Hyperplastic anterior choroidal artery identified using magnetic resonance angiography: a report of two cases.
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Adult↗
Biomedical subjects
Max Wintermark
Publications and source records attributed to Max Wintermark.
Cerebral blood flow thresholds in acute stroke triage.
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Cerebrovascular Circulation↗
Perfusion-CT assessment of infarct core and penumbra: receiver operating characteristic curve analysis in 130 patients suspected of acute hemispheric stroke.
BACKGROUND AND PURPOSE: Different definitions have been proposed to define the ischemic penumbra from perfusion-CT (PCT) data, based on parameters and thresholds tested only in small pilot studies. The purpose of this study was to perform a systematic evaluation of all PCT parameters (cerebral blood flow, volume [CBV], mean transit time [MTT], time-to-peak) in a large series of acute stroke patients, to determine which (combination of) parameters most accurately predicts infarct and penumbra. METHODS: One hundred and thirty patients with symptoms suggesting hemispheric stroke < or =12 hours from onset were enrolled in a prospective multicenter trial. They all underwent admission PCT and follow-up diffusion-weighted imaging/fluid-attenuated inversion recovery (DWI/FLAIR); 25 patients also underwent admission DWI/FLAIR. PCT maps were assessed for absolute and relative reduced CBV, reduced cerebral blood flow, increased MTT, and increased time-to-peak. Receiver-operating characteristic curve analysis was performed to determine the most accurate PCT parameter, and the optimal threshold for each parameter, using DWI/FLAIR as the gold standard. RESULTS: The PCT parameter that most accurately describes the tissue at risk of infarction in case of persistent arterial occlusion is the relative MTT (area under the curve=0.962), with an optimal threshold of 145%. The PCT parameter that most accurately describes the infarct core on admission is the absolute CBV (area under the curve=0.927), with an optimal threshold at 2.0 ml x 100 g(-1). CONCLUSIONS: In a large series of 130 patients, the optimal approach to define the infarct and the penumbra is a combined approach using 2 PCT parameters: relative MTT and absolute CBV, with dedicated thresholds.
Adult↗
Association between extrinsic and intrinsic carpal ligament injuries at MR arthrography and carpal instability at radiography: initial observations.
PURPOSE: To retrospectively compare the presence or absence of carpal instability on radiographs with the findings of magnetic resonance (MR) arthrographic evaluation of intrinsic and extrinsic ligament tears in patients with chronic wrist pain. MATERIALS AND METHODS: The institutional review board approved this study and did not require informed consent. Signs of carpal instability were assessed on static and dynamic radiographs of the wrist obtained in 72 patients (24 female, 48 male; mean age, 36 years; age range, 14-59 years) with posttraumatic wrist pain. MR arthrography was subsequently performed. Two musculoskeletal radiologists independently analyzed the radiographs and MR images. Each intrinsic and extrinsic ligament was individually evaluated for the presence of a ligament tear. The extent of the tear also was recorded. Interobserver agreement regarding MR arthrographic findings was tested by calculating kappa statistics. Statistical comparison between radiography and MR arthrography was performed by using the Fisher exact test. RESULTS: Twenty-five triangular fibrocartilage complex, 18 (five partial, 13 complete) scapholunate ligament, and 25 (10 partial, 15 complete) lunotriquetral ligament tears were visualized. Twenty-two (all complete) extrinsic ligament tears were detected: two radial collateral ligament, 10 radioscaphocapitate ligament, and 10 radiolunotriquetral ligament tears. Interobserver agreement regarding intrinsic and extrinsic ligament tear detection at MR arthrography was excellent (kappa = 0.80). Nineteen patients had evidence of carpal instability on radiographs. Fourteen (52%) of 27 patients with at least one complete intrinsic lesion had no sign of carpal instability. On the other hand, the association of scapholunate ligament and/or lunotriquetral ligament and extrinsic ligament tears was significantly correlated (P < .001) with carpal instability at radiography. CONCLUSION: The presence or absence of carpal instability on radiographs depends on the association between intrinsic and extrinsic ligament tears-even partial ones-rather than on the presence of intrinsic ligament tears alone, even when the tears are complete.
