Thursday, July 8, 2010

Imaging diagnosis of nasopharyngeal carcinoma compared

Nasopharyngeal carcinoma is the most common head and neck cancer, its diagnosis depends mainly on endoscopic and histological examination, although the CT and MRI evaluation of lesions consistent with the clinical examination, but the spread of nasopharyngeal carcinoma and the surrounding area structure violations, CT and MRI in the clinical examination is different. Now in June 2006 to 2008, 12 pathologically diagnosed as nasopharyngeal carcinoma tissue of 80 untreated patients with CT, MRI examination results are as follows:

1 Materials and Methods

1.1 General Information

June 2006 ~ December 2008 after 80 cases with histopathological diagnosis of nasopharyngeal carcinoma patients with untreated CT, MRI examination intervals of not more than 15 d, of which 42 males and 38 females; age ranged from 16 75 years, mean 60 years; Initial treatment of 30 cases, 50 cases of re-treatment; well-differentiated squamous cell carcinoma in 1 case, 69 cases of poorly differentiated squamous cell carcinoma, vesicular nucleus cell carcinoma in 10 cases; in which the pathological diagnosis was undifferentiated non-angle resistance of cancer 78 cases, differentiated non-keratinizing carcinoma in 2 cases.

Method 1.2

For CT and MRI, which include enhanced diagnostic CT scan, MRI examination included T1, T2 weighted images and enhanced T1-weighted image.

1.2.1 CT diagnosis of nasopharyngeal CT should have the transverse and coronal images. Thickness of 5 ~ 6 mm. Transverse sweep up from the level of soft palate to the level of intracranial suprasellar cistern, coronal to the sella from the nose after the level of the posterior clinoid. CT scan with GE16 spiral CT scanners, to OM line as baseline, scan range from the level of sternoclavicular joint to the saddle on the pool, with the enhanced scan. Scanning parameters for the 140 kV, 320 mA, are used axial scanning, plain and enhanced scans, in addition to soft tissue out of the window to provide the necessary level of bone window. CT scanning level no more than 3 mm. If suspected skull base should be 1 ~ 2 mm of continuous levels of scanning.

1.2.2 MRI diagnosis of MRI scans using 3.0T magnetic resonance imaging, joint head and neck coil. Are as fast spin echo, SE sequence, the scanning direction for the cross-section, sagittal and coronal plane scanning range from the saddle area to the lower edge of 2 cervical vertebrae. Thickness: axial 5 mm, spacing 1.0 mm; coronal, sagittal 4 mm, spacing 0.5 mm. Scan in all cases after the intravenous injection of gadolinium - 2 pentamine acid 0.1 mmol / kg body weight, in accordance with the plain levels T1WI axial, sagittal and coronal enhanced CT scans.

1.3 Statistical analysis

Using SPSS 11.0 software for statistical analysis, with a ratio using χ2 test, P <0.05 for the difference was statistically significant.

2 Results

Nasopharyngeal cavity in the ultra-infringement retropharyngeal lymph node metastasis, skull base and intracranial cavernous sinus area violations, MRI detection rate higher than the CT has obvious advantages, in comparison, the difference was significance (P <0.05).

CT group and the MRI group compared retropharyngeal lymph node metastasis, metastasis detected only between the left common carotid were 20 cases (30.8%) and 24 cases (32.9%), only the transfer of the right neck were 17 cases (26.2%) and 18 cases (24.7%), bilateral neck metastasis were 28 cases (43.1%) and 31 cases (42.5%). Violations of the skull base bone, the detection of the two flange were 6 cases (14.3%) and 9 (13.6%), the slopes were 14 cases (33.3%) and 18 cases (27.3%), petrous apex were 10 cases (23.8%) and 24 cases (36.4%), sphenoid body or sphenoid sinus were 8 cases (19.0%) and 11 cases (16.7%), sphenoid wing were 4 cases (9.5%) and 4 cases (6.1%). Intracranial cavernous sinus, the detection of two groups of unilateral invasion were 60 cases (89.6%) and 67 cases (91.8%), bilateral involvement from the two groups were 7 cases (10.4%) and 6 (8.2 %).

3 Discussion

World Health Organization material showed 80% of the world occurred in China, nasopharyngeal carcinoma, nasopharyngeal carcinoma was highly malignant and often early in the disease, there is infiltration of adjacent structures, its mortality rate Cancer mortality rate ranks first in China 8. With the development of modern medical science, medical imaging in the diagnosis of nasopharyngeal carcinoma has played a very important role. MRI because of its excellent soft tissue contrast and multi-parameter imaging, clearly the change from the morphology and function of tumor location, nature provides a wealth of diagnostic information, and its ultra-nasopharyngeal cavity violation retropharyngeal lymph node metastasis, cranial end abuse and intracranial cavernous sinus bone and other aspects of high sensitivity with a detection rate higher than the CT has obvious advantages.

Application of contrast-enhanced scan and pressure grease is the assessment of nasopharyngeal carcinoma sequence of lesions, grading and staging the best imaging method. The results suggest, CT group and the MRI group in the ultra-cavity violations, retropharyngeal lymph node metastasis, skull base invasion and intracranial cavernous sinus, the number of detected cases and the detection rate was 57 cases (71.3%) and 71 cases (88.8%), 65 cases (81.3%) and 73 cases (91.3%), 42 patients (52.5%) and 66 cases (82.5%), 67 patients (83.8%) and 73 cases (91.3%), MRI than CT showed obvious superiority.

MRI is the use of nuclei generated in the magnetic field resonance signal, the reconstructed image of a technology. Because the magnetic field, the different organizations produce different signals, so the high resolution MRI of the organization, can clearly show the normal structure of the nasopharynx and tumor areas showing the nasopharyngeal mucosa and the palate infiltration Fan levator, tensor fascia violations of the skull base and pharynx level, particularly for soft tissue such as bone marrow signal changes are particularly sensitive, can not display partial destruction of trabecular bone on bone marrow cavity of tumor infiltration. Because CT and MRI diagnosis of skull base mechanism on different skull base early, CT performance may be normal, but MRI showed tumor replaced by yellow marrow signal change, able to distinguish the lesions of fibrosis after radiotherapy, and tumor recurrence.

Functional MRI of the number of sequences, such as the slope dynamics can be used to identify tumor infiltration or radiation therapy after bone damage caused by bone necrosis. When the NPC through the oval foramen into the intracranial and other natural channel when, CT can show the increase of channels and violations of the edge, MRI showed soft tissue signal is on the soft tissue and high resolution imaging by multi-directional, more accurate than the CT picture of the extent of tumor invasion, cavernous sinus lesions found in advance on the diagnosis. Rich base of the skull bone marrow, is the birthplace of distant metastasis, local recurrence after radiotherapy is a major factor, the rate was 14.5% ~ 57.7%, or even as high as 76.9%.

Many patients because of inadequate treatment, not in time they pass leading to local recurrence and distant metastasis. Therefore, accurate to judge whether the violation of nasopharyngeal carcinoma skull base, help determine the correct treatment and prognosis of clinical significance. As the high-resolution MRI of soft tissue, can show the scope of nasopharyngeal carcinoma, avoiding the complexity of skull base anatomy, location, and other deeper problems, the detection rate of the skull base is superior to CT. Skull base combination of clinical and imaging features, diagnosis and design of radiation can target, according to avoid leakage and reduce the recurrence rate of nasopharyngeal cancer, improve survival, the clinical determination of patients with newly diagnosed nasopharyngeal carcinoma more valuable, particularly is a violation of the NPC patients with skull base is particularly important.

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