planar MRI for diagnosis at an early stage based on MR sialography grading in comparison with healthy volunteers

PURPOSE

To investigate the value of diffusion-weighted echo-planar imaging (DW-EPI) for quantifying functional changes of the parotid gland in Sjögren's disease and to evaluate whether ADC mapping allows for early diagnosis based on MR sialography grading.

MATERIALS AND METHODS

Using a DW-EPI sequence at 1.5 T (b-factors: 0, 500 and 1000 sec/mm (2)), the parotid glands of 52 healthy volunteers and 13 patients with histologically verified affection of Sjögren's disease were examined. All scans were performed prior to and following gustatory stimulation with 5 ml of lemon juice. ADC maps were evaluated by placing an inordinate region-of-interest (ROI) enclosing the entire parotid gland. Sjögren's disease was graded based on MR sialography findings using a 4-point grading-scale. Statistics included student t-test and kappa-analysis.

RESULTS

In healthy volunteers mean ADCs of 1.14 x 10 (-3 )mm (2) /sec before and 1.2 x 10 (-3) mm (2) /sec after stimulation were observed. Higher ADCs were determined for early-stage Sjögren's disease, averaging 1.22 x 10 (-3) mm (2) /sec before and 1.29 x 10 (-3) mm (2) /sec after stimulation. Advanced disease revealed significantly lower ADCs (0.97 x 10 (-3) mm (2) /sec (p = 0.002) before and 1.01 x 10 (-3) mm (2) /sec (p < 0.001) after stimulation).

CONCLUSION

DW-EPI seems to display functional changes of the parotid gland affected by Sjögren's disease. Combined with MR sialography, it might be a useful tool for discriminating healthy from affected glands and seems to allow differentiation between the early and advanced disease.

Diffusion-weighted echo-planar MR imaging of primary parotid gland tumors: is a prediction of different histologic subtypes possible?

BACKGROUND AND PURPOSE

Our aim was to determine the value of echo-planar diffusion-weighted MR imaging (epiDWI) in differentiating various types of primary parotid gland tumors.

MATERIALS AND METHODS

One hundred forty-nine consecutive patients with suspected tumors of the parotid gland were examined with an epiDWI sequence by using a 1.5T unit. Image analysis was performed by 2 radiologists independently, and the intraclass correlation coefficient was computed. Histologic diagnosis was obtained in every patient. For comparison of apparent diffusion coefficients (ADCs), a paired 2-tailed Student t test with a Bonferroni correction was used.

RESULTS

In 136 patients, a primary parotid gland tumor was confirmed by histology. Among the observers, a high correlation was calculated (0.98). ADC values of pleomorphic adenomas were significantly higher than those of all other entities, except for myoepithelial adenomas (P = .054). ADC values of Warthin tumors were different from those of myoepithelial adenomas, lipomas, and salivary duct carcinomas (P < .001, 0.013, and .037, respectively). Mucoepidermoid carcinomas, acinic cell carcinomas, and basal cell adenocarcinomas were not differentiable from Warthin tumors (P = .094, .396, and .604, respectively).

CONCLUSION

epiDWI has the potential to differentiate pleomorphic adenoma and myoepithelial adenomas from all other examined entities. Due to an overlap not only within the group of benign and malignant lesions but also between groups, diagnoses should not be addressed on the basis of ADC values solely. Therefore, further studies combining DWI, morphologic criteria, and probably other MR imaging techniques seem warranted.

[Pigmented villo-nodular synovitis and teno-synovial giant-cell tumors]]