Adolescent↗
Unmasking complicated atherosclerotic plaques on carotid magnetic resonance angiography: a report of three cases.
In stenotic lesions of the extracranial carotid arteries, the presence of intraplaque hemorrhage or thrombosed ulceration is considered to pose an additional risk. Although contrast-enhanced magnetic resonance angiography (MRA) is a powerful means for looking at the vascular lumen, it provides little information on the vessel wall, particularly when mask subtraction methods are used. We report three cases in which the maximal intensity projections obtained from gadolinium-enhanced MRA source images showed only internal carotid artery stenoses, whereas source images revealed a focal increased T1 signal in the wall of the internal carotid artery, representing either intraplaque hemorrhage or thrombosed ulceration. Hence, the physicians interpreting an MRA in an acute stroke patient should not limit themselves to the synthetic maximal intensity projections but should also always review the source partitions, which can contain information related to an acute intraplaque accident.
Aged↗
Iodinated and gadolinium contrast media in computed tomography (CT) and magnetic resonance (MR) stroke imaging.
Thrombolysis has become an approved therapy for acute stroke. However, many stroke patients do not benefit from such treatment, since the presently used criteria are very restrictive, notably with respect to the accepted time window. Even so, a significant rate of intracranial hemorrhage still occurs. Conventional cerebral computed tomography (CT) without contrast has been proposed as a selection tool for acute stroke patients. Recently, more modern magnetic resonance imaging (MRI) and CT techniques, referred to as diffusion- and perfusion-weighted imaging, and perfusion-CT, have been introduced. They afford a comprehensive noninvasive survey of acute stroke patients as soon as their emergency admission, with accurate demonstration of the site of arterial occlusion and its hemodynamic and pathophysiological repercussions of the brain parenchyma. The objective of this review article is to present the advantages and drawbacks of CT, using iodinated contrast, and MRI, using gadolinium, in the evaluation of acute stroke patients.
Gadolinium↗
Comparative overview of brain perfusion imaging techniques.
BACKGROUND AND PURPOSE: Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks. SUMMARY OF REVIEW: This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview established by consensus among specialists of the various techniques. CONCLUSIONS: For clinicians, this article should offer a clearer picture of the pros and cons of currently available brain perfusion imaging techniques and assist them in choosing the proper method for every specific clinical setting.
Aged↗
Brain perfusion-CT in acute stroke patients.
The role of neuro-imaging in the evaluation of acute stroke has changed dramatically in the past decade. Previously, neuro-imaging was used in this setting to provide anatomic imaging that indicated the presence or absence of acute cerebral ischemia and excluded lesions that produce symptoms or signs mimicking those of stroke, such as hemorrhage and neoplasms. More recently, the introduction of thrombolysis has changed the goals of neuro-imaging from providing solely anatomic information to providing physiologic information that could help to determine which patients might benefit from therapy. In particular, significant emphasis has been placed on the delineation of the ischemic penumbra, also called tissue at risk. Modern CT survey, consisting of three indissociable elements: noncontrast CT (NCT) of course, perfusion-CT (PCT) and CT-angiography (CTA), fulfill all the requirements for hyperacute stroke imaging. CTA can define the occlusion site, depict arterial dissection, grade collateral blood flow, and characterize atherosclerotic disease, whereas PCT accurately delineates the infarct core and the ischemic penumbra. CT offers a number of practical advantages over other cerebral perfusion imaging methods, including its wide availability. Using PCT and CTA to define new individualized strategies for acute reperfusion will allow more acute stroke patients to benefit from thrombolytic therapy.
Acute Disease↗
Accuracy of dynamic perfusion CT with deconvolution in detecting acute hemispheric stroke.
