Follow-up Computed Tomography Findings Research Articles

Post-COVID-19 pulmonary fibrosis with prognostic risk factors: A study in the hilly state of North India

Context: Coronavirus disease 19 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS CoV-2). As it is a novel coronavirus infection, its acute as well as long-term pulmonary alterations in terms of radiological imaging and pathology need to be explored. Aim: To analyze the risk factors associated with the development of pulmonary fibrosis in post-COVID-19 patients. Settings and Design: A retrospective study in a tertiary center in a hilly state of North India. Methods and Material: A retrospective study was carried out in a hilly state of North India during the second wave of the COVID-19 pandemic. A baseline computed tomography (CT) within 1 month and a follow-up CT within 3–6 months of the onset of patients’ symptoms was done. The patients were assigned two groups based on the presence of fibrosis [reticular pattern (inter/intralobular septal thickening), parenchymal bands, bronchiectasis, and/ or honeycombing] on follow-up CT. The patients’ demographic profiles, clinical records, blood laboratory findings, treatment given, baseline CT, and follow-up CT findings were compared between the fibrosis and non-fibrosis groups. Statistical analysis used: The data entry was done in the Microsoft EXCEL spreadsheet, and the final analysis was done with the use of Statistical Package for Social Sciences (SPSS) software, IBM manufacturer, Chicago, USA, ver 25.0. Results: Of the total 72 patients, two had no abnormality on baseline CT. Forty (57.14%) out of 70 patients already had fibrosis on baseline CT, which increased to involve 47 (67.14%) patients on follow-up CT. It was analyzed that old age, smoking, comorbid status, low SpO2, longer hospitalization, lymphopenia, and increased severity of COVID-19 disease were independent risk factors for the development of pulmonary fibrosis in post-COVID-19 pneumonia. Conclusions: A better understanding of the underlying mechanism and pathogenesis can help in filling up of gaps in risk stratification of COVID-19.

A quantitative analysis of long-term follow-up computed tomography of idiopathic pulmonary fibrosis: the correlation with the progression and prognosis.

Quantitative analyses of computed tomography (CT) images using computer-aided detection (CAD) are correlated with visual assessments and pulmonary function test findings and might be useful for predicting the prognosis of patients with idiopathic pulmonary fibrosis (IPF). To evaluate the association between the quantitative analysis of long-term follow-up CT of IPF and the progression and prognosis. A total of 48 patients with IPF who received over one year of follow-up CT were included in this study. The results of quantitative analyses (emphysema, ground-glass attenuation [GGA], consolidation, reticulation, and honeycombing) using a CAD software program of initial and follow-up CT findings were evaluated, and the association with the progression of the total lesion of IPF and prognosis using Spearman's rank correlation and Cox regression analyses was considered. Results of quantitative analyses of consolidation, reticulation, honeycombing, and the total lesion on initial CT were correlated with progressive changes in the total lesion of IPF per year (r = 0.4375, 0.4128, 0.4649, and 0.4095, respectively). The results of quantitative analyses of honeycombing (hazard ratio [HR] = 1.40, 95% confidence interval [CI] = 1.03-1.89, P = 0.0314) and GGA (HR = 0.85, 95% CI = 0.72-0.99, P = 0.0384) at initial CT were prognostic factors according to a multivariate Cox regression analysis. The quantitative analysis of honeycombing using a CAD software program of CT findings may be useful for predicting the progression and prognosis of patients with IPF.

One-year follow-up CT findings in COVID-19 patients: A systematic review and meta-analysis.