Pigmented villo-nodular synovitis (PVS) and teno-synovial giant-cell tumors (TSGCT) are rare diseases of joints, tendon-sheaths and other synovial structures. Regarding PVS the knee joint is the most often involved joint and TSGCT are mostly located in the tendon-sheaths of fingers. Both diseases mostly occur in adults but are also observed in children. Symptoms of both diseases are non-specific. Optimal diagnosis includes an X-ray of the involved structure and a MRI. For PVS optimal therapy is a complete synovectomy, whereas, in TSGCT tumors resection of the tumor itself within marginal margins is sufficient. Because of the high rate of recurrence (up to 50 %) in cases suffering from PVS adjuvant therapeutical strategies such as postoperative radiation or radio-synoviorthesis are recommended. Although there are no significant analyses confirming the effect of an adjuvant therapy on the rate of recurrence scientifically at least there is a tendency that these strategies may reduce the rate of recurrence. Malignant dedifferentiation is rarely seen. The prognosis of the mostly benign disease depends on the extent of the disease, the involved structure, additional bony involvement and still existing degenerative changes. In TSGCT no severe sequelae are known. In contrast, PVS in the hip regularly is followed by a secondary osteoarthrosis, in other joints degenerative changes are depending on the still existing changes at the date of diagnosis. Data on the long-term prognosis are rare and only analysed retrospectively.

[Ultrafast MR sialography: comparison of two coil systems including an alternative surface coil]

PURPOSE

To compare the visualization of salivary ducts by ultrafast magnetic resonance sialography (MR sialography) using an alternative surface coil and a conventional head-neck coil.

MATERIALS AND METHODS

In 11 healthy volunteers, ultrafast MR sialography (single shot turbo spin echo; acquisition time, 2.8 s) was performed before and after oral application of a sialogogue. Each subject received examinations with both a bilateral surface coil (SC) and a conventional head-neck coil (HNC). The depiction of parotideal and submandibular duct systems was graded from 1 to 5 (5 = poor) by four independent radiologists. ANOVA served for statistical analysis of duct rankings, and interobserver variability was determined by Intraclass Correlation Coefficient (ICC).

RESULTS

With an excellent ICC of 0.96, both coil systems offered symmetric visualization of salivary ducts, and the image quality increased after oral application of sialogogue (p < 0.001). In total, the overall rating was worse for SC than for HNC (2.13 +/- 1.24 vs. 1.45 +/- 0.65, p < 0.001). SC was especially inferior in depiction of submandibular and extraglandular duct components compared to HNC (p < 0.001).

CONCLUSION

Most notably due to the reduced visualization of extraglandular and submandibular ducts, the specific surface coil used in this study was inferior in image quality and does not constitute a reasonable alternative to conventional coil systems.

[Detection of metastases in breast cancer patients: comparison of FDG PET with chest X-ray, bone scintigraphy and ultrasound of the abdomen]

Distant metastases at primary diagnosis are a prognostic key factor in breast cancer patients and play a central role in therapeutic decisions. To detect them, chest X-ray, abdominal ultrasound, and bone scintigraphy are performed as standard of care in Germany and many centers world-wide. Although FDG PET detects metastatic disease with high accuracy, its diagnostic value in breast cancer still needs to be defined. The aim of this study was to compare the diagnostic performance of FDG PET with conventional imaging.

PATIENTS, METHODS

A retrospective analysis of 119 breast cancer patients who presented for staging was performed. Whole-body FDG-PET (n = 119) was compared with chest X-ray (n = 106) and bone scintigraphy (n = 95). Each imaging modality was independently assessed and classified for metastasis (negative, equivocal and positive. The results of abdominal ultrasound (n = 100) were classified as negative and positive according to written reports. Imaging results were compared with clinical follow-up including follow-up imaging procedures and histopathology.

RESULTS

FDG-PET detected distant metastases with a sensitivity of 87.3% and a specificity of 83.3%. In contrast, the sensitivity and specificity of combined conventional imaging procedures was 43.1% and 98.5%, respectively. Regarding so-called equivocal and positive results as positive, the sensitivity and specificity of FDG-PET was 93.1% and 76.6%, respectively, compared to 61.2% and 86.6% for conventional imaging. Regarding different locations of metastases the sensitivity of FDG PET was superior in the detection of pulmonary metastases and lymph node metastases of the mediastinum in comparison to chest x-ray, whereas the sensitivity of FDG PET in the detection of bone and liver metastases was comparable with bone scintigraphy and ultrasound of the abdomen.

