Tangent vector-based gradient method with l12-regularization: Iterative half thresholding algorithm for CS-MRI

OBJECT

This paper presents a new method using tangent vector-based l₁₂-regularization for compressed sensing MR image reconstruction.

MATERIALS AND METHODS

The proposed method with l₁₂-regularization is tested on four datasets: (i) 1-D sparse signal (ii) numerical cardiac phantom, (iii & iv) two sets of in-vivo cardiac MRI datasets acquired using 30 receiver coil elements with Cartesian and radial trajectories on 3T scanner. The results are compared with standard CS reconstruction, which utilizes l₁-regularization. The experiments were also conducted for two different types of samplings: (i) cartesian sub-sampling and (ii) 2D random Gaussian sub-sampling.

RESULTS

The quality of the reconstructed images is validated through Root Mean Square Error (RMSE) and Peak Signal-to-Noise Ratio (PSNR). The results show that the proposed method outperforms the standard CS reconstructions in our experiments with an improvement of 54.8% in RMSE and 14.3% in terms of PSNR. Moreover, the Gaussian random sub-sampling-based image reconstruction results are better than the Cartesian sub-sampling-based reconstruction results.

CONCLUSION

The results show that the proposed method yields a good sparse signal approximation and superior convergence behavior, which implies a promising technique for the reconstruction of cardiac MR images as compared to the conventional CS algorithm.

Response to cotrimoxazole in the management of childhood pneumonia in first-level health care facilities

BACKGROUND

Reports of high levels of antimicrobial resistance to cotrimoxazole in children with non-severe pneumonia (NSP) have prompted calls for a change to amoxicillin in the therapeutic guidelines at the first-level health care facility (FLHF). FLHFs lack data about the use of World Health Organization (WHO) acute respiratory infection (ARI) standard case management (SCM).

OBJECTIVE

To apply ARI SCM guidelines at the FLHF, assess clinical outcome of NSP with oral cotrimoxazole and determine the risk factors influencing treatment outcome.

DESIGN

Health care workers (HCWs) at 14 health centres managed children aged 2-59 months with NSP according to ARI SCM guidelines. The primary outcome was treatment failure, including change of antibiotic therapy and loss to follow-up.

RESULTS

Of 949 children enrolled, 110 (11.6%) failed therapy with oral cotrimoxazole. Clinical failure was significantly higher among children presenting with a fast respiratory rate of > or = 15 breaths/min above normal for age and wheezing on examination.

CONCLUSIONS

To treat children with NSP at the FLHF, oral cotrimoxazole is an acceptable treatment choice in view of the efficacy, cost and ease of use. In children with wheezing and signs of pneumonia, the decision to use antibiotic therapy should be made after a trial of bronchodilator therapy.

Can WHO therapy failure criteria for non-severe pneumonia be improved in children aged 2-59 months?

SETTING

In the recent past, there have been reports of rising treatment failure rates for non-severe pneumonia. It is felt that World Health Organization (WHO) criteria for therapy failure are too sensitive and that many children are unnecessarily classified as failures. We studied alternative, less sensitive therapy failure criteria.

METHODS

In this nested study we followed the clinical course of non-severe pneumonia in children aged 2-59 months using alternative therapy failure criteria. All children received amoxicillin and were followed up on days 3, 5 and 14 after enrollment. On day 3, children were labelled as therapy failure only if their condition had deteriorated. These failure rates were compared with those using WHO definitions.

RESULTS

During the study period, 876 children with non-severe pneumonia were followed up until day 14. On day 3, using alternative therapy failure criteria, 31 (3.5%) children were labelled as therapy failure compared to 95 (10.8%) using current WHO criteria. The difference was statistically significant (P = 0.001).

CONCLUSIONS

The alternative therapy failure criteria work reasonably well, without causing any higher risk to children with non-severe pneumonia. Antibiotics should be changed only in those children who show signs of deterioration on day 3. This would prevent unnecessary changes in antibiotic treatment in many children.

Therapeutic re-appraisal of multiple drug resistant Salmonella typhi (MDRST) in Pakistani children

BACKGROUND

The emergence of multi drug-resistant Salmonella typhi (MDRST) in many developing countries including Pakistan, has led to a search for suitable alternatives to conventional therapy. Quinolones have been found to be an effective alternative for the treatment of MDRST, in adults as well as in children.

METHODS

The efficacy of various therapeutic regimens currently used for the treatment of Typhoid was analysed. Children 1 month to 12 years of age admitted to the Children's Hospital from 1990 to 1993 with fever and Salmonella typhi isolated from blood cultures were included in this retrospective analysis.