Coronavirus disease 2019 (COVID‐19) often causes radiological and functional pulmonary sequelae. However, evidence on 1‐year follow‐up of pulmonary sequelae is limited. We aimed to investigate the characteristics and time‐course of pulmonary sequelae after recovery from COVID‐19 through 1‐year follow‐up. We searched PubMed and EMBASE databases on 25 February 2022, and included studies with computed tomography (CT) findings at the 1‐year follow‐up. The extracted data on CT findings were analysed using a one‐group meta‐analysis. We further analysed the data in relation to COVID‐19 severity, improvement rate and lung function. Fifteen eligible studies (N = 3134) were included. One year after COVID‐19, 32.6% (95% CI 24.0–42.6, I 2 = 92.9%) presented with residual CT abnormalities. Ground‐glass opacity and fibrotic‐like changes were frequently observed in 21.2% (95% CI 15.4–28.4, I 2 = 86.7%) and 20.6% (95% CI 11.0–35.2, I 2 = 91.9%), respectively. While the gradual recovery was seen on CT (52.9% [mid‐term] vs. 32.6% [1 year]), the frequency of CT abnormalities was higher in the severe/critical cases than in the mild/moderate cases (37.7% vs. 20.7%). In particular, fibrotic changes showed little improvement between 4–7 months and 1 year after COVID‐19. Pulmonary function tests at 1 year also showed the decline in diffusing capacity of the lung for carbon monoxide, especially in severe/critical cases. Our meta‐analysis indicated that residual CT abnormalities were common in hospitalized COVID‐19 patients 1 year after recovery, especially fibrotic changes in severe/critical cases. As these sequelae may last long, vigilant observations and longer follow‐up periods are warranted.

Computed Tomography in Adults with Bronchiectasis and Nontuberculous Mycobacterial Pulmonary Disease: Typical Imaging Findings

Among patients with bronchiectasis, nontuberculous mycobacterial pulmonary disease (NTM-PD) ranged between 1 and 6% and it is suspected that its prevalence is underestimated. Our aim was to evaluate differences in computed tomography (CT) features in patients with bronchiectasis, with and without NTM-PD, in order to facilitate earlier diagnosis in the future. In addition, we evaluated longitudinal changes after successful NTM-PD treatment. One hundred and twenty-eight CTs performed in adults with bronchiectasis were scored for the involvement, type, and lobar distribution of bronchiectasis, bronchial dilatation, and bronchial wall thickening according to Reiff. In addition, associated findings, such as mucus plugging, tree-in-bud, consolidations, ground-glass opacities, interlobular thickening, intralobular lines, cavities, and atelectasis, were registered. Patients with NTM-PD (n = 36), as defined by ATS/IDSA diagnostic criteria, were compared to bronchiectasis patients without NTM-PD (n = 92). In twelve patients with an available consecutive CT scan after microbiological cure of NTM-PD imaging findings were also scored according to Kim and compared in the course. In patients with NTM-PD, there was a higher prevalence of bronchiectasis in the middle lobes (p < 0.001), extended bronchiolitis (p = 0.032) and more small and large nodules (p < 0.001). Furthermore, cavities turned out to be larger (p = 0.038), and walls thickened (p = 0.019) and extended (p = 0.016). Patients without NTM more often showed peripheral ground-glass opacities (0.003) and interstitial changes (p = 0.001). CT findings decreased after successful NTM-PD treatment in the follow-up CT; however, without statistical significance for most features (p = 0.056), but bronchiolitis was the only significantly reduced score item (p = 0.043). CT patterns in patients with bronchiectasis and NTM-PD differ from those of patients with bronchiectasis without NTM-PD, although the findings are non-specific radiological features. Follow-up CT findings after microbiological cure differed interindividual regarding the decline in imaging features. Our findings may help practitioners to identify NTM-PD in patients with bronchiectasis. Further research is needed regarding the use of CT as a potential imaging biomarker for the evaluation of treatment response.

Chest computed tomography imaging features in patients with coronavirus disease 2019 (COVID-19).