CONCLUSIONS

FDG-PET is more sensitive than conventional imaging procedures for detection of distant breast cancer metastases and should be considered for additional staging especially in patients with high risk primary breast cancer.

Monitoring of gustatory stimulation of salivary glands by diffusion-weighted MR imaging: comparison of 1.5T and 3T

BACKGROUND AND PURPOSE

Our aim was to compare different field strengths monitoring physiologic changes due to oral stimulation of parotid glands by using diffusion-weighted (DW) echo-planar imaging (EPI).

MATERIALS AND METHODS

Twenty-seven healthy volunteers were examined with a DW-EPI sequence at 1.5T and 3T before and after oral stimulation with commercially available lemon juice. The b factors used were 0, 500, and 1000 s/mm(2). Apparent diffusion coefficient (ADC) maps were evaluated with a manually placed region of interest including the entire parotid gland. For comparison of results, a Student t test was used on the basis of the mean of the volunteer median values. To compare both field strengths, we calculated the Pearson correlation coefficient (r).

RESULTS

DW-EPI MR imaging visualized the parotid glands of all volunteers. With 1.5T, the mean ADC before stimulation was 1.12 x 10(-3) mm(2)/s +/- 0.08 x 10(-3) mm(2)/s. After stimulation with lemon juice, the ADC increased to 1.18 x 10(-3) mm(2)/s +/- 0.09 x 10(-3) mm(2)/s. For 3T, the ADC before stimulation was 1.14 x 10(-3) mm(2)/s +/- 0.04 x 10(-3) mm(2)/s, with an increase to 1.17 x 10(-3) mm(2)/s +/- 0.05 x 10(-3) mm(2)/s after stimulation. For both field strengths, the increase in ADC after stimulation was significant (P < .001). High correlations between both field strengths were found pre- and poststimulation (r = 0.955, and 0.936, respectively).

CONCLUSION

DW-EPI MR imaging allows monitoring of physiologic changes due to oral stimulation of parotid glands by using DW imaging with high correlation between 1.5T and 3T.

Cervical soft tissue imaging using a mobile CBCT scanner with a flat panel detector in comparison with corresponding CT and MRI data sets

OBJECTIVE

The aim of this study was to evaluate soft tissue image quality of a mobile cone-beam computed tomography (CBCT) scanner with an integrated flat-panel detector.

STUDY DESIGN

Eight fresh human cadavers were used in this study. For evaluation of soft tissue visualization, CBCT data sets and corresponding computed tomography (CT) and magnetic resonance imaging (MRI) data sets were acquired. Evaluation was performed with the help of 10 defined cervical anatomical structures.

RESULTS

The statistical analysis of the scoring results of 3 examiners revealed the CBCT images to be of inferior quality regarding the visualization of most of the predefined structures. Visualization without a significant difference was found regarding the demarcation of the vertebral bodies and the pyramidal cartilages, the arteriosclerosis of the carotids (compared with CT), and the laryngeal skeleton (compared with MRI). Regarding arteriosclerosis of the carotids compared with MRI, CBCT proved to be superior.

CONCLUSIONS

The integration of a flat-panel detector improves soft tissue visualization using a mobile CBCT scanner.

Postpancreatectomy hemorrhage: diagnosis and treatment: an analysis in 1669 consecutive pancreatic resections

BACKGROUND

To analyze clinical courses and outcome of postpancreatectomy hemorrhage (PPH) after major pancreatic surgery.

SUMMARY BACKGROUND DATA

Although PPH is the most life-threatening complication following pancreatic surgery, standardized rules for its management do not exist.

METHODS

Between 1992 and 2006, 1524 patients operated on for pancreatic diseases were included in a prospective database. A risk stratification of PPH according to the following parameters was performed: severity of PPH classified as mild (drop of hemoglobin concentration <3 g/dL) or severe (>3 g/dL), time of PPH occurrence (early, first to fifth postoperative day; late, after sixth day), coincident pancreatic fistula, intraluminal or extraluminal bleeding manifestation, and presence of "complex" vascular pathologies (erosions, pseudoaneurysms). Success rates of interventional endoscopy and angiography in preventing relaparotomy were analyzed as well as PPH-related overall outcome.

