On the delineation of the gross tumor volume and clinical target volume for head and neck squamous cell carcinomas.

Gross tumor volume (GTV) and clinical target volume (CTV) delineation on planning computed tomography (pICT) for head and neck squamous cell carcinomas can be troublesome. We highlight the factors which can be crucial for the radiation oncologist in delineating GTV and CTV on pICT and provide some pratical solutions. Regarding GTV, uncertainties are correlated with transfer of information collected by physical examination and diagnostic radiology to pICT. Moreover, reproducibility of delineation can also be highly variable, particularly when diagnostic imaging quality and pICT quality are poor. Once the prescription has been made, clinical target volume identification on pICT is rarely straightforward. Whereas there are some data about the location of major lymph node stations of the neck, there are no reported guidelines on how to draw subclinical extention of primary head and neck tumors on pICT. Such volumes can be derived from those currently included in simulator films or from those addressed by the surgeon. Some examples are provided. A particular situation is represented by the adjuvant setting, when the primary tumor is removed (by surgery) or reduced (by chemotherapy). In conclusion, this paper shows some major problems associated with identification of GTV and CTV on pICT. Apart from selected cases, the use of pICT for target volume delineation (and thus for field shaping) for head and neck squamous cell carcinoma is still to be considered investigational.

Management of the neck after alternating chemoradiotherapy for advanced head and neck cancer.

BACKGROUND: To investigate neck control probability and the value of nodal response at completion of alternating chemoradiotherapy, a group of 43 patients was reviewed. METHODS: Patients were treated with 60 Gy alternated with four cycles of cisplatin and fluorouracil. All patients had lymph nodes positive for squamous cell carcinoma from various primary sites, underwent computed tomography (CT) for staging and evaluation of response, and were treated at a single institution. Patients with bilateral lymph nodes (N2c) were further staged according to the side of dominant neck disease. RESULTS: After chemoradiotherapy alone, 2-year neck control probabilities (NCP) are 86+/-13%, 58+/-10%, and 0 for N1, N2a/b, and N3 neck stages, respectively (p = .038). Two-year NCP for 25 complete responders is 85+/-8%, whereas, at the same time interval, it is 17+/-9% for 18 partial responses (p<.0001). Within patients with N1-2a/b neck disease, 21 complete responders had a 2-year NCP of 92+/-8%. Five (11%) heminecks in four patients developed severe (Radiation Therapy Oncology Group [RTOG] grade > 2) subcutaneous late reactions. CONCLUSIONS: For patients with N1-2a/b neck disease, response at the end of treatment as evaluated by both physical exam and CT is a reliable criterion to select patients for complementary surgery even after chemoradiotherapy. For N3 disease, planned neck dissection regardless of response seems warranted.

Assessment of the CO2 response by means of non diffusible contrast media and angio-CT in patients with cluster headache.

We analyzed the possibility of assessing functional vasomotor changes by means of Arm-Brain Circulation Time (rABCT) and Vascular volume images (Vv) obtained with Angio-CT, in basal condition and following CO2 inhalation, in a sample of 48 patients with cluster headache. CO2 inhalation resulted in the appearance of local changes, which were detected in 28 regions. Analysis by indicator images of Vv-dependent rABCT distribution showed two main patterns: abnormal rABCT mostly evident at the smallest Vv pixels and abnormal rABCT dependent on abnormal Vv distribution. The former pattern was linked to abnormality at the circle of Willis; the latter to abnormal local vasomotor responses. Patients with cluster headache showed both patterns, which prompted us to conclude for the presence of low-degree stenosis in carotid arteries and vasomotor instability in peripheral brain vessels.

Assessment of regional cerebral blood flow images with non-diffusible contrast media and angio-CT. Comparison with Xe-CT.

We derived rCBF (ND-rCBF) images using non-diffusible contrast agent time-density curves obtained by monitoring the first pass with an angio-CT sequence. An appropriate elaboration of the sequence of the images led to the generation of vascular volume (Vv) and regional Arm-Brain circulation time images (rABCT). ND-rCBF was obtained by dividing the Vv image by the rABCT image after having rendered them suitable for such an operation. Regional cerebral vascular volume (rCBF) was assessed by standardizing Vv values with blood contrast concentration and intracranial circulation time (rICT) by subtracting from the rABCT image the inflow mean time, assessed as the lowest rABCT value of the slice. The ND-rCBF images were qualitatively fairly well comparable with synchronous rCBF (D-rCBF) images obtained with the Xe-CT technique. However quantitation of the values by ROI use gave different results, the ND-rCBF image showing considerably higher values. Using indicator images to analyse the rCBF values at different levels of rCBV and rICT, it was shown that there was a significant relation between the two ND-rCBF and D-rCBF values in the 70-80% pixels with higher rABCT and lower rCBF values.

