Helical Computed Tomography Scans Research Articles

Dosimetric and geometric evaluation of a hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

For prostate cancer patients, online image-guided (IG) radiotherapy has been widely used in clinic to correct the translational inter-fractional motion at each treatment fraction. For uncertainties that cannot be corrected online, such as rotation and deformation of the target volume, margins are still required to be added to the clinical target volume (CTV) for the treatment planning. Offline adaptive radiotherapy has been implemented to optimize the treatment for each individual patient based on the measurements at early stages of treatment process. It has been shown that offline adaptive radiotherapy can effectively reduce the required margin. Recently a hybrid strategy of offline adaptive replanning and online IG was proposed and the geometric evaluation was performed. It was found that the planning margins can further be reduced by 1–2 mm compared to online IG only strategy. The purpose of this study was to investigate the dosimetric benefits of such a hybrid strategy on the target and organs at risk. A total of 420 repeated helical computed tomography scans from 28 patients were included in the study. Both low-risk patients (LRP, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles, SV) were included in the simulation. Two registration methods, based on center-of-mass shift of prostate only and prostate plus SV, were performed for IRP. The intensity-modulated radiotherapy was used in the simulation. Criteria on both cumulative and fractional doses were evaluated. Furthermore, the geometric evaluation was extended to investigate the optimal number of fractions necessary to construct the internal target volume (ITV) for the hybrid strategy. The dosimetric margin improvement was smaller than its geometric counterpart and was in the range of 0–1 mm. The optimal number of fractions necessary for the ITV construction is 2 for LRPs and 3–4 for IRPs in a hypofractionation protocol. A new cumulative index of target volume was proposed for the evaluation of adaptive radiotherapy strategies, and it was found that it had the advantages over other indices in evaluating different adaptive radiotherapy strategies.

Transcatheter embolization of a renal artery pseudoaneurysm after open partial nephrectomy

Twelve days after an open partial nephrectomy, a 31-year-old man was re-admitted urgently for acute lumbar pain. An emergent helical computed tomography scan with intravenous contrast revealed a 3-cm renal artery pseudoaneurysm at the site of the partial nephrectomy, which was responsible for a large perirenal hematoma. Transarterial hyperselective embolization successfully occluded the pseudoaneurysm with less than 1 mL of N-butyl-2-cyanoacrylate, an embolizing agent less costly than coils. The kidney parenchyma was fully preserved.

Short-term results of a randomized trial examining timing of carotid endarterectomy in patients with severe asymptomatic unilateral carotid stenosis undergoing coronary artery bypass grafting

This study evaluated the timing of carotid endarterectomy (CEA) in the prevention of stroke in patients with asymptomatic carotid stenosis >70% receiving a coronary artery bypass graft (CABG). From January 2004 to December 2009, 185 patients with unilateral asymptomatic carotid artery stenosis >70%, candidates for CABG, were randomized into two groups. In group A, 94 patients received a CABG with previous or simultaneous CEA. In group B, 91 patients underwent CABG, followed by CEA. All patients underwent preoperative helical computed tomography scans, excluding significant atheroma of the ascending aorta or aortic arch. Baseline characteristics of the patients, type of coronary artery lesion, and preoperative myocardial function were comparable in the two groups. In group A, all patients underwent CEA under general anesthesia with the systematic use of a carotid shunt, and 79 patients had a combined procedure and 15 underwent CEA a few days before CABG. In group B, all patients underwent CEA, 1 to 3 months after CABG, also under general anesthesia and with systematic carotid shunting. Two patients (one in each group) died of cardiac failure in the postoperative period. Operative mortality was 1.0% in group A and 1.1% in group B (P = .98). No strokes occurred in group A vs seven ipsilateral ischemic strokes in group B, including three immediate postoperative strokes and four late strokes, at 39, 50, 58, and 66 days, after CABG. These late strokes occurred in patients for whom CEA was further delayed due to an incomplete sternal wound healing or because of completion of a cardiac rehabilitation program. The 90-day stroke and death rate was 1.0% (one of 94) in group A and 8.8% (eight of 91) in group B (odds ratio [OR], 0.11; 95% confidence interval [CI], 0.01-0.91; P = .02). Logistic regression analysis showed that only delayed CEA (OR, 14.2; 95% CI, 1.32-152.0; P = .03) and duration of cardiopulmonary bypass (OR, 1.06; 95% CI, 1.02-1.11; P = .004) reliably predicted stroke or death at 90 days. This study suggests that previous or simultaneous CEA in patients with unilateral severe asymptomatic carotid stenosis undergoing CABG could prevent stroke better than delayed CEA, without increasing the overall surgical risk.