RESULTS

The cumulative prevalence of Multiple Drug Resistant Salmonella typhi (MDRST) was 67.2%. Only 32.8% of isolated Salmonella typhi were susceptible to chloramphenicol and amoxicillin. The cumulative cure rate with conventional therapy (chloramphenicol or amoxicillin) was 47.4% and 53.6% children needed a change of therapy. The average hospital stay for the non-responders to conventional therapy was 9.2 days as compared to 7.7 days for the responders. The average hospital stay of the patients treated with a third generation cephalosporin was 12.7 days. Patients treated with ofloxacin, a flouroquinolone drug, did not need a change of therapy. The average hospital stay of the patients treated with flouroquinolones was 6.2 days.

CONCLUSION

There was a high prevalence of multiple drug resistant typhoid fever in hospitalized children, leading to a high failure rate with conventional therapy. This resulted in frequent change of therapy, delayed defervesence and prolonged hospital stay. The flouroquinolones were found to be the most effective drug against MDRST.

Antibiotic strategies for developing countries: experience with acute respiratory tract infections in Pakistan

The Pakistan program for control of acute respiratory tract infections (ARIs) adopted the standard ARI-case-management strategy of the World Health Organization and recommended co-trimoxazole for the management of nonsevere pneumonia. Reports in that country of high in vitro antimicrobial resistance of Streptococcus pneumoniae and Haemophilus influenzae to co-trimoxazole prompted the program to reevaluate its treatment policy. Two community-based studies during 1991-1993 showed in vivo efficacy of co-trimoxazole in 92% and 91% of children with nonsevere pneumonia. A third double-blind trial showed co-trimoxazole and oral amoxicillin to be equally effective in vivo in cases of nonsevere pneumonia, despite high in vitro resistance. Country-wide surveillance from 1991 to 1994 revealed 78.3%-79.9% in vitro resistance to co-trimoxazole among S. pneumoniae isolates and 59.5%-61.0% among H. influenzae isolates. Co-trimoxazole is still recommended by the Pakistan ARI control program. The fact that amoxicillin is three times more expensive and must be administered more frequently is a big impediment to recommending it as a first-line drug for nonsevere pneumonia.

Antimicrobial resistance and clinical effectiveness of co-trimoxazole versus amoxycillin for pneumonia among children in Pakistan: randomised controlled trial. Pakistan Co-trimoxazole Study Group

BACKGROUND

Co-trimoxazole is widely used in treatment of paediatric pneumonia in developing countries, but drug resistance may decrease its effectiveness. We studied the effectiveness of co-trimoxazole compared with that of amoxycillin in pneumonia therapy, and assessed the clinical impact of co-trimoxazole resistance.

METHODS

We recruited 595 children, aged 2-59 months, with non-severe or severe pneumonia (WHO criteria) diagnosed in the outpatient wards of two urban Pakistan hospitals. Patients were randomly assigned on a 2:1 basis co-trimoxazole (n=398) or amoxycillin (n=197) in standard WHO doses and dosing schedules, and were monitored in study wards. The primary outcome was inpatient therapy failure (clinical criteria) or clinical evidence of pneumonia at outpatient follow-up examination.

FINDINGS

There were 92 (23%) therapy failures in the co-trimoxazole group and 30 (15%) in the amoxycillin group (p=0.03)-26 (13%) versus 12 (12%) among children with non-severe pneumonia (p=0.856) and 66 (33%) versus 18 (18%) among those with severe pneumonia (p=0.009). For patients with severe pneumonia, age under 1 year (p=0.056) and positive chest radiographs (p=0.005) also predicted therapy failure. There was no significant association between antimicrobial minimum inhibitory concentration and outcome among bacteraemic children treated with co-trimoxazole.

INTERPRETATION

Co-trimoxazole provided effective therapy in non-severe pneumonia. For severe, life-threatening pneumonia, however, co-trimoxazole is less likely than amoxycillin to be effective.

Epidemiology of childhood tuberculosis in a hospital setting

A study of two hundred cases of tuberculosis over a span of two years was carried out at the pediatric department of a hospital in Islamabad. The diagnosis was based upon history, clinical examination, chest and other relevant radiography, Mantoux test, erythrocyte sedimentation rate (ESR) and where necessary cerebrospinal, pleural and ascitic fluid examinations and lymph gland histopathology were done. An equal number of male and female children upto 12 years of age were enrolled. The children usually presented with fever, cough, weight loss or failure to thrive and pallor. The most commonly affected age group was between 2-5 years and pulmonary tuberculosis was the most frequent diagnosis followed by tuberculous adenitis.

