MRI with DWI for the Detection of Posttreatment Head and Neck Squamous Cell Carcinoma: Why Morphologic MRI Criteria Matter.

BACKGROUND AND PURPOSE: Although diffusion-weighted imaging combined with morphologic MRI (DWIMRI) is used to detect posttreatment recurrent and second primary head and neck squamous cell carcinoma, the diagnostic criteria used so far have not been clarified. We hypothesized that precise MRI criteria based on signal intensity patterns on T2 and contrast-enhanced T1 complement DWI and therefore improve the diagnostic performance of DWIMRI. MATERIALS AND METHODS: We analyzed 1.5T MRI examinations of 100 consecutive patients treated with radiation therapy with or without additional surgery for head and neck squamous cell carcinoma. MRI examinations included morphologic sequences and DWI (b=0 and b=1000 s/mm2). Histology and follow-up served as the standard of reference. Two experienced readers, blinded to clinical/histologic/follow-up data, evaluated images according to clearly defined criteria for the diagnosis of recurrent head and neck squamous cell carcinoma/second primary head and neck squamous cell carcinoma occurring after treatment, post-radiation therapy inflammatory edema, and late fibrosis. DWI analysis included qualitative (visual) and quantitative evaluation with an ADC threshold. RESULTS: Recurrent head and neck squamous cell carcinoma/second primary head and neck squamous cell carcinoma occurring after treatment was present in 36 patients, whereas 64 patients had post-radiation therapy lesions only. The Cohen κ for differentiating tumor from post-radiation therapy lesions with MRI and qualitative DWIMRI was 0.822 and 0.881, respectively. Mean ADCmean in recurrent head and neck squamous cell carcinoma/second primary head and neck squamous cell carcinoma occurring after treatment (1.097 ± 0.295 × 10-3 mm2/s) was significantly lower (P < .05) than in post-radiation therapy inflammatory edema (1.754 ± 0.343 × 10-3 mm2/s); however, it was similar to that in late fibrosis (0.987 ± 0.264 × 10-3 mm2/s, P > .05). Although ADCs were similar in tumors and late fibrosis, morphologic MRI criteria facilitated distinction between the 2 conditions. The sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios (95% CI) of DWIMRI with ADCmean < 1.22 × 10-3 mm2/s and precise MRI criteria were 92.1% (83.5-100.0), 95.4% (90.3-100.0), 92.1% (83.5-100.0), 95.4% (90.2-100.0), 19.9 (6.58-60.5), and 0.08 (0.03-0.24), respectively, indicating a good diagnostic performance to rule in and rule out disease. CONCLUSIONS: Adding precise morphologic MRI criteria to quantitative DWI enables reproducible and accurate detection of recurrent head and neck squamous cell carcinoma/second primary head and neck squamous cell carcinoma occurring after treatment.

[Concomitant anosmia and ageusia: a case report]. / Anosmie et agueusie: è propos d'un cas.

Olfactory loss due to head trauma is a frequent finding. It is attributed to the tearing or severing of the olfactory fibers at the cribriform plate. In contrast, posttraumatic gustatory loss is observed and reported rarely and the underlying mechanism is less understood. Here we present a case of a concomitant post-traumatic anosmia and ageusia. Imaging showed a considerable frontobasal brain damage and it is speculated that the gustatory impairment is due to a central injury of the secondary taste cortex. Based on this observation, we believe that this clinical presentation might be much more frequent than previously reported.

Review of the principal extra spinal pathologies causing sciatica and new MRI approaches.

In this paper we illustrate the principal extraspinal pathologies causing sciatica and new approaches for the study of structures such as the lumbosacral plexus (LSP). Visualisation of the LSP in its entirety is difficult with conventional two-dimensional MRI sequences owing to its oblique orientation. In our institution, we have found that the utilisation of three-dimensional short tau inversion-recovery sampling perfection with application-optimised contrasts using different flip angle evolutions sequence is helpful, allowing multiplanar and maximum intensity projection reconstructions in the coronal oblique plane and curvilinear reformats through the plexus. Diffusion tensor imaging enables the observation of microstructural changes and can be useful in surgical planning. The normal anatomy of the LSP, its different extraspinal pathologies and differential diagnoses are thoroughly presented.

Direct Route to Colloidal UHMWPE by Including LLDPE in Solution during Homogeneous Polymerization of Ethylene.

The usual aggregation and precipitation driven by crystallization of nascent PE during homogeneous polymerization of ultra-high molecular weight polyethylene (UHMWPE) is inhibited by including linear low-density polyethylene (LLDPE) in the catalyst solution prior to addition of ethylene monomer. Co-crystallization of newly formed PE and dissolved LLDPE creates a polymer brush on the fold surfaces of the nascent crystallites. Consequently, aggregation is inhibited by steric stabilization. Scanning electron microscopy (SEM) images show that individual lamellae (approximately 10-20 nm thick) typically have lateral dimensions of 0.5 µm × 3.5 µm and form "bowtie" shaped stacks that are approximately 200-500 nm thick. This simple method for stabilizing nascent crystals against precipitation is enabling fundamental studies of their metastable "disentangled" state and may open scalable routes to compounding UHMWPE.