SU‐E‐J‐175: An Analysis of Localization Methods for SRS Using CBCT

Purpose: To evaluate multiple methods of localization for stereotactic radiosurgery (SRS) for spatial accuracy and time required for each procedure. Methods: Multiple phantoms were imaged using a helical diagnostic computed tomography (CT) scanner (Toshiba™ Aquilion) and a linear accelerator mounted cone‐beam computed tomography (CBCT). Scans (for both machines) were acquired with a matrix of 512×512 at a field of view of 340 mm. A Varian Medical Systems™ absolute position phantom, in‐house created uniformity phantom, LUCY™ phantom, and Catphan phantom were each imaged to compare spatial homogeneity, linearity, spatial resolution, contrast, and uniformity. A final test of localization accuracy was completed by localizing a phantom using three different Methods: headring localization using helical CT, headring localization using CBCT, and “anatomical” localization using on‐board CBCT. Results: Average spatial localization errors from absolute phantom spheres were similar for the helical CT scanner (∼0.37 mm) compared with the on‐board CBCT (∼0.35 mm). R2 values for a line fit to the spatial position of the rods in the uniformity phantom scanned with CBCT were > 0.99. Spatial resolution of CBCT and CT were found to be similar using the CTP528 insert of the Catphan phantom (0.071 line pairs/cm). Spatial accuracy of localization by headring for CT and CBCT were similar but “anatomical” localization with CBCT may be less consistent. Conclusions: The spatial accuracy and linearity of CBCT may be adequate for stereotactic localization using a headring for SRS. Loss of low contrast resolution in CBCT may affect localization and position by CBCT alone. Headring localization using CBCT results in overall time savings without significant loss of spatial information. Localization by CBCT alone may result in increased spatial inaccuracies due to loss of contrast and potential MV radiation and on‐board imager isocenter mismatches.

Computed Tomographic Analysis of Outer Calvarial Thickness for Osseointegrated Bone-Anchored Hearing System Insertion

Osseointegrated bone-anchored hearing systems (BAHSs) are a useful tool in auditory rehabilitation for single-sided deafness and conductive/mixed hearing loss. They rely on adequate osseointegration of titanium implants, which can be limited by calvarial thickness. This study examines adult computed tomographic (CT) temporal bone normative data for calvarial thickness in the areas commonly recommended for BAHS insertion and identifies hazards that may compromise the osseointegration process. Prospective analysis of 100 consecutive adult helical CT scans. Calvarial thickness was measured in axial and coronal planes 5.5 cm posterior to the superior external auditory canal at 6 vertical points (EAC, +1 cm, +2 cm, +3 cm, +4 cm, and +5 cm). Other parameters measured include temporal bone pneumatization and the presence of suture lines, bone marrow, and vascular structures. A total of 195 temporal bones were examined in 100 patients. Mean patient age was 60.9 years, of whom 54.4% were men and 45.6% were women. Mean calvarial thickness was greatest at +1 cm above the EAC level (6.3 mm) and thinnest at +4 cm (5.1 mm). Of temporal bones, 55% had at least 1 site thinner than 4 mm and 21% had at least 1 site thinner than 3 mm. Air cells and suture lines were more likely to be encountered within 2 cm above the EAC level, and marrow space is more likely to be encountered 3 to 4 cm above the EAC level. Selecting a position 3 to 4 cm above the level of the EAC is more likely to result in dural exposure for a 3-mm BAHS abutment, especially in men. Selecting a position near the level of the EAC provides thicker bone, but the surgeon is more likely to encounter suture line or enter mastoid air cells. Preoperative CT imaging may be a useful tool in evaluating calvarial thickness and hazards when planning BAHS insertion in the adult population.