RESULTS

Prevalence of PPH was 5.7% (n = 87) distributed almost equally among patients suffering from malignancies, borderline tumors, and focal pancreatitis (n = 47) and from chronic pancreatitis (n = 40). PPH-related overall mortality of 16% (n = 14) was closely associated with 1) the occurrence of pancreatic fistula (13 of 14); 2) vascular pathologies, ie, erosions and pseudoaneurysms (12 of 14); 3) delayed PPH occurrence (14 of 14); and 4) underlying disease with lethal PPH found only in patients with soft texture of the pancreatic remnant, while no patient with chronic pancreatitis died. Conversely, primary severity of PPH (mild vs. severe) and the kind of index operation (Whipple resection, pylorus-preserving partial pancreaticoduodenectomy, organ-preserving procedures) had no influence on outcome of PPH. Endoscopy was successful in 3 from 15 patients (20%), who had intraluminal PPH within the first or second postoperative day. "True," early extraluminal PPH had uniformly to be treated by relaparotomy. Seventeen patients had "false," early extraluminal PPH due to primarily intraluminal bleeding site from the pancreaticoenteric anastomosis with secondary disruption of the anastomosis. From 43 patients subjected to angiography, 25 underwent interventional coiling with a success rate of 80% (n = 20). Overall, relaparotomy was performed in 60 patients among whom 33 underwent surgery as first-line treatment, while 27 were relaparotomied as rescue treatment after failure of interventional endoscopy or radiology.

CONCLUSION

Prognosis of PPH depends mainly on the presence of preceding pancreatic fistula. Decision making as to the indication for nonsurgical interventions should consider time of onset, presence of pancreatic fistula, vascular pathologies, and the underlying disease.

Cementless fixation of megaprostheses using a conical fluted stem in the treatment of bone tumours

We reviewed 25 patients in whom a MUTARS megaprosthesis with a conical fluted stem had been implanted. There were three types of stem: a standard stem was used in 17 cases (three in the proximal femur, nine in the distal femur and five proximal tibia), a custom-made proximal femoral stem in four cases and a custom-made distal femoral stem in four cases. The mean age of the patients was 40.1 years (17 to 70) and the mean follow-up was for 2.5 years (0.9 to 7.4).

At follow-up two patients had died from their disease: one was alive with disease and 22 were disease-free. One of 23 prostheses had been removed for infection and another revised to a cemented stem. The mean Musculoskeletal Tumor Society score was 24.9 (12 to 30) and the mean Karnofsky index was 82% (60% to 100%).

There was no radiological evidence of loosening or subsidence. Stem stress shielding was seen in 11 patients and was marked in five of these.

There were five complications, rupture of the extensor mechanism of the knee after extra-articular resection in two patients, deep venous thrombosis in one, septic loosening in one, and dislocation of the hip in one.

The survival rate after seven years was 87% (95% confidence interval (CI) 83 to 91) for the patients and 95% (95% CI 91 to 99) for the megaprosthesis. A longer follow-up is needed to confirm these encouraging results.

Long-term follow-up in small duct chronic pancreatitis: A plea for extended drainage by "V-shaped excision" of the anterior aspect of the pancreas

BACKGROUND

A pancreatic duct diameter (PDD) ranging from 4 to 5 mm is regarded as "normal." The "large duct" form of chronic pancreatitis (CP) with a PDD >7 mm is considered a classic indication for drainage procedures. In contrast, in patients with so-called "small duct chronic pancreatitis" (SDP) with a PDD <3 mm extended resectional procedures and even, in terms of an "ultima ratio," total pancreatectomy are suggested.

METHODS

Between 1992 and 2004, a total of 644 patients were operated on for CP. Forty-one prospectively evaluated patients with SDP underwent a new surgical technique aiming at drainage of the entire major PD (longitudinal "V-shaped excision" of the anterior aspect of the pancreas). Preoperative workup for imaging ductal anatomy included ERCP/MRCP, visualizing the PD throughout the entire gland. The interval between symptoms and therapeutic intervention varied from 12 to 120 months. Median follow-up was 83 months (range, 39-117 months). A pain score as well as a multidimensional psychometric quality-of-life questionnaire was used.

