Abstract: BACKGROUND AND PURPOSE: Flow voids within the cavernous sinuses and/or certain venous drainage on spin-echo MR imaging and time-of-flight (TOF) flow enhancement on MR angiography (MRA) have indicated high-velocity shunt flow and have been used for screening patients with dural arteriovenous fistulas (DAVFs) of the cavernous sinuses. In this investigation, the capabilities of 3D dynamic MRA as a flow-independent approach and those of conventional MR imaging techniques were compared with selective angiography for the diagnosis of DAVFs of the cavernous sinuses. MATERIALS AND METHODS: This retrospective study involved 18 patients with angiographically proved DAVFs of the cavernous sinuses and 12 control subjects. Sixteen partially overlapping sequential MR images were acquired on contrast-enhanced 3D dynamic MRA between the petrosal bone and the orbital roof. Two experienced observers blinded to the clinical data and results of angiography independently graded 3D dynamic MRA, fast spin-echo T2-weighted imaging (FSE T2WI), and TOF MRA. RESULTS: The average area under the receiver operating characteristic curve values and interobserver kappa scores for the diagnosis of DAVFs on 3D dynamic MRA, FSE T2WI, and TOF MRA were 0.99, 0.89, and 0.95; and 0.92, 0.71, and 0.73, respectively. Those for the diagnosis of anterior, posterior, and retrograde cortical venous drainage on 3D dynamic MRA were 0.72, 0.95, and 0.81; and 0.56, 0.50, and 0.49, respectively. CONCLUSION: In this small series, screening 3D dynamic MRA directly demonstrates DAVFs of the cavernous sinuses and has improved diagnostic capability.
Abstract: BACKGROUND: We reviewed our experience to investigate the determinants of paraplegia/paraparesis after endovascular stent-graft repair of the thoracic aorta, to assess the influence of the artery of Adamkiewicz (ARM) detected by preoperative magnetic resonance angiography (MRA) and to identify patients at risk. METHODS: Over a 5-year period (March 2001-June 2006), 149 patients underwent elective endovascular stent-graft repair of the descending thoracic aorta. Patient demographics and perioperative factors relating to the endovascular procedure were evaluated by using univariate statistical analyses. To assess the influence of the ARM in the thoracolumbar region, patients in whom ARM was detected by preoperative MRA were divided into two groups: patients who had occlusion of the intercostal artery for ARM due to stent-graft (group A, n=33) and patients who had patency of the intercostal artery for ARM following stent-graft (group B, n=38). RESULTS: Five (3.6%) of the 144 patients had paraparesis/paraplegia. Two of these five patients had previously undergone operation for total arch replacement with elephant trunk and one had surgery for descending aortic repair. Univariate analyses identified only prior aortic surgery as a significant risk factor (p=0.04). Paraparesis/paraplegia rates were 10% (three patients) in group A and 0% in group B (p=0.09). CONCLUSION: Prior thoracic aortic replacement was found to be a significant predictor of spinal cord ischemia, and therefore vigilance is needed regarding occlusion of the intercostal artery for ARM detected prior to stent-graft repair.
Abstract: PURPOSE: To evaluate the efficacy of double-subtraction magnetic resonance angiography (MRA) (subtraction of the subtracted venous phase image from the subtracted arterial dominant phase image) for depicting the artery of Adamkiewicz and differentiating it from the drainage vein. MATERIALS AND METHODS: A total of 170 patients (123 men, 47 women; aged 17-84 years, mean = 67 years), with a thoracoabdominal vascular lesion underwent MRA for detection of the artery of Adamkiewicz. MRA was performed as a five-phase dynamic-enhanced three-dimensional (3D) fast spoiled gradient recalled acquisition in steady state (GRASS) sequence on a 1.5-T system, with double-dose bolus contrast and saline injection. The levels at which the artery of Adamkiewicz and drainage vein originated were determined. Signal intensities of the two vessels were measured with source images to assess the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and necessity of the double-subtraction technique. RESULTS: The artery of Adamkiewicz was detected in 140 patients (82.4%). Branching occurred at levels T8-T12 on the left and T8-T11 on the right. An additional anterior radiculomedullary artery was detected in 18 patients. The drainage vein was detected in 133 patients (78.2%). It merged at the T9-L2 level on both sides. In six of the 133 patients (4.5%), the drainage vein branched upwardly. Neither SNR nor CNR differed significantly between the artery of Adamkiewicz and the drainage vein in the arterial phase; but on the subtraction image, signal intensity of the artery was higher than that of the drainage vein (P < 0.05). CONCLUSION: Double-subtraction MRA is useful for detecting the artery of Adamkiewicz when it is necessary to differentiate it from the drainage vein.