Evaluation of triphasic helical computed tomography of the kidneys in clinically normal dogs

To determine computed tomography (CT) delay times by use of a sequential scan and identify the normal enhancement pattern in each phase of a triphasic CT scan of the kidneys in dogs. 14 healthy Beagles. A sequential CT scan was used for investigating delay time, and a triphasic helical CT scan was used for identifying the normal enhancement pattern and determining Hounsfield unit values in the kidneys of dogs. In the cine scan (single-slice dynamic scan), the optimal delay times were 10 seconds in the corticomedullary phase and 44 seconds in the nephrographic phase, after contrast medium injection. By use of triphasic CT images, Hounsfield unit values were acquired in each phase. Triphasic CT of the kidneys in clinically normal dogs was established by acquisition of delay times in a cine scan and may become an important imaging modality in the diagnosis of renal diseases and in treatment planning in dogs.

Estimation of intrathoracic arterial diameter by means of computed tomographic angiography in Hispaniolan Amazon parrots

To establish a computed tomography (CT)-angiography protocol and measure the diameters of major arteries in parrots. 13 Hispaniolan Amazon parrots (Amazona ventralis). 16-slice CT scanning was used to measure the apparent diameter of the ascending aorta, abdominal aorta, pulmonary arteries, and brachiocephalic trunk. Before scanning, all birds underwent ECG and echocardiographic assessment and were considered free of detectable cardiovascular diseases. Each bird was anesthetized, and a precontrast helical CT scan was performed. Peak aortic enhancement was established with a test bolus technique via dynamic axial CT scan over a predetermined single slice. An additional bolus of contrast medium was then injected, and a helical CT-angiography scan was performed immediately afterward. Arterial diameter measurements were obtained by 2 observers via various windows before and after injection, and intra- and interobserver agreement was assessed. Reference limits were determined for arterial diameter measurements before and after contrast medium administration in pulmonary, mediastinal, and manual angiography windows. Ratios of vertebral body diameter to keel length were also calculated. Intraobserver agreement was high (concordance correlation coefficients ≥ 0.95); interobserver agreement was medium to high (intraclass correlation coefficients ≥ 0.65). CT-angiography was safe and is of potential diagnostic value in parrots. We recommend performing the angiography immediately after IV injection of 3 mL of iohexol/kg. Arterial diameter measurements at the described locations were reliable.

A methodology for direct quantification of over‐ranging length in helical computed tomography with real‐time dosimetry

In helical computed tomography (CT), reconstruction information from volumes adjacent to the clinical volume of interest (VOI) is required for proper reconstruction. Previous studies have relied upon either operator console readings or indirect extrapolation of measurements in order to determine the over‐ranging length of a scan.( 1 – 5 ) This paper presents a methodology for the direct quantification of over‐ranging dose contributions using real‐time dosimetry. A Siemens SOMATOM Sensation 16 multislice helical CT scanner is used with a novel real‐time “point” fiber‐optic dosimeter system with 10 ms temporal resolution to measure over‐ranging length, which is also expressed in dose‐length‐product (DLP). (6) Film was used to benchmark the exact length of over‐ranging. Over‐ranging length varied from 4.38 cm at pitch of 0.5 to 6.72 cm at a pitch of 1.5, which corresponds to DLP of 131 to 202 mGy‐cm. The dose‐extrapolation method of Van der Molen et al. yielded results within 3%, while the console reading method of Tzedakis et al.( 2 , 4 ) yielded consistently larger over‐ranging lengths. From film measurements, it was determined that Tzedakis et al.( 2 , 4 ) overestimated over‐ranging lengths by one‐half of beam collimation width. Over‐ranging length measured as a function of reconstruction slice thicknesses produced two linear regions similar to previous publications.( 1 – 4 ) Over‐ranging is quantified with both absolute length and DLP, which contributes about 60 mGy‐cm or about 10% of DLP for a routine abdominal scan. This paper presents a direct physical measurement of over‐ranging length within 10% of previous methodologies.( 1 – 4 ) Current uncertainties are less than 1%, in comparison with 5% in other methodologies. Clinical implantation can be increased by using only one dosimeter if codependence with console readings is acceptable, with an uncertainty of 1.1% This methodology will be applied to different vendors, models, and postprocessing methods – which have been shown to produce over‐ranging lengths differing by 125%. (4) PACS number: 87.57.qp

Computer-based analysis with three-dimensional imaging constructed from fine-slice computed tomography scan of supracricoid laryngectomy with cricohyoidoepiglottopexy: report of two cases