ObjectiveTo analyze computed tomography (CT) features of symptomatic patients with coronavirus disease 2019 (COVID-19).MethodsNinety-five symptomatic patients with COVID-19 confirmed by reverse-transcription polymerase chain reaction from 1 May to 14 July 2020 were retrospectively enrolled. Follow-up CT findings and their distributions were analyzed and compared from symptom onset to late-stage disease.ResultsAmong all patients, 15.8% had unilateral lung disease and 84.2% had bilateral disease with slight right lower lobe predilection (47.4%). Regarding lesion density, 49.4% of patients had pure ground glass opacity (GGO) and 50.5% had GGO with consolidation. Typical early-stage patterns were bilateral lesions in 73.6% of patients, diffuse lesions (41.0%), and GGO (65.2%). Pleural effusion occurred in 13.6% and mediastinal lymphadenopathy in 11.5%. During intermediate-stage disease, 47.4% of patients showed GGO as the disease progressed; however, consolidation was the predominant finding (52.6%).ConclusionCOVID-19 pneumonia manifested on lung CT scans with bilateral, peripheral, and right lower lobe predominance and was characterized by diffuse bilateral GGO progressing to or coexisting with consolidation within 1 to 3 weeks. The most frequent CT lesion in the early, intermediate, and late phases was GGO. Consolidation appeared in the intermediate phase and gradually increased, ending with reticular and lung fibrosis-like patterns.

Differences in the Clinical and Hematological Characteristics of COVID-19 Patients with and without Type 2 Diabetes.

Objective To examine whether comorbidity with type 2 diabetes (T2D) affects the clinical and hematological parameters of coronavirus disease 2019 (COVID-19) patients. Methods We retrospectively investigated the clinical, imaging, and laboratory characteristics of patients with confirmed COVID-19 who were hospitalized from January 30, 2020 to March 17, 2020, at the Renmin Hospital of Wuhan University. A detailed clinical record was kept for each subject, including the medical history of COVID-19 and physical and laboratory examinations. A total of 164 subjects were eligible for the study, among which 40 patients were comorbid with T2D. Further analysis was conducted in two subcohorts of sex- and age-matched patients with and without T2D to identify hematological and biochemical differences. The laboratory tests, including routine blood tests, serum biochemistry, and coagulation function, were performed upon admission. Results The two groups showed no significant differences in baseline parameters, including age, sex, chest X-ray, or computed tomography (CT) findings, upon admission. However, patients with T2D showed an increased incidence of diarrhea. T2D patients required more recovery time from pneumonia, as shown by follow-up CT findings, which might contribute to the prolonged hospitalization. Comorbidity with T2D also increased risk of secondary bacterial infection during COVID-19. The T2D group had significantly higher white blood cell and neutrophil counts compared with the nondiabetic group, but T2D patients suffered from more severe lymphocytopenia and inflammation (P < 0.05). Most biochemical parameters showed no significant differences between the two groups (P > 0.05). However, patients with T2D seemed to have a significantly higher risk of developing hyperlactatemia, hyponatremia, and hypocalcemia. Conclusions COVID-19 patients comorbid with T2D demonstrated distinguishing clinical features and hematological parameters during the infection. It is necessary to develop a different clinical severity scoring system for COVID-19 patients with T2D. This study may provide helpful clues for the assessment and management of COVID-19 in T2D patients.

Retrograde Drilling for Osteochondral Lesions of the Talus in Skeletally Immature Children

Osteochondral lesions of the talus (OLTs) involve damage to the cartilage and subchondral bone and are infrequent in children. Clinicians usually attempt nonsurgical treatment of OLTs first, and subsequently progress to surgical treatments, including retrograde drilling (RD), if the initial outcomes are insufficient. Good clinical outcomes of RD have been reported. However, the clinical outcomes of RD in skeletally immature children remain unclear, and the associated preoperative and postoperative computed tomography (CT) findings have not been reported. The purpose of this study was to evaluate the clinical outcomes and CT findings and clarify the efficacy of RD for OLTs. From January 2015 to April 2018, RD was performed on 8 ankles in 6 skeletally immature children. The patients comprised 4 boys and 2 girls with a mean age at surgery of 11.1 years. The mean follow-up was 22.8 months. The clinical outcomes were evaluated according to the Japanese Society for Surgery of the Foot (JSSF) scale. Preoperative and final follow-up CT findings were used to determine the degree of healing. The mean JSSF scale in all ankles improved from 79.4 (range, 69-90) points preoperatively to 98.4 (range, 87-100) points at final follow-up (P < .05). In the preoperative CT findings, 3 ankles had no bone fragmentation, 4 had partial bone fragmentation, and 1 had whole fragmentation. In the final follow-up CT findings, 4 ankles demonstrated good healing, 3 were fair, and 1 was poor. The present findings suggest that RD is an effective surgical treatment for OLTs in skeletally immature children. Level IV, retrospective case series.