Abstract: Peripheral vascular malformations are now described according to some accepted guidelines, and the principle of proper treatment (nodus ablation) is becoming clear. An appropriate classification schema for vascular anomalies and definite indications for treatment are important to successful treatment overall. Non-invasive imaging (US, CT, and MRI) in association with clinical findings is critical in establishing the diagnosis, evaluating the extent of the malformation, and planning appropriate treatment. Direct nidus phlebography is useful not only in making a correct diagnosis but also in treating the lesion by sclerotherapy. When a patient suffers clinical complications, the nidus sclerotherapy becomes mandatory. If the vascular malformation remains bloodstream to a drainage vein during nidus opacification, flow control is necessary to achieve complete nidus ablation. A multidisciplinary approach is needed in the treatment of a high-flow lesion. A dedicated team approach is necessary for appropriate management in most cases.
Abstract: The stent-graft is a device constructed from a stent and vascular graft and is inserted by means of an interventional procedure under imaging guidance. In 1986, Balko et al. reported the first stent-graft experiment, in which a Z stent covered with polyurethane was inserted into an animal aorta. In the early 1990s, Parodi et al. reported clinical introduction of the stent-graft for abdominal aortic aneurysm. In comparison to the abdominal aortic stent-graft, the thoracic stent-graft has several disadvantages, including difficulties associated with the aortic arch curvature and the relatively large caliber of the stent-graft, and the risk of central nervous system or spinal complication. However, the thoracic stent-graft is advantageous because of minimal procedural invasiveness in comparison to surgical graft replacement. In 1994, Dake et al. reported transluminal placement of an endovascular stent-graft for thoracic aortic aneurysm, and Kato et al. reported use of a stent-graft for aortic dissection and suggested that the stent-graft could be considered an alternative to surgical treatment.
Abstract: In the thoracolumbar region, it is well known that the great anterior medullary artery (the artery of Adamkiewicz: AKA) is the dominant feeder of the spinal cord. During surgery for posterior mediastinal tumor adjacent to the lower thoracic aorta, perioperative distortion of the spinal cord blood supply could lead to neurological complication. To avoid postoperative paralysis, it would be useful to know the level of the intercostal artery from which the AKA originates. Recently, we have attempted to identify the AKA preoperatively using magnetic resonance angiography (MRA).
Abstract: Peripheral vascular malformations are now described according to some accepted guidelines, and the principle of proper treatment (nidus ablation) is becoming clear. An appropriate classification scheme for vascular anomalies and definite indications for treatment are important to successful treatment overall. The findings from noninvasive imaging (ie, Doppler ultrasonography, computed tomography, or magnetic resonance imaging) in association with clinical findings are critical in establishing the diagnosis, evaluating the extent of the malformation, and planning appropriate treatment. Direct opacification of the nidus is useful, not only in making a correct diagnosis, but also in treating the lesion with sclerotherapy. In most cases, conservative treatment is recommended, but when a patient suffers clinical complications (eg, ulceration, pain, hemorrhage, cardiac failure, or unacceptable cosmetic consequences), the nidus sclerotherapy becomes mandatory. If the vascular malformation has blood outflow to a drainage vein during nidus opacification, flow control (with balloon occlusion, tourniquet, or embolization) is necessary to achieve sclerosant stasis within the nidus. Embolotherapy (with a coil, n-butyl cyanoacrylate, or small particles) should be used for subsequent multifaceted palliative therapy. A multi-disciplinary approach is needed in the treatment of a high-flow lesion, and a dedicated team approach is necessary for appropriate management in most cases.