Epidemiology of childhood tuberculosis in a hospital setting

Two hundred paediatric cases of tuberculosis were studied over two years. The children usually presented with fever, cough, weight loss or failure to thrive and pallor. The diagnosis was based on history, clinical examination, chest and other relevant radiographs, Mantoux test, erythrocyte sedimentation rate (ESR) and where necessary cerebrospinal, pleural and ascitic fluid examinations and lymph gland histopathology were done. The most commonly affected age group was between 2-5 years and pulmonary tuberculosis was the most frequent diagnosis followed by tuberculous adentitis.

Congenital hematometrocolpos in a circumcised girl. An anomaly superimposed by cultural mutilating practices

A rare case associated with congenital hematometrocolpos in a circumcised 13 years old Somalian girl is presented. Emphasis on proper history is highlighted. Mutilation caused by bad cultural practice of female circumcision which is although not a problem in Pakistan, is brought into notice for those who may be unaware of perineal appearance of a circumcised female and stitched over vagina.

Dexamethasone and bacterial meningitis in Pakistan

The objective of this study was to assess, in a developing country setting, the effect of dexamethasone therapy on bacterial meningitis outcomes. A prospective double blind placebo controlled trial was conducted in 89 children aged from 2 months to 12 years suffering from bacterial meningitis. Neurological, developmental, and hearing assessments were conducted at one, four, and 12 months after discharge. Forty eight patients received dexamethasone and 41 placebo. Initial antimicrobial drugs used were ampicillin and chloramphenicol. For all patients at the time of admission the mean duration of illness was 5.7 days; 47% had had seizures and 56% had impaired consciousness. Seventeen of 89 (19%) patients died. The mortality for the dexamethasone group was 25% as compared with 12% in the group receiving placebo. Presentation to the hospital after four days of symptoms and with impaired conscious state were independent predictors of death. Of the dexamethasone group survivors, 26.5% had neurological sequelae and 42.3% had hearing impairment, whereas in the placebo group it was 24% and 30% respectively. Altered state of consciousness was a predictor of neurological sequelae. The presence of neurological sequelae and high cerebrospinal fluid protein independently predicted hearing loss. No beneficial effect of dexamethasone was observed on morbidity or mortality of this group of patients with bacterial meningitis. Dexamethasone is therefore not useful in developing countries as adjunctive treatment in patients seriously ill with bacterial meningitis, who present late for treatment and have been partially treated.

Clinical, nutritional and radiological features of pneumonia

From December, 1992 to February, 1993, 100 consecutively admitted children between 2-24 months of age with pneumonia were studied. They were diagnosed and treated according to the National ARI Control Programme case management guidelines. Of the total, 74 were under one year of age. Seventeen children had very severe pneumonia, 77 severe pneumonia and 6 simple pneumonia. Sixty children had radiological evidence of pneumonia, 89 responded to standard recommended treatment and only 11% required a change of therapy. There were no deaths. Only 6 mothers of these 100 children had practiced exclusive breast feeding. Low socioeconomic status, illiteracy and malnutrition were the other risk factors. In this study all types of pneumonia were more common in children under one year of age and radiology did not appear to be essential for its diagnosis. The National ARI Control guidelines for diagnosis and management of hospitalized children are simple, useful and effective.

Standard management of acute respiratory infections in a children's hospital in Pakistan: impact on antibiotic use and case fatality

Acute respiratory infections (ARI) are a leading cause of childhood morbidity and mortality in Pakistan. The National ARI Control Programme was launched in 1989 in order to reduce the mortality attributed to pneumonia, and rationalize the use of drugs in the management of patients with ARI. WHO's standard ARI case management guidelines were adopted to achieve these objectives. The medical staff at the Children's Hospital, Islamabad, were trained in such management in early 1990; further training sessions were conducted when new staff arrived. Data on outpatients were obtained from special ARI abstract registers, which have been maintained in the outpatient department since January 1990. Details on inpatients who were admitted with ARI were obtained from hospital registers. During the period 1989-92, the use of antibiotics in the outpatient department decreased from 54.6% to 22.9% (P < 0.0001). The case fatality rate (CFR) in children admitted with ARI fell from 9.9% to 4.9% (P < 0.0001), while the overall case fatality rate fell from 8.7% to 6.2%. Our results from a tertiary health care facility show that standard ARI case management reduced both antibiotic use and expenditure on drugs. Although the ARI case management criteria, which are more sensitive than the conventional diagnostic criteria of auscultation and radiography, led to more admissions, we believe that this strategy contributed to a significant reduction in the ARI case fatality rate.