Optimal Treatment Strategy and Natural History of Isolated Superior Mesenteric Artery Dissection Based on Long-Term Follow-up CT Findings

Isolated superior mesenteric artery dissection (ISMAD) was previously considered a rare disorder; however, this condition has been increasingly diagnosed as time progressed. Although treatment regimen and treatment outcomes have become clearer, the optimal treatment strategy has not yet been well established. This study included 54 patients diagnosed with ISMAD by computed tomography (CT) between November 2004 and December 2017. Thirteen patients were excluded from the analysis of natural course as 6 were lost to follow-up, and 7 underwent endovascular therapy. Of the 54 patients included in the study, 50 were male, and 4 were female. The mean age of the patients was 52.3years (range 40-74). The mean follow-up duration was 18.5months (range 1.0-131.0). Thirty-eight patients were symptomatic, and 16 were asymptomatic. All aneurysmal changes observed on follow-up CT scans were initially classified as type III or IV. Of these patients, 7 underwent endovascular therapy. The failure rate of conservative treatment was 13%. Conservative treatment is safe and effective if bowel necrosis or arterial rupture is not present. Symptomatic patients classified as type III or IV on the initial CT scan should be followed up. If there is recurrent pain or aneurysmal progression, endovascular therapy should be performed.

Endoscopic Ultrasound-Guided Drainage without Fluoroscopic Guidance for Extraluminal Complicated Cysts.

Background. Endoscopic ultrasound- (EUS-) guided drainage is generally performed under fluoroscopic guidance. However, improvements in endoscopic and EUS techniques and experience have led to questions regarding the usefulness of fluoroscopy. This study aimed to retrospectively evaluate the safety and efficacy of EUS-guided drainage of extraluminal complicated cysts without fluoroscopic guidance. Methods. Patients who had undergone nonfluoroscopic EUS-guided drainage of extraluminal complicated cysts were enrolled. Drainage was performed via a transgastric, transduodenal, or transrectal approach. Single or double 7 Fr double pigtail stents were inserted. Results. Seventeen procedures were performed in 15 patients in peripancreatic fluid collections (n = 13) and pelvic abscesses (n = 4). The median lesion size was 7.1 cm (range: 2.8–13.0 cm), and the mean time spent per procedure was 26.2 ± 9.8 minutes (range: 16–50 minutes). Endoscopic drainage was successful in 16 of 17 (94.1%) procedures. There were no complications. All patients experienced symptomatic improvement and revealed partial to complete resolution according to follow-up computed tomography findings. Two patients developed recurrent cysts that were drained during repeat procedures, with eventual complete resolution. Conclusion. EUS-guided drainage without fluoroscopic guidance is a technically feasible, safe, and effective procedure for the treatment of extraluminal complicated cysts.

DISTRIBUTION AND SHORT- AND LONG-TERM EFFECTS OF INJECTED GELIFIED ETHANOL INTO THE LUMBOSACRAL INTERVERTEBRAL DISC IN HEALTHY DOGS.