Abstract: To plan stent-grafting for thoracic aortic aneurysm with complicated morphology, we created a virtual stent-grafting program [Semi Automatic Virtual Stent (SAVS) designer] using three-dimensional CT data. The usefulness of the SAVS designer was evaluated by measurement of transformed anatomical and straight stents. Curved model images (source, multi-planer reconstruction and volume rendering) were created, and a hollow virtual stent was produced by the SAVS designer. A straight Nitinol stent was transformed to match the curved configuration of the virtual stent. The accuracy of the anatomical stent was evaluated by experimental strain phantom studies in comparison with the straight stent. Mean separation length was 0 mm in the anatomical stent [22 mm outer diameter (OD)] and 5 mm in the straight stent (22 mm OD). The straight stent strain voltage was four times that of the anatomical stent at the stent end. The anatomical stent is useful because it fits the curved structure of the aorta and reduces the strain force compared to the straight stent. The SAVS designer can help to design and produce the anatomical stent.
Abstract: PURPOSE: To prospectively evaluate the detection of the artery of Adamkiewicz at magnetic resonance (MR) angiography and the effect such detection has on outcome after surgical graft placement in a series of patients with thoracoabdominal aortic disease. MATERIALS AND METHODS: This study had ethics committee approval, and written informed consent was obtained from all patients. Fifty patients (38 men, 12 women; age range, 47-83 years; mean age, 67.2 years) who were scheduled to undergo thoracoabdominal aortic surgery for treatment of thoracoabdominal aortic aneurysm (n = 42) or thoracoabdominal aortic dissection (n = 8) were enrolled in the study. MR angiography was performed with a 1.5-T system by using dynamic three-dimensional fast spoiled gradient-recalled acquisition in the steady state with a bolus of contrast material and saline injection (4 mL/sec). Differences in the cross-clamping time, bypass time, total surgery time, and spinal complication rate between patients in whom the artery of Adamkiewicz was identified (group A) and those in whom the artery was not identified (group B) were evaluated with chi(2) or Mann-Whitney U testing. RESULTS: In 42 of the 50 patients (84% [group A]), at least one artery of Adamkiewicz was seen to arise from an intercostal artery. Two arteries of Adamkiewicz were identified in four of the patients (8%). The artery of Adamkiewicz could not be detected with MR angiography in eight patients (group B). The ranges of cross-clamping, bypass, and total surgery times, respectively, were 30-199 minutes (mean, 78.4 minutes +/- 39.1 [standard deviation]), 30-298 minutes (mean, 96.9 minutes +/- 60.0), and 135-665 minutes (mean, 354.9 minutes +/- 133.9) in group A and 53-124 minutes (mean, 72.8 minutes +/- 29.8), 10-124 minutes (mean, 66.0 minutes +/- 41.0), and 220-405 minutes (mean, 315.6 minutes +/- 68.8) in group B. Spinal complications occurred in two patients in group B but in none of the patients in group A (P < .001). CONCLUSION: The artery of Adamkiewicz was detected in a large percentage of patients in whom there were no spinal complications, unlike the spinal complications that occurred in the patients in whom the artery was not detected.
Abstract: BACKGROUND: The purpose of this study was to determine whether the artery of Adamkiewicz (ARM) can be detected by magnetic resonance angiography and to determine the usefulness of preoperative magnetic resonance angiography evaluation of the ARM. METHODS: Between April 2000 and December 2003, 120 patients underwent magnetic resonance angiography for detection of the ARM. The morphology of the anterior spinal artery at the ARM junction, as revealed by magnetic resonance angiography, in 99 patients in whom ARM was preoperatively detected was classified into the following three types: noncontinuation of the anterior spinal artery above the ARM junction (type A), continuation of the anterior spinal artery above and below the ARM junction (type B), and noncontinuation of the anterior spinal artery below the ARM junction (type C). RESULTS: The ARMs were detected in 99 (83%) of 120 patients, and from a total of 110 ARMs 105 (95%) originated from intercostal arteries branching from the left side and 94 (86%) originated between Th9 and Th11. Two ARMs were found in 11 (11%) of 99 patients in whom ARMs were detected. In 107 patients, who underwent magnetic resonance angiography to reveal the morphology of the anterior spinal artery at the ARM junction, the patterns of the anterior spinal artery were type A in 59 patients (55%), type B in 21 patients (20%), type C in 3 patients (3%) and not classified in 24 patients (22%). No spinal cord injury occurred in patients in whom the ARM had been preoperatively detected. CONCLUSIONS: Preoperative detection of the ARM is possible by magnetic resonance angiography and is very useful for reducing the incidence of ischemic injury of the spinal cord.