RESULTS

Hospital mortality was 0%. The perioperative (30 days) morbidity was 19.6%. Postoperative, radiologic imaging showed an excellent drainage of the entire gland and the PD in all but 1 patient. Global quality-of-life index increased in median by 54% (range, 37.5%-80%). Median pain score decreased by 95%. Twenty-seven patients (73%) had complete pain relief. Sixteen patients (43%) developed diabetes, while the exocrine pancreatic function was well preserved in 29 patients (78%).

CONCLUSION

"V-shaped excision" of the anterior aspect of the pancreas is a secure and effective approach for SDP, achieving significant improvement in quality of life and pain relief, hereby sparing patients from unnecessary, extended resectional procedures. The deterioration of exocrine and endocrine pancreatic functions is comparable with that observed during the natural course of the disease.

MR-Sialographie: Prospektive Evaluation ultraschneller Sequenzen mit paralleler Bildgebung und oraler Stimulation bei Patienten

PURPOSE

To evaluate an ultra-fast sequence for MR sialography requiring no post-processing and to compare the acquisition technique regarding the effect of oral stimulation with a parallel acquisition technique in patients with salivary gland diseases.

MATERIALS AND METHODS

128 patients with salivary gland disease were prospectively examined using a 1.5-T superconducting system with a 30 mT/m maximum gradient capability and a maximum slew rate of 125 mT/m/sec. A single-shot turbo-spin-echo sequence (ss-TSE) with an acquisition time of 2.8 sec was used in transverse and oblique sagittal orientation. All images were obtained with and without a parallel imaging technique. The evaluation of the ductal system of the parotid and submandibular gland was performed using a visual scale of 1-5 for each side. The images were assessed by two independent experienced radiologists. An ANOVA with post-hoc comparisons and an overall two tailed significance level of p = 0.05 was used for the statistical evaluation. An intraclass correlation was computed to evaluate interobserver variability and a correlation of > 0.8 was determined, thereby indicating a high correlation.

RESULTS

Depending on the diagnosed diseases and the absence of abruption of the ducts, all parts of excretory ducts were able to be visualized in all patients using the developed technique with an overall rating for all ducts of 2.70 (SD +/- 0.89). A high correlation was achieved between the two observers with an intraclass correlation of 0.73. Oral application of a sialogogum improved the visibility of excretory ducts significantly (p < 0.001). In contrast, the use of a parallel imaging technique led to a significant decrease in image quality (p = 0,011).

CONCLUSION

The applied ss-TSE for MR sialography allows fast and sufficient visualization of the excretory ducts of the main salivary glands in patients, and no elaborate post-processing is required. Use of an oral sialogogum is suggested to improve the results of MR sialography.

[Imaging in rheumatology. Degenerative diseases of the spine]

Degeneration of the spine is a common reason for pain in the musculoskeletal system. Radiography is an important tool for diagnosis and differential diagnosis. Cost efficacy and economy of time are advantages in using conventional x-rays. Although narrowing of intervertebral disc spaces, irregular ossification of the vertebral end-plate as well as osteophytes, facet joint osteoarthritis and spondylolisthesis can be observed, early changes in the discs or the subdiscal bone can not be detected by x-rays. Moreover, 3-dimensional imaging is not possible. Computer tomography (CT) and magnetic resonance imaging (MRI) are reliable for identifying disorders of the spine and soft-tissue. Differentiation between inflammation, trauma and tumor is possible. There is still a problem with the relationship between the information obtained by x-rays or MRI and clinical symptoms. Therefore, interpretation of radiological examinations assumes a knowledge of clinical symptoms and the different kinds of diseases which are possible.

Diffusionsgewichtete MRT zur Funktionsdiagnostik der Glandula submandibularis

PURPOSE

To investigate the feasibility of diffusion-weighted (DWI) echo-planar imaging (EPI) to depict the submandibular glands and to measure different functional conditions.