Supracricoid laryngectomy with cricohyoidoepiglottopexy is an organ-preserving surgical technique used to treat laryngeal cancer. This procedure resects the vocal folds; however, it is unclear how the sound source and airway morphology are involved in phonation through the post-operative neoglottis. Multidetector helical computed tomography scanning was performed on two patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy. The cricoid and arytenoid cartilages and the airway were visualised using three-dimensional images. The mobility of the arytenoid cartilages was well preserved in the one patient with bilateral arytenoids, and in the other patient with only one arytenoid remaining. Two types of airway configuration were observed during phonation: one patient had a single stream airway, while the other had a combination of several streams. In the patient with only one arytenoid remaining, the preserved arytenoid tended to be rotated excessively inward. Therefore, phonation may have also occurred in various airways followed by mucosal vibration, which may be a sound source.

Surgical Anatomy of Urogenital Diaphragm and Course of Its Vessels in Exstrophy-Epispadias

To report the surgical anatomy of the muscles of the urogenital diaphragm and the pattern of its vessels in the classic exstrophy bladder and incontinent epispadias. A total of 11 patients, 9 with unoperated classic exstrophy and 2 with incontinent epispadias, who were >5 years old at presentation, were selected for the present study. Magnetic resonance imaging of the pelvis was performed using a 3.0 T magnetic resonance imaging scanner and an 8-channel coil. Computed tomography was performed for 5 patients using a multidetector row helical computed tomography scanner. Angiograms of the vessels of the urogenital diaphragm were also obtained using magnetic resonance imaging and computed tomography. A central perineal body was seen in all the patients, with attachment of the bulbospongiosus anteriorly, superficial transverse perinei laterally, and anal sphincter posteriorly. At the root of corpora, the ischiocavernosus muscle was also seen. The triangle among the ischiocavernosus, bulbospongiosus, and superficial transverse perinei muscle was accentuated and contained the perineal artery, indirectly indicating the course of the perineal nerve. The dorsal penile artery was nearer to the posterior edge of the ischiopubic ramus, before coursing on the lateral aspect of the anterior segment of the corpora. The deep transverse perinei muscle and laid open external urethral sphincter were also seen in the proximal planes of the urogenital diaphragm. First, all the muscles of the urogenital diaphragm, including the external urethral sphincter, were present in the exstrophy bladder. Second, the perineal artery and its sphincteric branches were in the triangular space between the ischiocavernosus, bulbospongiosus, and superficial transverse perinei muscle. Finally, the dorsal penile artery ran along the inner edge of the ischiopubic ramus before lying on lateral aspect of the corpora.

To study tumor motion and planning target volume margins using four dimensional computed tomography for cancer of the thorax and abdomen regions

In this study, four dimensional computed tomography (4DCT) scanning was performed during free breathing on a 16-slice Positron emission tomography PET /computed tomography (CT) for abdomen and thoracic patients. Images were sorted into 10 phases based on the temporal correlation between surface motion and data acquisition with an Advantage Workstation. Gross tumor volume gross tumor volume (GTV) s were manually contoured on all 10 phases of the 4DCT scan. GTVs in the multiple CT phases were called GTV4D. GTV4D plus an isotropic margin of 1.0 cm was called CTV4D. Two sets of planning target volume (PTV) 4D (PTV4D) were derived from the CTV4D, i.e. PTV4D2cm = CTV4D plus 1 cm setup margin (SM) and 1 cm internal margin (IM) and PTV4D1.5cm = CTV4D plus 1 cm SM and 0.5cm IM. PTV3D was derived from a CTV3D of the helical CT scan plus conventional margins of 2 cm. PTVgated was generated only selecting three CT phases, with a total margin of 1.5 cm. All four volumes were compared. To quantify the extent of the motion, we selected the two phases where the tumor exhibited the greatest range of motion. We also studied the effect of different PTV volumes on dose to the surrounding critical structures. Volume of CTV4D was greater than that of CTV3D. We found, on an average, a reduction of 14% volume of PTV4D1.5cm as compared with PTV3D and reduction of 10% volume of PTVgated as compared with PTV4D1.5cm. We found that 2 cm of margin was inadequate if true motion of tumor was not known. We observed greater sparing of critical structures for PTVs drawn taking into account the tumor motion.