Abstract: OBJECTIVE: The outcome of thoracoabdominal or descending aortic aneurysm repair after preoperative demonstration of the artery of Adamkiewicz (ARM) by magnetic resonance angiography (MRA) was investigated. METHODS: Between January 2000 and December 2001, 40 consecutive patients who had aneurysms of the thoracoabdominal or descending aorta underwent preoperative MRA to visualize the ARM. Thirty-two patients underwent replacement of the aneurysms, and 25 patients (TAAA, 11; TAA, 14) underwent replacement of the aneurysms with preoperative detection of the ARM. Only intercostal or lumbar arteries in aneurysms, which were detected as the origin of the ARM, were reattached to the graft. The results of thoracoabdominal aortic aneurysm operations in 11 patients in whom the ARM was preoperatively detected (group I) were compared with the results of TAAA operations in 26 patients in whom the ARM was not preoperatively detected (group II). RESULTS: MRA demonstrated the ARM in 29 (73%) of the 40 patients. The laterality of the arteries originated from the left side in 29 (100%) and between Th9 and Th12 in 25 (86%), between Th9 and L1 in 28 (97%) of the 29 patients. No spinal cord injury occurred in patients (TAAA and TAA) in whom the ARM had been preoperatively detected. Major complications following TAAA operations included paraplegia (0% in group I and 8% in group II), respiratory failure (9% in group I and 23% in group II), and renal failure requiring hemodialysis (18% in group I and 22% in group II). Operation times were 439+/-99 min in group I and 620+/-200 min in group II (P=0.008). CONCLUSIONS: Preoperative detection of the ARM is possible by MRA and is very useful for reducing the incidence of ischemic injury of the spinal cord and for reducing the time of an operation for repair of an aneurysm of the thoracoabdominal or descending aorta.
Abstract: Two high-risk patients underwent a graft replacement for descending thoracic or thoracoabdominal aortic aneurysms without the reconstruction of any intercostal and lumbar arteries. The first patient was an 81-year-old woman with asthma and renal dysfunction who was diagnosed to have a descending thoracic aortic aneurysm extending from the Th8 to Th12 level. Contrast magnetic resonance angiography (MRA) demonstrated the Adamkiewicz artery to originate from the left second lumbar artery. The second patient was a 59-year-old man with left ventricular dysfunction due to aortic and mitral stenoses who was diagnosed to have a Crawford type IV thoracoabdominal aortic aneurysm. Contrast MRA showed the Adamkiewicz artery to originate from the left ninth intercostal artery. In general, the reestablishment of the spinal cord's blood supply, whenever possible, is generally considered to be necessary in such patients to prevent spinal cord injury. However, the reimplantation of intercostal vessels is the most complex aspect of this surgical modality, and therefore, it may cause a substantial increase in the cardiopulmonary bypass time. However, at least in some cases, such as the two cases presented herein, the use of contrast MRA was found to reduce the risk in surgery for descending thoracic or thoracoabdominal aortic aneurysms by eliminating the need for any intraoperative management of the intercostal and lumbar arteries.
Abstract: It is recently controversial whether distal fenestration is necessary in graft replacement for chronic aortic dissection. Several groups started to try the exclusion of intimal entry by the insertion of a stent-graft as a treatment for chronic aortic dissection, while conventional surgical techniques consisted of graft replacement with distal anastomosis to both the true and false channels. It should be kept in mind that the resultant occlusion of the false lumen after obliteration of the false channel could promote spinal cord ischemia. We report a patient with delayed paraplegia after graft replacement without distal fenestration for chronic type B aortic dissection. It is possible that not all cases of chronic aortic dissection are good for stent-grafting.
Abstract: We report a case of extravasation of an antitumor agent by preoperative magnetic resonance (MR) imaging. MR studies demonstrated a decreased signal intensity on T1- and T2-weighted images and a strong enhancement of contrast media in injured tissue, including subcutaneous adipose tissue and deep fascia, which was cicatrical macroscopically. The MR findings were in good agreement with the macroscopic findings. We believe that MR imaging is useful for estimating deep tissue damage due to extravasation of an antitumor agent.
Abstract: We report the case of a young man presenting with high-flow arteriovenous malformation (AVM), in whom percutaneous direct nidus puncture ethanolamine oleate (EO) sclerotherapy was useful in the management of the AVM. To our knowledge, this is the first report of percutaneous trans-nidus EO sclerotherapy for AVM in the extremities. Percutaneous trans-nidus sclerotherapy should be considered as an alternative choice for the management of symptomatic AVM.