MATERIALS AND METHODS

Twenty-seven healthy volunteers were examined. Diffusion weighted sequence was performed prior to stimulation. Exactly 30 seconds after a commercially available lemon juice was given orally, the diffusion weighted sequence was repeated. All examinations were performed by using a 1.5-T superconducting system with a 30 mT/m maximum gradient capability and maximum slew rate of 125 mT/m/sec (Magnetom Symphony, Siemens, Erlangen, Germany). The lower part of the circularly polarized (CP) head coil and a standard two-element CP neck array coil were used. The flexibility of the neck array coil allowed positioning the N1 element (upper part of the coil) right next to the submandibular gland. The axial diffusion-weighted EPI (echo planar imaging) sequence was performed using a matrix of 119 x 128, a field of view of 250 x 250 mm (pixel size 2.1 x 1.95 mm), a section thickness of 5 mm with an interslice gap of 1 mm. The b factors used were 0 sec/mm(2), 500 sec/ mm(2) and 1000 sec/mm(2). Apparent diffusion coefficiant (ADC) maps were digitally transferred to MRIcro (Chris Rorden, Universitiy of Nottingham, Great Britain). After detecting the submandibular glands a region of interest (ROI) was placed manually exactly within the boarder of both submandibular glands, excluding the external carotid artery on ADC maps. These procedures were performed on all ADC slices the submandibular glands could be differentiated in before and after oral stimulation. For statistical comparison of results, a student's t-test was performed with an overall two-tailed significance level of p = 0.05.

RESULTS

The visualization of the submandibular glands using the diffusion-weighted EPI sequence was possible in all of the 27 volunteers. Prior to oral stimulation an ADC of 1.31 x 10(-3) mm(2)/sec (95 % CI, 1.39 x 10(-3) mm(2)/sec, 1.44 x 10(-3) mm(2)/sec) was calculated which increased to 1.41 x 10(-3) mm(2)/sec (95 % KI, 1.39 x 10(- 3) mm(2)/sec, 1.44 x 10(-3) mm(2)/sec) 30 seconds after stimulation. This increase proved to be significant (p < 0.001).

CONCLUSION

Diffusion-weighted echo-planar MR imaging allows non-invasive quantification of functional changes in the submandibular gland.

Complications of non-compaction of the left ventricular myocardium in a paediatric population: a prospective study

AIMS

Non-compaction of the left ventricular myocardium (NCVM) is reportedly exceedingly rare and associated with a high morbidity and mortality. A different genetic background has been suggested for NCVM with [non-isolated NCVM (ni-NCVM)] and without [isolated NCVM (i-NCVM)] other congenital heart defects. We prospectively evaluated both the NCVM subgroups regarding frequency of occurrence and cardiovascular complications in a paediatric population. Results In a prospective, single-centre study, 66/5220 consecutive patients (1.26%) were diagnosed (25 i-NCVM, 41 ni-NCVM). The median age was 4 years (range 0-21), the median follow-up 12 months (range 0-51). The occurrence of congestive heart failure (CHF) at follow-up was 68.0%. CHF was as frequently seen in i-NCVM and ni-NCVM patients (77.5 vs. 62.1%, P = 0.322). The occurrence of arrhythmias (20.0%) and thrombo-embolic events (13.9%) was not different between subgroups. The cardiomyopathy related mortality was 7.1%, with three and one deaths in the i-NCVM and ni-NCVM groups, respectively (P = 0.126).

CONCLUSION

When prospectively evaluated, NCVM appears to have been previously under-diagnosed. Whereas arrhythmias and thrombo-embolic events were rare, CHF was frequently found. An equally aggressive anticongestive treatment regimen would seem indicated for both the NCVM subgroups.