Functional circulation images by angio-CT in the assessment of small deep cerebral infarctions.

We analyzed circulation time (rABCT) and vascular volume density images obtained by angio-computerized tomography (angio-CT) in 63 patients with small deep cerebral infarctions. Abnormalities in the rABCT image were found in 88% of the patients and in the vascular volume image in 48%. Two groups with different clinical pictures were picked out by rABCT changes: one with major-vessel involvement, the other with small-vessel involvement. The perfusional changes found were mainly due to altered vascular canalization rather than to altered vasomotility. The hemodynamic theory could explain the spatial relations between perfusion changes and CT hypodense areas without needing assumptions linking blood flow and metabolism.

Functional perfusion and blood-brain barrier permeability images in the diagnosis of cerebral tumors by Angio CT.

We performed rapid sequential CT scanning following iv injection of a bolus of contrast medium and generated three functional images relating to intravascular circulation time (rABCT), vascular volume (Vv) density and blood-brain barrier (BBB) unidirectional constant uptake rate (Ki), respectively. This was accomplished by calculating the first mathematical moment of the monitored time-density curves about the injection time and from the multiple time graph analysis described by Patlack and co-workers. A satisfactory resolution was achieved, allowing separate appreciation of changes in rABCT both in large vessels and in tissue small vessels. Combined evaluation of rABCT and Vv images allowed us to differentiate between tumors.

Functional circulation time images in the diagnosis of cerebral lesions by angio CT.

An application of angio CT as an adjunct to contrast enhancement evaluation of cerebral lesions is presented. We performed rapid sequential scanning following intravenous bolus injection of an iodinated contrast medium, analyzed the time contrast curves and generated a functional circulation time image. This was accomplished by calculating on a pixel-by-pixel basis the first mathematical moment of the monitored time-density curves about injection time which corresponds to regional arm brain circulation time (rABCT). This method increased the rate of detection of cerebral lesions by contrast enhancement from 30 to 90%.

Assessment of 99mTc-HM-PAO parameters with SPECT for improved evaluation of blood flow in cerebral lesions.

A method for investigating the linearity between blood flow and distribution of 99mTc-HM-PAO uptake in patients undergoing single photon emission computed tomography (SPECT) is presented. This method, based on particular elaboration techniques of sequential multiple acquisitions, provides a local index: cumulative transit time (CTT) related to all factors, other than blood flow, affecting 99mTc-HM-PAO uptake. Because a correct qualitative blood flow estimation is based on the uniformity of the above factors, the occurrence of a change of this index indicates a nonlinear relation between blood flow and 99mTc-HM-PAO uptake distributions. It was shown that although linearity between blood flow and 99mTc-HM-PAO uptake may be questionable, a qualitative assessment of blood flow was correct in 100% of ischemic patients. In nonischemic patients this percentage fell to 60%.

Vigabatrin in complex partial seizures: a long-term study.

The efficacy and safety of oral vigabatrin (VGB) as add-on therapy in the long-term treatment of poorly controlled epilepsy were evaluated in 19 patients with complex partial seizures, either with or without secondary generalization. The study was run with a single-blind, placebo-controlled, crossover design, and included 2 months of placebo and 13-15 months of treatment with VGB, at doses ranging from 1 to 4 g/day. Of the 14 patients who completed the trial, 2 were seizure free, in 5 seizure frequency dropped by more than 75% and in another 5 by more than 50% with respect to baseline. The decrease in seizure frequency in the group as a whole was significant at all observation points of the trial. Three patients were not entered into the long-term phase due to lack of improvement (an increase in seizure frequency was observed in one of them), and 2 were excluded later because improvement disappeared leading to unauthorized changes in comedication. Side effects were mild and never caused discontinuation of treatment. In conclusion, VGB showed a remarkable efficacy and safety in the long-term treatment of complex partial seizures.