Abstract: Post-traumatic high flow priapism is a rare disease. A review of English published reports revealed 63 cases. Enhanced computed tomography (CT) of the penis has not previously been used as a diagnostic method for post-traumatic high flow priapism. We present a case of post-traumatic high flow priapism diagnosed with enhanced CT of the penis. Additionally, diagnostic modalities for post-traumatic high flow priapism are discussed with review of published work.
Abstract: Pheochromocytoma is a chromaffin tumor in which 10% are extra-adrenal and 10% are malignant. I-131 metaiodobenzylguanidine (MIBG) scintigraphy has an important role in the identification of these tumors and investigation of metastatic lesions. The authors describe a 36-year-old woman who underwent resection of a malignant left adrenal pheochromocytoma who was thought to have metastases in the liver and para-aortic lymph nodes. Fusion images of I-131 MIBG SPECT and magnetic resonance studies were obtained to properly identify the metastatic lesions. These fusion images helped greatly in subsequent surgery.
Abstract: We compared the findings of magnetic resonance (MR) images and pathological examination to determine whether or not MR images reflect pathological changes following microwave coagulation therapy (MCT) on liver tissue. We used microwave (generating frequency 2450 Mhz, wave length 12 cm, output 50 W, 60 second duration) to irradiate six canine livers under general anesthesia. After the animals were sacrificed, the livers were resected. The irradiated regions were cut with margins and divided into two pieces, one for MR study, and the other for pathological examination. The findings were compared. From the center to the marginal layer, the irradiated region presented 4/3 laminal patterns on T1/T2-weighted images: low/high, high/low, very high/high, and iso-low/high intensity. On gradient-echo imaging, the irradiated regions presented no decreasing signals using several echo time lengths. With hematoxylin and eosin stain, MR laminar patterns reflected the histopathological changes, as follows: a tissue loss area surrounding the inserted needle, low/high; decreased sinusoidal width with/without necrotic tissue, high/low; sinusoidal width dilation at the periphery, very high/high; and fatty degenerated tissue surrounding the irradiated area at the boundary of the normal hepatocytes, iso-low/high. The MR signal intensity, which reflected the histopathological changes, presented tissue characterization after MCT, and the macromolecular hydration effect influenced the high intensity on T1-weighted images.
Abstract: We report a fetus with a giant neck hemangioma which was examined by MRI in utero. The initial diagnosis was made by ultrasonography. The sonolucent aspect of the mass, together with the presence of pulsating Doppler flow signals, was highly suggestive of a fetal hemangioma. In late pregnancy, fetal MRI revealed the location, size and characteristics of the neck tumor. Following prenatal corticosteroid treatment and premature delivery of the pregnancy due to fetal cardiac failure, the newborn received angiography and coil embolization of the tumor vessels. Despite vigorous treatments, the newborn died 12 h after birth. Evaluation of a fetal neck hemangioma by MRI is recommended late in pregnancy for precise information on the tumor and adjacent organs since the image is valuable for planning optimal perinatal treatment.
Abstract: PURPOSE: To evaluate the indication and advantages of venous sac embolization of pulmonary arteriovenous malformations (PAVMs) using interlocking detachable coils (IDCs). METHODS: We performed percutaneous embolization in 12 PAVMs in four patients using IDCs, initially placed in the venous sac or at the feeding artery to prevent systemic migration of additional coils. We placed the IDCs in the venous sac in PAVMs with the following vascular architecture: the draining vein was larger than the feeding arteries and both vessels were interposed with the venous sac or there were short feeding arteries. RESULTS: Complete occlusion was achieved in all 12 PAVMs without significant complications. We deployed IDCs in the venous sac in eight PAVMs and in the feeding artery in four. CONCLUSION: Venous sac embolization may be beneficial in PAVMs with large out-flow vessels or short feeding arteries. IDCs are suitable for this procedure.