BACKGROUND AND PURPOSE: Dynamic perfusion CT (PCT) with deconvolution produces maps of time-to-peak (TTP), mean transit time (MTT), regional cerebral blood flow (rCBF), and regional cerebral blood volume (rCBV), with a computerized automated map of the infarct and penumbra. We determined the accuracy of these maps in patients with suspected acute hemispheric stroke. METHODS: Forty-six patients underwent nonenhanced CT and dynamic PCT, with follow-up CT or MR imaging. Two observers reviewed the nonenhanced studies for signs of stroke and read the PCT maps for TTP, MTT, rCBF, and rCBV abnormalities. Sensitivity, specificity, accuracy, and interobserver agreement were compared (Wilcoxon tests). Nonenhanced CT and PCT data were reviewed for stroke extent according to previously reported methods. Sensitivity, specificity, and accuracy of the computerized maps in detecting ischemia and its extent were determined. RESULTS: Compared with nonenhanced CT, PCT maps were significantly more accurate in detecting stroke (75.7-86.0% vs. 66.2%; P <.01), MTT maps were significantly more sensitive (77.6% vs. 69.2%; P <.01), and rCBF and rCBV maps were significantly more specific (90.9% and 92.7%, respectively, vs. 65.0%; P <.01). Regarding stroke extent, PCT maps were significantly more sensitive than nonenhanced CT (up to 94.4% vs. 42.9%; P <.01) and had higher interobserver agreement (up to 0.763). For the computerized map, sensitivity, specificity, and accuracy, respectively, were 68.2%, 92.3%, and 88.1% in detecting ischemia and 72.2%, 91.8%, and 87.9% in showing the extent. CONCLUSION: Dynamic PCT maps are more accurate than nonenhanced CT in detecting hemispheric strokes. Despite limited spatial coverage, PCT is highly reliable to assess the stroke extent.
Adult↗
Acute brain perfusion disorders in children assessed by quantitative perfusion computed tomography in the emergency setting.
OBJECTIVE: Perfusion computed tomography (CT) is a simple imaging technique that allows accurate quantitative assessment of brain perfusion. Perfusion CT is an ideal imaging technique to be used in the emergency setting and has thus gained recognition in the early management of adult acute stroke patients. Perfusion CT can be applied to children successfully by using adequate imaging protocols. The goal of this article is to provide a pictorial essay of the perfusion CT features of diseases that affect brain perfusion as depicted in a population of children who were evaluated in the emergency CT unit of our institution. METHODS: During the period of September 2001 to October 2002, all the children, who were evaluated in the emergency CT unit of our institution and who were prescribed with a cerebral CT and an intravenous administration of iodinated contrast material, underwent a perfusion-CT examination. Perfusion-CT maps were reviewed in the patients diagnosed as abnormal on the basis of follow-up clinical/radiological examinations and correlated with the results of these tests. RESULTS: Brain perfusion-CT examinations have been performed in 77 children. Fifty-three patients were considered as normal, based on normal conventional cerebral CT and normal clinical/radiological follow-up. Perfusion-CT results showed major abnormalities in 14 cases among the 24 remaining patients, related to brain ischemia in 2, head trauma in 9, brain infection in 2, and sickle cell disease in 1. These abnormalities consisted in low regional cerebral blood flow and volume values, and in high mean transit time values. They demonstrated typical anatomical distribution, depending on the considered pathological condition. CONCLUSIONS: Perfusion CT provides quantitative assessment of child brain perfusion disorders. Its ability to be easily performed upon admission makes it an ideal emergency tool that advantageously competes with other imaging techniques such as perfusion-weighted magnetic resonance imaging, despite its limited spatial coverage. Its usefulness with respect to the impact on treatment and outcome, however, remains to be established in further studies.
Adolescent↗
Relationship between brain perfusion computed tomography variables and cerebral perfusion pressure in severe head trauma patients.
