Simultaneous PET/MR head-neck cancer imaging: Preliminary clinical experience and multiparametric evaluation.

PURPOSE: To evaluate the role of simultaneous hybrid PET/MR imaging and to correlate metabolic PET data with morpho-functional parameters derived by MRI in patients with head-neck cancer. METHODS: Forty-four patients, with histologically confirmed head and neck malignancy (22 primary tumors and 22 follow-up) were studied. Patients initially received a clinical exam and endoscopy with direct biopsy. Next patients underwent whole body PET/CT followed by PET/MR of the head/neck region. PET and MRI studies were separately evaluated by two blinded groups (both included one radiologist and one nuclear physician) in order to define the presence or absence of lesions/recurrences. Regions of interest (ROIs) analysis was conducted on the primary lesion at the level of maximum size on metabolic (SUV and MTV), diffusion (ADC) and perfusion (K(trans), Ve, kep and iAUC) parameters. RESULTS: PET/MR examinations were successfully performed on all 44 patients. Agreement between the two blinded groups was found in anatomic allocation of lesions by PET/MR (Primary tumors: Cohen's kappa 0.93; FOLLOW-UP: Cohen's kappa 0.89). There was a significant correlation between CT-SUV measures and MR (e.g., CT-SUV VOI vs. MR-SUV VOI: ρ=0.97, p<0.001 for the entire sample). There was also significant positive correlations between the ROI area, SUV measures, and the metabolic parameters (SUV and MTV) obtained during both PET/CT and PET/MR. A significant negative correlation was observed between ADC and K(trans) values in the primary tumors. In addition, a significant negative correlation existed between MR SUV and ADC in recurrent tumors. CONCLUSION: Our study demonstrates the feasibility of PET/MR imaging for primary tumors and recurrent tumors evaluations of head/neck malignant lesions. When assessing HNC, PET/MR allows simultaneous collection of multiparametric metabolic and functional data. This technique therefore allows for a more complete characterization of malignant lesions.

The impact of sexually abstaining groups on persistence of sexually transmitted infections in populations with ephemeral pair bonds.

Individuals often stop reproducing some time before they die. In this paper we compose and analyze a logistic two-sex population model in which individuals form pairs just to mate (i.e. pair bonds are ephemeral) and later move on to sexually abstaining groups. Using this model, we study the impact of sexually abstaining groups on persistence of a benign sexually transmitted infection (STI) in populations with such ephemeral pair bonds. We observe that the presence of sexually abstaining groups cannot prevent an STI from invasion or eliminate it when already present if the transition rates to the sexually abstaining groups are independent of the infection status of individuals (susceptible or infected). On the other hand, if they depend on that status, the presence of sexually abstaining groups can prevent an STI from invasion or eliminate it when present. Specifically, in the simple case of sex-independent vital parameters, this happens if the transition rate of the infected individuals to the sexually abstaining group is higher than the transition rate of the susceptible ones. These results contrast the earlier results based on assuming long-term, stable pair bonds, in which case one is capable of preventing or eliminating the disease with the same isolation rate for the susceptible and infected individuals.

Amino acid composition of two peptides purified from mitochondrial calf liver DNA.

In this research the amino acidic composition of a peptide fraction from mitochondrial DNA has been determined, using HPLC and the fingerprinting technique. This peptide fraction has been shown to be composed of two sub-fractions with different reactivity to ninhydrin, and thus supplied with several N-substitute groups. The composition of the first fraction is Gln, Glu, Pro, Leu. The second fraction composition is Pro, Glu or Gln, Asp or Asn, Ser.

Effect of a peptide fraction extracted from mitochondrial DNA on rat liver cell viability.

The authors verified the effect of a peptidic fraction from mitochondrial DNA on liver cell cultures. Primary cultures treated with the mitochondrial peptidic fraction (final concentration 0.025 O.D./ml) showed a higher viability after 48 hours with respect to cultures without mitochondrial peptidic fraction (p < 0.05). The results indicate a probable action of the mitochondrial peptidic fraction on liver cell viability.

[Computed tomography in the follow-up of patients nephrectomized for adenocarcinoma]. / La tomografia computerizzata nel controllo dei pazienti nefrectomizzati per adenocarcinoma.

A retrospective study was carried out of 159 CT examinations acquired in 64 patients who underwent unilateral nephrectomy for renal-cell carcinoma (34 in the left-hand side and 30 in the right-hand side). Thirty-nine patients were examined twice in the three years following nephrectomy; 25 were examined three or more times over a 5-year period after nephrectomy. Acute or chronic inflammatory disease was demonstrated in 6 patients (4 abscesses were detected by means of clinico-radiologic signs and 2 by means of cytology after CT-guided needle biopsy). Twenty patients had local recurrences 2-7 cm phi: in 17 of them the diagnosis was confirmed by CT-guided percutaneous FNAB; 15 patients had liver metastases, in 3 of them associated with local recurrences; 26 patients were free of both local recurrences and distant metastases. The authors analyze the value of CT in the definition of post-nephrectomy anatomic alterations, in the early detection and staging of local recurrences, and in the differentiation between postoperative fibrosis and complications. Moreover, the value is stressed of CT-guided FNAB of suspicious lesions. Our study suggests the value of a methodical CT follow-up of asymptomatic post-nephrectomy patients. CT immediately after surgery is also recommended to serve as a baseline reference for subsequent examinations. In our series, CT was accurate in the early detection of both local recurrences and distant solitary metastases.

[Magnetic resonance in the diagnosis and follow-up of soft-tissue sarcomas]. / La Risonanza Magnetica nella diagnosi e nel follow-up dei sarcomi dei tessuti molli.

The authors analyze the advantages of MR imaging in the detection, staging and follow-up of malignant soft-tissue sarcomas. The role of MR imaging is retrospectively evaluated in 34 patients (16 men and 18 women) ranging in age from 3 to 82 years (mean: 38); 19 of them had a primary neoplasm, while the extant 15 patients were examined after surgery, and residual or recurrent tumors were present. Ten examinations were performed on an 0.5 T imager (CGR Magniscan 5000), and 27 were obtained with a 1.5 T system (Magnetom 42 SP Siemens). In all cases T1 and T2 sequences were acquired; in 3 patients T1-weighted sequences were performed after Gd-DTPA administration. In the 19 patients with primary tumors pathologic specimens were obtained. The value of MR imaging in the evaluation and characterization of soft-tissue sarcomas and its capabilities in detecting neurovascular encasement and bone involvement are discussed. Post-Gd-DTPA scans may help in the differentiation of necrotic areas from active tumors. MR diagnostic criteria of malignancy, including tissue heterogeneity and irregular margins, were not fulfilled in 3 of the studied cases.