Abstract: Laparoscopic microwave coagulation (LMC) for hepatocellular carcinomas (HCCs) was performed on 26 HCCs in 17 patients. Contrast-enhanced CT (CECT) and MR images (T1-weighted imaging [T1WI], T2WI, gadolinium-diethylenetriamine pentaacetic acid [Gd-DTPA] T1WI) were obtained to determine changes over time. The irradiated center exhibited low to moderate intensity with surrounded high intensity (HI) on T2WI and Gd-DTPA T1WI. On T1WI, lesions showed four patterns of intensity: uniform HI (30.8%), arcuate HI (26.9%), mainly low with spot HI (30.8%), and isointensity to hypointensity (11.5%). Follow-up imaging at more than 170 days revealed isointensity to hypointensity on T1WI (96.2%) and reduced HI on T2-weighted imaging (T2WI) and Gd-DTPA T1WI. All lesions became less conspicuous and were reduced in volume. HCC shows time-related changes in signals and size after LMC. Identifying the irradiated lesion is necessary to estimate the adequacy of treatment by comparison with the pretherapeutic image.
Abstract: OBJECTIVE: The esophagus occasionally crosses the descending aorta at an unusually high level (3-5 cm inferior to the carina) in right-sided scoliosis. The purpose of this study was to analyze the mechanism of this finding. MATERIALS AND METHODS: We prospectively evaluated thoracic CT scans in 30 patients with right-sided scoliosis. We assessed the alterations in the positions of the esophagus and the descending aorta by the thoracic deformity. RESULTS: The descending aorta followed the scoliotic curve of the spine in 26 (87%) patients. The esophagus followed the scoliotic curve of the spine in 14 (47%) patients and did not in 16 (53%). The anteroposterior diameter of the thorax in the former group was significantly smaller than that in the latter (p < 0.01). High level cross of both structures was identified in 14 (47%) patients, and all of them belonged to the group in which the esophagus did not follow the scoliotic curve of the spine. CONCLUSION: The unusual high level cross of the esophagus with the descending aorta occasionally seen in scoliosis is due to a difference in the positional alterations of the two structures resulting from the scoliosis.
Abstract: A case of an isolated dissecting aneurysm of the superior mesenteric artery is presented with findings of three-dimensional CT imaging. False lumen, intimal flap, entry, and re-entry are clearly identified on three-dimensional CT imaging.
Abstract: A retrospective evaluation was performed to determine whether accelerated hyperfractionation (AHF) improves the survival rate of patients with malignant gliomas. One hundred and seven patients with malignant gliomas, including glioblastoma multiforme, who had received radical radiotherapy were evaluated. Of the patients, 36 were treated by conventional fractionation (CF), and 71 by AHF. The treatment results of the two regimens were compared with regard to survival rate after therapy. Treatment by AHF was conducted at 10-15 F/W (1.5 Gy/F); the mean total dose was 61 Gy over an average of 27 days. Treatment by CF was conducted at 5 F/week (1.8-2 Gy/F); the mean total dose was 59 Gy over 51 days. Multivariate analysis using Cox's proportional hazard model revealed that AHF significantly increased survival rate. Besides pointing to the selection of the AHF method as a treatment regimen, multivariate analysis showed the following factors to be indicators of favorable prognosis: a histopathological diagnosis other than glioblastoma multiforme, age below 40 years, and supratentorial location of the tumor.
Abstract: PURPOSE: To assess the frequency, location, correlation with age, and cause of partial obliteration of the descending aortic interface on normal frontal chest radiographs. MATERIALS AND METHODS: Concurrent chest radiographs and computed tomographic (CT) scans of 1,500 patients in whom CT findings excluded a diagnosis of paraaortic pathologic processes were reviewed retrospectively. RESULTS: Aortic interface obliteration was identified on 134 images (8.9%), which included 43 (2.9%) in the suprahilar and upper hilar portion, 56 (3.7%) in the lower hilar portion, and 46 (3.1%) in the cardiac portion of the interface. The causes were direct contact with or proximity to the aortic margin by pulmonary arteries at the suprahilar and upper hilar portion, superior segment vessels at the lower hilar portion, and various structures, including left inferior pulmonary vein, mediastinal fat, and left ventricle at the cardiac portion. CONCLUSION: Partial aortic interface obliteration can be seen on normal frontal chest radiographs because of obstruction by small adjacent structures.
Abstract: In six small renal angiomyolipomas (7-17 mm) the superiority of displaying the CT numbers of pixels within a lesion (pixel mapping) over the usual region of interest (ROI) measurement is described in the detection of small amounts of fat tissue. On precontrast 5 mm CT the ROI measurements were > 0 in four cases whereas pixel maps revealed pixels with values < 0 in six cases.