ARI concepts of mothers in Punjabi villages: a community-based study

Pneumonia is a major child killer in the developing world; to prevent such deaths, mothers must be able to differentiate pneumonia from common cold. Local concepts regarding these illnesses were studied by interviewing 315 mothers of young children in their homes in Punjabi villages. Mothers described pneumonia differently from cough-and-cold but only a few volunteered fast breathing as a sign of pneumonia. Both illnesses were thought to be caused by "coldness," and were initially treated with "heat-producing" home remedies and feeding was continued in both. Spiritual healers were not consulted for cough-and-cold or pneumonia. Virtually all mothers said that allopathic medicines were necessary for both illnesses and 2/3rd said that if a child did not improve after 2 days of a given medicine, they would change the medicine and/or the doctor.

A community study of the application of WHO ARI management guidelines in Pakistan

During a community-based study in four rural villages in Pakistan, 617 cases of acute respiratory infections (ARI) in children younger than 5 years of age were assessed, classified and managed according to the WHO ARI case management guidelines. Of these, 509 (82.5%) had 'cough and cold' without clinical evidence of pneumonia, 95 pneumonia, two severe pneumonia and 11 otitis media. Of the 509 without clinical evidence of pneumonia but with cough and cold, 491 (96.5%) were successfully treated without antibiotics and only 18 (3.5%) of these children needed antimicrobial therapy on follow-up. Of the 95 cases of pneumonia, 87 (91.4%) showed a satisfactory clinical response to oral cotrimoxazole and only eight (8.4%) required a change of antibiotic.

The Rett syndrome: the first case report from Pakistan

We report an 11-yr-old girl who visited the outpatient department of Islamabad Children's Hospital with uncontrolled seizures, psychomotor retardation and hand washing movements since early childhood. She had an uneventful peri- and neonatal history with a normal head size at birth and fulfilled the criteria of classic Rett syndrome. This is the first report of the Rett syndrome in Pakistan.

Halofantrine hydrochloride--efficacy and safety in children with acute malaria

Thirty two children with symptomatic malaria due to P. vivax and P. Falciparum infections were treated with three doses of Halofantrine hydrochloride 8 mg/kg body weight every 6 hours. Mean fever clearance was 30 hours (range 24-48 hours). No significant clinical or biochemical side effects were observed. Symptoms cleared rapidly. Halofantrine hydrochloride was found to be highly effective and appeared to have no side effects in children with acute malaria infections.

Neurology in Islamabad Children's Hospital--present status and problems

Pediatric neurologic disease is still progressive health problem in developing countries, Disorders of mental and motor development (34.8% of total 5234 neurological patients in 1988-89), seizure disorders (25.8%) and infections of the nervous system (18.9%) are the most common neurological problems in the Islamabad Children's Hospital (ICH), Pakistan. These figures differ from those in children's Hospitals in developed countries such as Japan. ICH needs to establish a good neurology department with better physiotherapy and rehabilitation centre, a workshop and a facilitated physiological laboratory. The global situation can be controlled by improving the basic life and fundamental factors to improve the hygiene and general health status of mothers and their children. The provision of rural rehabilitation services is also needed. Also international technical cooperation and support would be helpful.

Transabdominal gastro-oesophageal devascularization and oesophageal transection for bleeding oesophageal varices

Fifty consecutive unselected patients presenting with acute haematemesis and melaena from endoscopically confirmed bleeding oesophageal varices were treated by one-stage transabdominal oesophageal transection with gastro-oesophageal devascularization and splenectomy. According to Child's classification, 15 were Grade A, 29 Grade B and six Grade C. The mortality rate was 10 per cent. Postoperative complications included gastric fundal leak (4 per cent), pleural effusion (4 per cent), subphrenic abscess (2 per cent), atelectasis (2 per cent) and pneumothorax (2 per cent). Although five patients (10 per cent) complained of transient dysphagia during follow-up, only one (2 per cent) presented evidence of stricture at the site of oesophageal transection. Clinical encephalopathy was not present in the surviving patients in the postoperative period. No recurrence of bleeding has been recorded in the surviving patients over a follow-up period of 2-3 years.