Die Wertigkeit der Computertomographie des Thorax im Rahmen des Stagings von fortgeschrittenen Kopf-Hals-Malignomen

AIM

At time of diagnosis, up to 17 % of HNSCC present with distant metastasis or a second primary tumour. Distant metastases of these tumours most commonly occur in the lung, requiring a particularly precise evaluation of this organ within the staging process. It was the aim of this study to compare the radiological findings of plain chest X-rays with the results of CT-scans of the chest in regard to their sensitivity for metastasis detection.

PATIENTS AND METHODS

The staging examinations of 47 patients (f: 13, m: 34, mean age: 61.6 y) with progressed (T3, T4, N+) or recurrent HNSCC were prospectively analysed and results of chest X-rays as well as CT-scans of the chest compared.

RESULTS

Only one plain chest X-ray showed a possible metastasis, which was excluded by the following CT-scan. In none of the other 46 patients did X-ray reveal findings of metastatic disease or second primary tumours. CT-scans of the chest showed tumorous lesions in 8/47 (17 %) patients. Three of these tumours were confirmed as neoplastic by biopsy, in another case radiological signs and clinical symptoms permitted definite assumption of malignancy (4/47 : 8.5 %). Histologically, only one of the latter four tumours could be identified as metastatic. In the remaining three cases we found second primary tumours. A follow up CT-scan of one of the remaining four cases showed normal results. In 3 cases the aetiology of the CT-findings remained unclear.

CONCLUSION

Cervical lymph node metastases, tumour-size and recurrence of HNSCC are known risk factors for metastatic disease in HNSCC. Chest X-ray as staging procedure in patients with progressed or recurrent HNSCC may not be able to identify metastases or a second primary tumour of the lung. We therefore recommend a CT-scan of the chest as a routine procedure in such patients to optimise the pre-operative staging.

Diffusion-weighted echo-planar MRI: a valuable tool for differentiating primary parotid gland tumors?

PURPOSE

To investigate the feasibility of using diffusion-weighted (DW) echo-planar imaging (EPI) for differentiating primary parotid gland tumors.

MATERIAL AND METHODS

Fifty consecutive patients with a suspected primary tumor of the parotid gland were examined with a DW EPI sequence (TR 1,500 msec, TE 77 msec, field of view 250 x 250 mm, pixel size 2.10 x 1.95 mm, section thickness 5 mm). The b factors used were 0, 500, and 1,000 sec/mm (2). Apparent diffusion coefficient (ADC) maps were digitally transferred to MRIcro (Chris Rorden, University of Nottingham, Great Britain) and evaluated with a manually placed irregular region of interest (ROI) containing the entire tumor. Additionally, the contralateral, non affected parotid gland was measured and a circular ROI containing 100 - 200 pixels was placed in the cerebrospinal fluid (CSF) next to the spinal cord in every patient. For comparison of the results, the two-tailed Student's t test was used, based on the median ADC values for each patient, and a p-value <.05 was determined to indicate statistical significance.

RESULTS

In 45 patients, a primary neoplasm of the parotid gland could be histologically verified. For the non-affected parotid glands of all 45 evaluated patients, the mean ADC value was 1.14 x 10 ( - 3) mm (2)/sec +/- 0.12 x 10 ( - 3) mm (2)/sec (mean +/- standard deviation). Seven different entities of parotid gland tumors were histologically discriminated. Pleomorphic adenomas (2.14 x 10 ( - 3) mm (2)/sec +/- 0.11 x 10 ( - 3) mm (2)/sec), Warthin tumors (0.85 x 10 ( - 3) mm (2)/sec +/- 0.1 x 10 ( - 3) mm (2)/sec), and mucoepidermoid carcinomas (1.04 x 10 ( - 3) mm (2)/sec +/- 0.3 x 10 ( - 3) mm (2)/sec) showed statistically significant different ADC values in comparison to all other evaluated tumors (p .001), and also among each other (p <.001). Additionally, ADC values presented by lipomas were statistically significant compared to all other entities (p <.001 to .015). Among all other [corrected] primary malignant parotid gland tumors, no statistically significant ADC values could be observed (p .18 to 1).

CONCLUSION

Diffusion-weighted echo-planar MRI seems to be a valuable tool for differentiating benign from malignant primary parotid gland tumors.