Three-Phase Helical Computed Tomographic Findings of Hepatic Neuroendocrine Tumors

To evaluate 3-phase helical computed tomographic (CT) findings of hepatic neuroendocrine tumors and to correlate them with pathologic diagnoses based on the revised World Health Organization classification. Over a 14-year period, we collected 38 patients with pathologically proven neuroendocrine tumors of the liver, either primary or metastatic, who had 3-phase helical CT scans. CT findings were evaluated for the morphologic and enhancement patterns (ie, hepatocellular carcinomalike, cholangiocarcinomalike, and combined patterns), and correlated those with pathologic diagnoses. The morphologic patterns were variable regardless of the pathologic diagnoses, except necrosis (P = 0.024). For the enhancement pattern, almost half of the tumors showed hepatocellular carcinomalike pattern, and the other half showed cholangiocarcinomalike or combined patterns, without correlation between the enhancement pattern and pathologic diagnoses (P = 0.402). The CT features of hepatic neuroendocrine tumors were variable and did not correlate with their pathologic diagnoses. However, hepatic neuroendocrine tumors frequently show hepatocellular carcinomalike arterial enhancement, and often show cholangiocarcinomalike delayed enhancement.

Accuracy of helical computed tomography in the detection of pulmonary colorectal metastases

This study assessed the sensitivity of helical computed tomography in the detection of pulmonary metastases in patients with colorectal cancer and the role of video-assisted thoracoscopic surgery in patients with pulmonary metastases. A total of 120 operations for pulmonary metastases were performed in 91 patients with colorectal cancer. All patients received an open thoracotomy that allowed full operative inspection and palpation. Clinical data, including the size and number of pulmonary metastasis, were retrospectively collected. The difference in the number of pulmonary metastases as determined by computed tomography scan and surgical findings was determined and analyzed. Operative findings were consistent with the preoperative computed tomography scan reports in 64 of the 120 operations (53.3%). In 32 operations (26.7%), additional metastatic tumors were identified at open thoracotomy. The sensitivity of helical computed tomography in the detection of colorectal cancer metastatic lesions ranged from 35.5% to 95.5%. Unilateral solitary lesion demonstrated on computed tomography scan was an independent factor for the prediction of additional metastatic lesions (P = .023). The sensitivity of helical computed tomography scan in the detection of pulmonary metastases can reach 95.5% in patients with colorectal cancer with a solitary metastatic lesion. A unilateral solitary lesion demonstrated on preoperative computed tomography scan is an independent factor for prediction of additional metastatic lesions. If feasible, video-assisted thoracoscopic surgery may be justified in patients with colorectal cancer with solitary pulmonary metastases.

Preoperative staging of renal cell carcinoma using triphasic helical computed tomography

ObjectiveTo determine if staging of renal cell carcinoma (RCC) can be predicted from preoperative triphasic helical computed tomography (CT) findings. Patients and methodsWe reviewed the triphasic helical CT scans of 48 consecutive patients with pathologic diagnosis RCCs. All tumors were staged according to the 2002 version of TNM staging system. The preoperative radiologic staging was compared with postoperative pathologic staging. Agreement between the two staging systems was determined using the kappa test. ResultsComparison between triphasic helical CT staging and pathologic staging showed harmony in all lesions in stage T1a, and T1b. Triphasic helical CT over diagnosed two cases of stage T1b regarded as stage T3a while agreement was noted in all cases of stage T2. Harmony was noted between triphasic helical CT and pathologic staging in two lesions stage T3a, four lesions in stage T3b, and two lesions stage T4. The agreement between triphasic helical CT and pathologic T stages was perfect (K=0.941). Forty-two cases were staged N0, one case was N1, and five cases were staged N2 by triphasic CT. Three cases were over staged, and six cases were under staged while, 39 were correctly N staged. The agreement between triphasic helical CT and pathologic N staging was poor (K=0.33). ConclusionThe agreement between the preoperative triphasic helical CT staging and postoperative pathologic T staging is perfect, while agreement in N stages is poor. So T staging of RCC can be predicted from triphasic helical CT findings while N staging cannot be predicted preoperatively.