Radiopaque gelified ethanol preparation has been described as a useful agent for treatment of humans with intervertebral disc protrusion. The material is injected into the nucleus pulposus under image guidance with intention to cause the protruded disc material to recede. Because treatment options for dogs with chronic protrusions are limited, new and minimally invasive treatments are desirable. The aim of this experimental, descriptive, prospective study was to assess the feasibility and safety of percutaneous injection of gelified ethanol into the lumbosacral intervertebral disc of dogs. Lumbosacral intervertebral discs of normal dogs (n = 9) were imaged with magnetic resonance imaging and then injected with gelified ethanol using image guidance. The accuracy of gelified ethanol placement in the nucleus pulposus and presence of leakage of the injected material were documented. Postinjection computed tomography (CT) findings (n = 9), short-term (n = 9) and long-term (n = 4) follow-up magnetic resonance imaging and CT findings were compared to document the distribution of the injected preparation and identify effects on adjacent tissues. Percutaneous injection of the intervertebral disc was successful in delivering radiopaque gelified ethanol to the nucleus pulposus in all dogs. Leakage of the injected material into the vertebral canal was present in three dogs immediately following injection and in another additional dog at 1 year following injection. All dogs tolerated the injection well and had no clinical adverse reactions within the study period. Findings indicated that injection of the nucleus pulposus of healthy dogs was well tolerated, even in the presence of mild leakage of material from the intervertebral disc.

Post rtPA CT brain may not be mandatory in all stroke patients when resources are limited

Background: Routine neuroimaging of the brain is performed after recombinant-tissue-plasminogen activator (rtPA) treatment in patients with acute ischemic stroke. However, in situation where resources are limited, it is not known if a follow-up computed tomography (CT) is beneficial for guiding the treatment plan or not. The purpose of this study is to investigate the need for a follow-up CT in patients with acute stroke after rtPA treatment. Methods: Patients who were treated with intravenous rtPA were included. Clinical symptoms/signs of the patients were evaluated at 24h after rtPA treatment compared with baseline NIHSS. The need for a follow-up CT after rtPA treatment was assessed by comparison of the early clinical changes with the CT brain results that would affect the management plan: presence of hemorrhagic transformation, malignant MCA infarction, or large cerebellar infarction. Results: 200 patients were included. 19 patients (9.5%) had complete recovery. CT post rtPA revealed no change in these patients. In 105 patients who had early improvement with NIHSS of 1–10 at 24h, follow-up CT findings did not change the plan of management in 85%. Follow-up CTs may help in planning further management in 65% and 67% of the patients who had NIHSS>10 at 24h and early worsening, respectively. Conclusions: CT post rtPA may not be required in patients with early clinical recovery (NIHSS=0). However, in patients with residual severe deficit post rtPA or patients with early worsening or suspected posterior circulation stroke, CT post rtPA is still needed.

Bone and Soft-Tissue Sarcoma: Preoperative Staging with Fluorine 18 Fluorodeoxyglucose PET/CT and Conventional Imaging

To retrospectively compare the diagnostic accuracy of positron emission tomography (PET)/computed tomography (CT), PET, conventional imaging, and combined PET/CT and conventional imaging for tumor staging of bone and soft-tissue sarcomas, by using histologic or follow-up imaging findings as the reference standard. Institutional review board approval was received for this HIPAA-compliant study; informed consent was obtained. Integrated PET/CT was performed in 117 patients (69 male patients, 48 female patients; mean age, 42 years +/- 21 [standard deviation]; range, 9-86 years). Conventional imaging consisted of magnetic resonance imaging of the primary site, chest radiography, whole-body contrast material-enhanced CT, and bone scintigraphy. A total of four reviewers assessed all images. Overall and T staging were evaluated in 69 (59%) patients who underwent surgical removal of the primary tumors and had pathologically proved results. N and M staging were evaluated in all patients, and their reference methods were based on histologic findings (n = 101) and follow-up CT findings (n = 16). Interpretations based on combined PET/CT and conventional imaging findings correctly staged tumors in 60 (87%) of 69 patients, overstaged tumors in eight (12%) patients, and understaged tumors in one (1%) patient. Overall staging accuracy of combined PET/CT and conventional imaging was significantly higher than that at PET (P < .0001). Combined PET/CT and conventional imaging resulted in correct N staging in 114 (97%) of 117 patients and M staging in 109 (93%) of 117 patients. Combined PET/CT and conventional imaging helped reduce overstaging in three (4%) patients and helped change tumor diagnosis from unresectable to resectable in two (2%) patients compared with PET/CT. The combination of PET/CT and conventional imaging is accurate in preoperative staging of bone and soft-tissue sarcoma.