OBJECTIVE: To compare brain perfusion-computed tomography (CT) results with invasive cerebral perfusion pressure (CPP) monitoring in severe head trauma patients. DESIGN: Prospective cohort study. SETTING: Emergency room and surgical intensive care unit of our hospital. PATIENTS: Sixty-one severe head trauma patients. INTERVENTIONS: We prospectively collected 103 perfusion-CT examinations with simultaneous measurement of mean arterial pressure and intracranial pressure, affording calculation of CPP. The statistical relationship between perfusion-CT results and the corresponding CPP values was evaluated using Wilcoxon (Mann-Whitney) and generalized F-tests. The functional outcome of the 61 patients was evaluated 3 months after trauma on the basis of the Glasgow Outcome Scale score and compared between groups using Fisher's exact tests. MEASUREMENTS AND MAIN RESULTS: Perfusion-CT enabled us to distinguish between two groups of patients. Within each group, a significant correlation (p <.001) between the CPP values and the corresponding perfusion-CT results was demonstrated. There was also a significant correlation (p <.001) between the CPP values and the extent of the abnormal perfusion-CT areas (R up to.817). The first group was characterized by a weak dependence of perfusion-CT results on the corresponding CPP values (low slope) and the second group by a strong dependence (steep slope). These groups were interpreted as having preserved (or pseudo) and impaired cerebral vascular autoregulation, respectively. The functional outcome was better in the second group of patients. CONCLUSIONS: Intermittent perfusion-CT measurements plus continuous CPP measurement provide more information than continuous CPP alone. Perfusion-CT gives unique information regarding regional heterogeneity of brain perfusion. It might allow clinicians to distinguish between patients with preserved auto-regulation (or pseudoautoregulation) and those with impaired autoregulation and could therefore guide interpretation of CPP measurements and therapy.
Adult↗
Admission perfusion CT: prognostic value in patients with severe head trauma.
PURPOSE: To assess the prognostic value of admission perfusion computed tomography (CT) in patients with severe head trauma. MATERIALS AND METHODS: This prospective study included 130 patients with severe trauma, aged 19-86 years, admitted with a Glasgow Coma Scale score of 8 or less. They underwent perfusion CT as part of their admission CT survey. Clinical data, unenhanced cerebral CT findings, and perfusion CT scans were evaluated with respect to the Glasgow Outcome Scale (GOS) score at 3 months. Perfusion CT features were evaluated in patients with intracranial hypertension, cerebral contusions, and juxtadural hematomas. Ordered logistic regression was used to determine risk factors for an unfavorable GOS score at 3 months. RESULTS: Perfusion CT was more sensitive than conventional unenhanced CT in the detection of cerebral contusions. Perfusion CT featured specific patterns with respect to patient outcome, with normal brain perfusion or hyperemia in patients with favorable outcome, and oligemia in patients with unfavorable outcome. The number of arterial territories with low regional cerebral blood volume at perfusion CT was an independent prognostic factor (P =.008), as were mean arterial pressure at the scene of accident (P =.083), base excess at admission (P =.002), presence of skull fractures (P =.041), and signs of herniation (P =.013) at admission unenhanced cerebral CT. Perfusion CT also showed a range of brain perfusion alterations in patients with juxtadural collections, cerebral edema, or intracranial hypertension. CONCLUSION: Perfusion CT in patients with severe head trauma provides independent prognostic information regarding functional outcome.
Adult↗
Brain perfusion in children: evolution with age assessed by quantitative perfusion computed tomography.
OBJECTIVE: The objective of this study was to assess the age-related variations of brain perfusion through quantitative cerebral perfusion computed tomography (CT) results in children without brain abnormality. METHODS: Brain perfusion CT examinations were performed in 77 children, aged 7 days to 18 years. These patients were admitted at our institution for both noncontrast and contrast-enhanced cerebral CT. Only children whose conventional cerebral CT and clinical/radiologic follow-up, including additional investigations, were normal were taken into account for this study (53 of 77). RESULTS: The average regional rCBF amounts to 40 (mL/100 g per minute) for the first 6 months of life, peaks at approximately 130 (mL/100 g per minute) at approximately 2 to 4 years of age, and finally stabilizes at approximately 50 (mL/100 g per minute) at approximately 7 to 8 years of age, with a small increase of rCBF values at approximately 12 years of age. The rCBF in the gray matter averages 3 times that in the white matter, except for the first 6 months of life. The global CBF represents 10% to 20% of the global cardiac output for the first 6 months of life, peaks at approximately 55% by 2 to 4 years of age, and finally stabilizes at approximately 15% by 7 to 8 years of age. Specific age-related evolution patterns were identified in the different anatomic areas of the cerebral parenchyma, which could be related to the development of neuroanatomic structures and to the emergence of corresponding cognitive functions. CONCLUSIONS: Quantitative perfusion CT characterization of brain perfusion shows specific age variations. Brain perfusion of each cortical area evolves according to a specific time course, in close correlation with the psychomotor development.