Imaging Requirements in the Practice of Pulmonary Metastasectomy

The primary imaging modality for the detection of pulmonary metastases is computed tomography (CT). Ideally, a helical CT scan with 3- to 5-mm reconstruction thickness or a volumetric thin section scanning should be performed within 4 weeks of pulmonary metastasectomy. A period of observation to see whether further metastases develop does not seem to allow better patient selection. If positron emission tomography is available, it may identify the extrathoracic metastatic sites in 10 to 15% of patients. Despite helical CT scan, palpation identifies the metastases not detected by imaging in 20 to 25% of patients and remains the standard. No data define the optimal interval for follow-up surveillance imaging.

SU-GG-T-19 Automatic Contour Propagation between Planning Computed Tomography (CT) and Cone Beam CT (CBCT) Scan for In-Room Adaptive Planning: A Feasibility Study on Nasopharyngeal Cancer Patients

Purpose: The purpose of this study is to demonstrate the substancial equivalence of deformable registered planning CT images and propagated planning contours on CBCT dataset with replanning volume CT and manually adapted structures of interests. Method and Materials: The study includes two nasopharyngeal cancer patients, imaged with a helical mode CT scan before starting the therapy (CTsim). The patient also underwent CBCT scans on a Varian On-Board Imager (OBI) after 40Gy dose delivery and a re-planning CT scan (CTrepl). We performed a B-Spline intensity based deformable registration between CTsim and CBCT with the in-house software Plastimatch. The output deformation field was used to propagate the structures of interest on the CBCT volume. A rigid registration between CTrepl and CBCT was also necessary to obtain surrogate contours for the CBCT volume. The registered images were evaluated in terms of increment of Mutual Information(MI) and of mean overlap between the propagated structures by means of Dice coefficient (DSC). Results: The MI shared by the warped CTsim and CBCT in comparison with the MI shared by CTsim and CBCT before registration showed an increment of 35% and 33% for patient 1 and 2 respectively, quantitatively assessing the goodness of deformable registration as supposed after visual inspection. The rigid registration outputs showed residual anatomical discrepancies between the CTrepl and CBCT volumes. DSC value were well above 0.80 for all the structures of interests but right eye for patient 1, while difference in contouring, poor rigid registration and/or different image quality caused the DSC to be lower in most structures for patient 2. Conclusion: The developed algorithm is able to propagate contours to a CBCT dataset acquired either before or after a CTrepl. This method represents the first step towards a full in-room adaptation of a previously calculated plan.

Diagnosis of Necrotizing Soft Tissue Infections by Computed Tomography

In contrast to previous beliefs, we hypothesize that computed tomography (CT) scanning is sensitive and specific for the diagnosis of necrotizing soft tissue infections (NSTIs). Retrospective and prospective case series. Academic medical center. Patients who were clinically suspected of having NSTIs from January 1, 2003, through April 30, 2009, and who underwent imaging with a 16- or 64-section helical CT scanner were studied. The CT result was considered positive if inflamed and necrotic tissue with or without gas or fluid collections across tissue planes was found. The disease (NSTI) was considered present if surgical exploration revealed elements of infection and necrosis of the soft tissues and pathological analysis confirmed the findings. The disease was considered absent if surgical exploration and pathological analysis failed to identify any of these findings or the patient was successfully treated without surgical exploration. Sensitivity and specificity of CT for diagnosing NSTI. Of 67 patients with study inclusion criteria, 58 underwent surgical exploration, and NSTI was confirmed in 25 (43%). The remaining 42 patients had either nonnecrotizing infections during surgical exploration (n = 33) or were treated nonoperatively with successful resolution of the symptoms (n = 9). The sensitivity of CT to identify NSTI was 100%, specificity was 81%, positive predictive value was 76%, and negative predictive value was 100%. No differences were found in demographics, white blood cell count on admission, symptoms, or site of infection between those with a false- or true-positive CT result. A negative CT result reliably excludes the diagnosis of NSTI. A positive CT result correctly identifies the disease with a high likelihood.