Invasive Carcinomas Derived From Intraductal Papillary Mucinous Neoplasms of the Pancreas

To describe computed tomography (CT) findings of invasive carcinoma derived from intraductal papillary mucinous neoplasms (IPMNs) of the pancreas during long-term follow-up. Follow-up CT findings of 5 patients with IPMNs progressing to invasive carcinomas were respectively reviewed for 12 to 63 months. All patients underwent thin-section 3-phase helical and/or multislice CT. Invasive carcinomas were detected as hypo- (n = 3) or hyperattenuating (n = 2) solid masses in the pancreatic parenchyma on contrast-enhanced CT. Hypoattenuating masses were mostly visualized on arterial dominant phase images. In 4 branch-duct type IPMNs, the solid masses appeared with (n = 3) or without (n = 1) dilatation of the main pancreatic duct after 3 to 5 years. In the remaining combined-type IPMN, a solid mass was detected on initial CT and progressively increased during the follow-up. Arterial dominant phase CT is useful for detecting invasive carcinoma derived from IPMNs and is an effective follow-up method.

Follow-up CT findings of tamoxifen-induced non-alcoholic steatohepatitis (NASH) of breast cancer patients treated with bezafibrate

One-third of the breast cancer patients who underwent tamoxifen intake showed less than 0.9 of their liver/spleen CT (computed tomography) ratio on their annual CT study, and were diagnosed as having fatty liver (hepatic steatosis). Among them, patients who showed a lower liver/spleen CT ratio of less than 0.5 were recommended to undergo needle biopsy of the liver in order to obtain histopathological confirmation of non-alcoholic steatohepatitis (NASH), with 15 patients undergoing needle biopsy of the liver. As a result, 14 out of the 15 patients were diagnosed as having NASH, and these patients were additionally administered bezafibrate in order to prevent possible progressive changes of NASH into liver cirrhosis. In this study, we show the changes of follow-up CT findings of 6 patients with histopathologically-proven NASH who continued to undergo bezafibrate intake after the diagnosis of NASH. Two patients showed almost complete improvement as indicated by the liver/spleen CT ratio several months after completion of a tamoxifen intake of 5 years, and another 3 showed partial improvement on their liver/spleen CT ratio by bezafibrate intake in spite of continuing tamoxifen intake. Another patient with diabetes mellitus (type II) showed a continually decreasing liver/spleen CT ratio during adjuvant tamoxifen in spite of bezafibrate intake. Therefore, we concluded that the progression of NASH could be prevented by bezafibrate without any interruption of adjuvant tamoxifen treatment. For patients with diabetes mellitus, critical follow-up using CT study and laboratory tests is considered essential.

Descending thoracic aortic aneurysm: thoracic CT findings after endovascular stent-graft placement.

To evaluate the usefulness of thoracic computed tomography (CT) after placement of an endovascular stent-graft for the treatment of descending thoracic aortic aneurysm. From 1992 to 1996, 85 patients with thoracic aortic aneurysm underwent stent-graft placement. In 63 patients, thoracic CT scans were obtained both before and within 10 days after placement. The CT findings were retrospectively studied, and their clinical effect analyzed. In 20 of 63 patients, long-term follow-up CT findings were also evaluated. After stent-graft placement in the 63 patients, CT demonstrated an increase in pleural effusion in 46 (73%), periaortic changes in 21 (33%), perigraft leak in 13 (21%), atelectasis in six (10%), mural thrombus within the stent-graft in two (3%), and new aortic dissection in one (2%). The mean maximum diameter of the aneurysm was 58.8 mm before and 60.0 mm after stent-graft insertion. Sixty-two (98%) patients were successfully treated until discharge. Interventional procedures were performed to eliminate the leakage into the aneurysm sac in 10 patients with perigraft flow depicted at CT. Other complications were managed conservatively. Thoracic CT is useful in the treatment of patients after stent-graft insertion for the management of descending thoracic aortic aneurysm.