Adolescent↗
Dynamic perfusion CT: optimizing the temporal resolution and contrast volume for calculation of perfusion CT parameters in stroke patients.
BACKGROUND AND PURPOSE: Numerous parameters are involved in dynamic perfusion CT (PCT). We assessed the influence of the temporal sampling rate and the volume of contrast material. METHODS: Sixty patients with ischemic hemispheric stroke lasting > or = 12 hours underwent PCT. Groups of 15 patients each received 30, 40, 50, or 60 mL of contrast agent. Regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), mean transit time (MTT), and time-to-peak (TTP) maps were calculated for temporal sampling intervals of 0.5, 1, 2, 3, 4, 5, and 6 seconds. Results were statistically compared. Signal-to-noise ratios (SNRs), duration of arterial entrance to venous exit, and radiation dose were also assessed. RESULTS: Increasing temporal sampling intervals lead to significant overestimation of rCBV, rCBF, and TTP and significant underestimation of MTT compared with values for an interval of 1 second. Maximal allowable intervals to avoid these effects were 2, 3, 3, and 4 seconds for 30, 40, 50, and 60-mL boluses, respectively. Venous exit of contrast material occurred in 97.5% of patients after 36, 42, 42, and 48 seconds, respectively, for the four volumes. SNRs did not differ with volume. The effective radiation dose varied between 0.852 and 1.867 mSv, depending on the protocol. The cine mode with two 40-mL boluses and the toggling-table technique with one 60-mL bolus had the lowest doses. CONCLUSION: Temporal sampling intervals greater than 1 second can be used without altering the quantitative accuracy of PCT. Increased sampling intervals reduce the radiation dose and may allow for increased spatial coverage.
Aged↗
Thoracolumbar spine fractures in patients who have sustained severe trauma: depiction with multi-detector row CT.
PURPOSE: To determine if multi-detector row computed tomography (CT) can replace conventional radiography and be performed alone in severe trauma patients for the depiction of thoracolumbar spine fractures. MATERIALS AND METHODS: One hundred consecutive severe trauma patients who underwent conventional radiography of the thoracolumbar spine as well as thoracoabdominal multi-detector row CT were prospectively identified. Conventional radiographs were reviewed independently by three radiologists and two orthopedic surgeons; CT images were reviewed by three radiologists. Reviewers were blinded both to one another's reviews and to the results of initial evaluation. Presence, location, and stability of fractures, as well as quality of reviewed images, were assessed. Statistical analysis was performed to determine sensitivity and interobserver agreement for each procedure, with results of clinical and radiologic follow-up as the standard of reference. The time to perform each examination and the radiation dose involved were evaluated. A resource cost analysis was performed. RESULTS: Sixty-seven fractured vertebrae were diagnosed in 26 patients. Twelve patients had unstable spine fractures. Mean sensitivity and interobserver agreement, respectively, for detection of unstable fractures were 97.2% and 0.951 for multi-detector row CT and 33.3% and 0.368 for conventional radiography. The median times to perform a conventional radiographic and a multi-detector row CT examination, respectively, were 33 and 40 minutes. Effective radiation doses at conventional radiography of the spine and thoracoabdominal multi-detector row CT, respectively, were 6.36 mSv and 19.42 mSv. Multi-detector row CT enabled identification of 146 associated traumatic lesions. The costs of conventional radiography and multi-detector row CT, respectively, were 145 and 880 US dollars per patient. CONCLUSION: Multi-detector row CT is a better examination for depicting spine fractures than conventional radiography. It can replace conventional radiography and be performed alone in patients who have sustained severe trauma.
Adult↗
Aphasia in hyperacute stroke: language follows brain penumbra dynamics.