Use of multi‐detector computed tomographic angiography in the diagnosis of a parapharyngeal aneurysm in a 6‐week‐old foal

Multidetector-row computed tomographic contrast angiography (MDCTA) is routinely employed to investigate vascular masses in human patients but, to date, the use of this technique to investigate an aneurysmal mass has not been reported in an equine case. The potential of MDCTA to investigate a right-sided parapharyngeal mass in a 6-week-old Thoroughbred foal was therefore investigated. A 4-slice helical computed tomography scanner was used on a superficial, firm, ovoid mass yielding arterial blood on fine needle aspiration. MDCTA enabled identification of the vessels involved thus assisting in forming a diagnosis based on the morphology of the lesion and aided surgical planning. Histology confirmed the presence of mural thrombus and calcification within the smooth muscle wall consistent with a true aneurysm. MDCTA provided additional information to conventional imaging in this case of vascular masses of the head and neck. The technique therefore has the potential to improve diagnosis and assist in the management of such lesions.

Lung lobar volume in patients with chronic interstitial pneumonia

We measured lung lobar volume by using helical computed tomography (HCT) in 23 patients with idiopathic interstitial pneumonia (IIP), 7 patients with chronic interstitial pneumonia associated with collagen vascular disease (CVD-IP), and 5 healthy volunteers. HCT scanning was done at the maximal inspiratory level and the resting end-expiratory level. To measure lung lobar volume, we traced the lobar margin on HCT images with a digitizer and calculated the lobar volume with a personal computer. The lower lobar volume and several factors influencing it in chronic interstitial pneumonia were studied. At the maximal inspiratory level, the lower lobar volume as a percent of the whole lung volume was 46.8 +/- 4.13% (mean +/- SD) in the volunteers, 39.5 +/- 6.19% in the patients with IIP, and 27.7 +/- 7.86% in the patients with CVD-IP. The lower lobar volumes in the patients were significantly lower than in the volunteers. Patients with IIP in whom autoantibody tests were positive had lower lobar volumes that were very low and were similar to those of patients with CVD-IP. These data suggest that collagen vascular disease may develop in patients with interstitial pneumonia. The patients with IIP who had emphysematous changes on the CT scans had smaller decreases in total lung capacity and lower ratios of forced expiratory volume in one second to forced vital capacity than did those who had no emphysematous changes, those two groups did not differ in the ratio of lower lobar volume to whole lung volume. This suggests that emphysematous change is not factor influencing lower lobar volume in patients with chronic interstitial pneumonia. We conclude that chronic interstitial pneumonia together with very low values for lower lobar volume may be a pulmonary manifestation of collagen vascular disease.

乳腺内視鏡手術と3D-CT乳腺リンパ管造影＜その2＞3D-CT乳腺リンパ管造影によるセンチネルリンパ節生検

Background: I have studied endoscopic surgery for breast diseases and 3-dimensional (3D) computed tomographic (CT) lymphography for sentinel node (SN) biopsy. In this second in a series of reports, I explain the techniques of 3D-CT lymphography. 3D-CT lymphography can show the detailed lymphatic flow from the breast tumor toward the SNs and the exact local relation between axillary lymph nodes. I have developed this 3D image-processing system to more precisely depict the anatomical structures of the mammary lymphovascular system. This system allows us to systematically collect axillary lymph nodes, including SNs. Methods: 3D-CT lymphography was performed to mark SNs on the skin on the day before surgery. Above the tumor and near the areola, 2ml of Iopamiron 300 was injected subcutaneously. Sixteen-channel multidetector-row helical CT scan images were obtained 1 minute after injection to detect SNs, and after 3 and 5 minutes to observe lymph flow into the venous angle. The scan images were reconstructed to produce 3D images. SN biopsy was performed with the dye-staining method and endoscopy. Results: 3D-CT lymphography accurately showed lymphatic flow from the tumor to SNs. We classified the relationship between the lymph ducts and the drained SNs into 4 patterns. Following up 3 and 5 minutes after injection of the contrast agent, we can follow the lymph ducts beyond the SN into the second and third nodes toward the venous angle with the complex plexus. The figure of the axillary nodes shows 5 beads-like grouped nodes. 3D-CT lymphography can also recognize the metastatic patterns of the enhanced lymph node. These patterns will predict the metastasis before SN biopsy. 3D-CT lymphography can also be used to detect lymph flow from the arm to avoid harming the arm lymph channel during axillary node dissection and SN biopsy. Conclusions: With 3D-CT lymphography, we can more accurately and precisely recognize lymph flow and the positional relations of SN and axillary nodes to surrounding anatomical structures.