Perfusion CT of the brain: diagnostic approach for early detection of ischemic stroke.

To determine the value of perfusion computed tomography (CT) in a clinical study of patients with stroke and compare the results with single photon emission CT (SPECT) findings. Perfusion CT was performed within 6 hours of symptom onset in 32 patients with possible stroke. Cerebral blood volume (CBV), cerebral blood flow (CBF), and time to peak contrast material enhancement were calculated on the basis of the CT results. Cerebral SPECT was also performed in a subgroup of 18 patients. Perfusion CT and SPECT findings were compared in a lesion-by-lesion analysis. Perfusion CT results were compared with follow-up CT and magnetic resonance imaging findings. Areas of reduced CBF were detected with the aid of perfusion CT in 25 of 28 patients with a proved infarct (sensitivity, 89%). The results of the CBF maps corresponded well to SPECT findings in 13 (81%) of 16 patients, but ischemia was located outside the scanning level in the other three patients and was therefore missed. Perfusion CT revealed various changes in CBF, CBV, and time to peak enhancement in ischemic territories. Perfusion CT not only allows early detection of cerebral ischemia but also yields valuable information about the extent of perfusion disturbances.

Acute occlusion of the middle cerebral artery: early evaluation with triphasic helical CT--preliminary results.

To evaluate use of triphasic helical computed tomography (CT) for early diagnosis of occlusion and assessment of ischemia in cases of acute middle cerebral arterial occlusion. Thirty-five patients with acute ischemia underwent triphasic helical CT within 6 hours after symptom onset. Early arterial, perfusion, and delayed phase CT scans were obtained 18, 30, and 80 seconds, respectively, after contrast material administration. Eighteen patients had proximal middle cerebral arterial occlusion diagnosed at magnetic resonance (MR) or digital subtraction angiography. Follow-up CT or MR imaging was performed in all patients. Two independent observers interpreted images for signs of arterial occlusion, collateral vessels, and the ischemic zone. One observer found at least one of three signs in 17 of the 18 patients with occlusion, and the other found at least one sign in all 18: Early decreased arterial contrast enhancement was seen by both observers in 11 patients (kappa = 0.77), a nonenhancing arterial segment was seen by the two observers in 12 and 14 (kappa = 0.73), and delayed asymmetric arterial enhancement was seen in 13 and 16 (kappa = 0.49). Triphasic CT findings of the ischemic zone were consistent with follow-up CT or MR imaging findings in seven of 12 patients. Triphasic helical CT is useful for early diagnosis of acute proximal middle cerebral arterial occlusion and assessment of the ischemic zone.

Amino Acid Study of Cerebral Gliomas Using Positron Emission Tomography

Sixteen patients with gliomas (7 low grade, 9 high grade) were examined using positron emission tomography (PET) with intravenous administration of 22.2 MBq/kg (0.6 mCi/kg) of (11C-methyl)-L-methionine (C-11 Met). The tracer uptake in regions of interest was calculated on PET images taken 45 minutes after injection; the uptake index was represented as a percentage of the total count in the arterial blood summed over 45 minutes. C-11 Met uptake indices in the tumors ranged from 0.020 to 0.041% with a mean of 0.032% for the low-grade gliomas and from 0.013 to 0.044% with a mean of 0.036% for the high-grade gliomas. These indices significantly increased as compared with those in the contralateral gray matter (0.008-0.032% with a mean of 0.023%; p less than 0.01 vs. low-grade gliomas, p less than 0.001 vs. high-grade gliomas). In the low-grade gliomas, C-11 Met PET images clearly depicted the existence and even the extent of the tumors, although x-ray computed tomography (CT) did not always distinguish tumoral lesions. In the high-grade gliomas, the areas of tracer accumulation regionally extended to peritumoral low density on CT scans, where malignant tumor cell infiltration was proved by operative and follow-up CT findings. C-11 Met may be a useful radiopharmaceutical for differential diagnosis of gliomas, and the accuracy of tumor localization will give us a better rationale in therapeutic strategies for surgery and radiation therapy of gliomas.