During the first few hours after onset, stroke symptoms may evolve rapidly. We studied the correlation between brain perfusion and aphasia changes during the hyperacute phase of stroke using a new technique of perfusion computed tomography (P-CT). Using an aphasia score developed for each language modality, language was evaluated within 6 hours after onset, then sequentially during the first week. Maps of the penumbra and infarct obtained from P-CT images and definite infarct size evaluated using T2 and diffusion-weighted MRI (DWI) on day 3 were rated by a neuroradiologist, blinded to the clinical deficit. Within 6 hours, deficits in all language modalities were present in 13 out of 24 consecutive patients, corresponding to large anterior-posterior perfusion deficits of the left middle cerebral artery (MCA) territory. The aphasia score correlated with a corresponding perfusion deficit in specific areas of the MCA territory, and showed significantly less improvement when the penumbra evolved toward infarction than when at least part of the penumbra was rescued. Our findings suggest a particularly good correlation between the evolution of aphasic symptoms and penumbra dynamics. Further studies on the relevance of penumbra dynamics in function-specific brain areas to decision taking in hyperacute stroke management are required.
Adult↗
Imaging of acute ischemic brain injury: the return of computed tomography.
PURPOSE OF REVIEW: Classical and modern computed tomography imaging techniques, including conventional computed tomography, perfusion-computed tomography and computed tomography-angiography for acute stroke are reviewed. RECENT FINDINGS: Thrombolysis has become an approved therapy for acute stroke. However, many stroke patients do not benefit from such treatment, since the presently used criteria are very restrictive, notably with respect to the accepted time-window. Even so, a significant rate of intracranial hemorrhage still occurs. Conventional cerebral computed tomography has been proposed as a selection tool for acute stroke patients. Recently, more modern computed tomography techniques, referred to as functional computed tomography or perfusion-computed tomography, have been introduced. Such perfusion-computed tomography techniques are competing favorably with diffusion-weighted/perfusion-weighted magnetic resonance imaging in the delineation of the penumbra. They are more easy to perform, because they are readily available and accessible in emergency settings, and less time-consuming. Furthermore, perfusion-computed tomography combined with computed tomography-angiography affords a comprehensive non-invasive survey of acute stroke patients as early as at the time of their emergency admission, with accurate demonstration of the site of arterial occlusion and its hemodynamic and pathophysiological repercussions for the brain parenchyma. SUMMARY: A renewal of computed tomography in the field of stroke has been afforded by the introduction of functional techniques such as perfusion-computed tomography, which provides promising insights into cerebral tissue viability and can be used as a guidance tool for therapy when combined with computed tomography-angiography.
Acute Disease↗
Multislice computerized tomography angiography in the evaluation of intracranial aneurysms: a comparison with intraarterial digital subtraction angiography.
OBJECT: The goal of this study was to assess the diagnostic accuracy of computerized tomography (CT) angiography performed with the aid of multislice technology (MSCT angiography) in the investigation of intracranial aneurysms, by comparing this method with intraarterial digital subtraction (IADS) angiography. METHODS: Fifty consecutive adult patients, who successively underwent MSCT angiography (four rows) and IADS angiography of intracranial vessels, were prospectively identified. The MSCT angiography studies consisted of 1.25-mm slices, with 0.8-mm reconstruction intervals, a pitch of 0.75, and timing determined by a test bolus. Two neuroradiologists, who were blinded to the initial interpretation of the MSCT angiograms as well as to those of the IADS angiograms, independently reviewed the MSCT angiograms for the detection and characterization of intracranial aneurysms. Forty-nine intracranial aneurysms were identified in 40 patients; 33 of these lesions were responsible for subarachnoid hemorrhage. The sensitivity, specificity, and accuracy of MSCT angiography in the detection of intracranial aneurysms were 94.8, 95.2, and 94.9%, respectively, on a per-aneurysm basis and 99, 95.2, and 98.3%, respectively, on a per-patient basis. Interobserver agreement was 98%. There was an excellent correlation between aneurysm size assessed using MSCT angiography and that determined by IADS angiography (slope = 0.916, r = 0.877, p < 0.001); however, 2 mm stood as the cutoff size below which the sensitivity of MSCT angiography was statistically lower. That method displayed great accuracy in characterizing the morphological characteristics of the aneurysm. CONCLUSIONS: Multislice CT angiography is an accurate and robust noninvasive screening test for intracranial aneurysms. It performs better than that reported for single-slice CT angiography. Introduction of eight- and especially 16-row MSCT angiography will provide further progression through thinner slices, a lower pitch, and a purely arterial phase.
Angiography, Digital Subtraction↗