Shanker Raja

The sensitivity and specificity of FDG PET in distinguishing recurrent brain tumor from radionecrosis in patients treated with stereotactic radiosurgery

Radiation necrosis and recurrent brain tumor have similar symptoms and are indistinguishable on both magnetic resonance imaging (MRI) and computed tomograph scans. 18F‐fluorodeoxyglucose (FDG) positron emission tomography (PET) has been proposed as a diagnostic alternative, particularly when co‐registered with MRI. We studied 47 patients with brain tumors treated with stereotactic radiosurgery and followed with FDG PET. For all tumor types, the sensitivity of FDG PET for diagnosing tumor was 75% and the specificity was 81%. For brain metastasis without MRI co‐registration, FDG PET had a sensitivity of 65% and a specificity of 80%. For brain metastasis with MRI co‐registration, FDG PET had a sensitivity of 86% and specificity of 80%. MRI co‐registration appears to improve the sensitivity of FDG PET, making it a useful modality to distinguish between radiation necrosis and recurrent brain metastasis.

Epilepsy Surgery in Infants

Purpose: We report 12 infants who had frontal (n = 3), temporal (n = 2), or temporoparieto‐occipital (n = 2) resection or functional hemispherectomies (n = 5) at age 2.5–29 (mean 15.3) months for catastrophic epilepsy due to focal cortical dysplasia (n = 5), Sturge‐Weber syndrome (n = 3), ganglioglioma (n = 3), or hemimegalencephaly (n = 1). Seizures began at 1 day to 14 months (mean, 4.0 months) after birth, occurred frequently (often many times per day, and were refractory to antiepileptic drugs. Patients were evaluated for surgery at 2.5–24 (mean 12.4) months of age. Seven patients had hemiparesis and eight had slowed cognitive development. Seizures were characterized by arrest or marked reduction of behavioral motor activity with unclear level of consciousness (n = 4, with temporal or temporoparietal EEG seizures), focal clonic activity (n = 3, with perirolandic EEG seizures), generalized tonic stiffening (n = 3, with temporoparieto‐occipital, parietal, or frontal EEG seizures), or infantile spasms and hypsarrhythmia (n = 2, with a frontal tumor or temporoparieto‐occipital cortical dysplasia).

Neocortical temporal FDG-PET hypometabolism correlates with temporal lobe atrophy in hippocampal sclerosis associated with microscopic cortical dysplasia

Summary:  Purpose: Medically intractable temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS), with or without cortical dysplasia (CD), is associated with atrophy of the hippocampal formation and regional fluorodeoxyglucose positron‐emission tomography (FDG‐PET) hypometabolism. The relation between areas of functional and structural abnormalities is not well understood. We investigate the relation between FDG‐PET metabolism and temporal lobe (TL) and hippocampal atrophy in patients with histologically proven isolated HS and HS associated with CD.

Laparoscopic anatrophic nephrolithotomy: Feasibility study in a chronic porcine model

PURPOSE Anatrophic nephrolithotomy performed via open surgery involves incising the renal parenchyma along an avascular plane to remove a large, complex renal stone. We determined the feasibility of performing laparoscopic anatrophic nephrolithotomy in a survival porcine model. Furthermore, we present a novel technique of creating a staghorn calculus in the porcine model. MATERIALS AND METHODS After developing the technique in 3 pigs the survival study was performed in 10 consecutive animals. The procedure comprised 2 aspects. 1) We developed an animal model for staghorn calculi by retrograde injection of polyurethane (Fomo Products, Inc., Norton, Ohio) into the renal pelvis through a ureteral catheter. For a 2-week period the staghorn calculus was allowed to create hydronephrosis. 2) Laparoscopic anatrophic nephrolithotomy was done, involving control of the renal artery and vein, in situ renal hypothermia with ice slush in 1 animal, lateral renal parenchymal incision, stone extraction and suture repair of the incised collecting system and renal parenchyma. RESULTS Synthetic stone formation and laparoscopic anatrophic nephrolithotomy were successful in all 10 animals, including 1 that underwent staged bilateral anatrophic nephrolithotomy. Mean operative time for anatrophic nephrolithotomy was 125 minutes. Mean blood loss was 68 cc and mean warm ischemia time was 30 minutes (range 23 to 39). A residual small pelvicaliceal calculus was noted postoperatively in the initial 3 cases only. Thereafter, routine intraoperative ultrasonography and flexible endoscopy were done for stone localization, resulting in a stone-free rate of 100% in all 7 remaining animals. Diethylenetriamine pentaacetic acid renal scans documented improvement in the glomerular filtration rate from a mean of 26.4 ml. per minute after stone creation and hydronephrosis to 54.8 ml. per minute 4 to 5 weeks after laparoscopic anatrophic nephrolithotomy. CONCLUSIONS Laparoscopic techniques can be applied to complex stone surgery such as anatrophic nephrolithotomy with encouraging surgical and functional outcomes. To our knowledge this report represents the initial study of in situ creation of experimental staghorn calculi and laparoscopic anatrophic nephrolithotomy performed completely intracorporeally in a chronic porcine model.

First Prize: Percutaneous Endopyeloplasty: A Novel Technique

Background and Purpose: Despite a 10% to 15% failure rate, endopyelotomy remains the treatment of choice for most patients with ureteropelvic junction (UPJ) obstruction. We present a novel technique of percutaneous endopyeloplasty, wherein a precise, full-thickness approximation of a standard longitudinal endopyelotomy incision is performed in a horizontal Heineke-Mikulicz fashion through the conventional solitary percutaneous tract via a nephroscope. We assess the feasibility and efficacy of percutaneous endopyeloplasty in a chronic porcine bilateral UPJ obstruction model and compare outcome data with those of conventional endopyelotomy and laparoscopic pyeloplasty. Materials and Methods: Partial UPJ obstruction was created in 20 kidneys (11 pigs) by laparoscopic ligation of the upper ureter over a 5F ureteral catheter. After development of hydronephrosis over a period of 4 to 6 weeks, percutaneous endopyeloplasty (N = 10), conventional percutaneous endopyelotomy (N = 5), or laparoscopic pyeloplasty (N =...

Epilepsy surgery in the setting of periventricular leukomalacia and focal cortical dysplasia

We report an infant who had successful epilepsy surgery for intractable infantile spasms in the setting of bilateral periventricular leukomalacia and remote germinal matrix hemorrhage. Although MRI gave evidence of a diffuse cerebral insult and EEG showed hypsarrhythmia, focal epileptogenicity was suggested by previous partial seizures with onset over the right temporoparietal-occipital region and PET hypometabolism in that same area. Right temporoparietal and lateral occipital resection at 15 months resulted in seizure freedom and dramatic developmental progress at 1-year follow-up. Histopathologic examination of resected tissue showed cortical dysplasia, possibly due to the same insult that also resulted in the bilateral periventricular leukomalacia. From an etiologic perspective, this is one of very few reported cases strongly implicating acquired focal cortical dysplasia in response to a prenatal insult. From a clinical perspective, the case illustrates that the spectrum of potential surgical candidacy in infants may be broader than usually suspected.

Ictal Urinary Urge: Further Evidence for Lateralization to the Nondominant Hemisphere

Summary:  Purpose: To determine the lateralizing value of ictal urinary urgency.

Usefulness of ictal and interictal 99mTc ethyl cysteinate dimer single photon emission computed tomography in patients with refractory partial epilepsy.

Summary: Purpose: Ictal perfusion single photon emission computed tomography (SPECT), using HMPAO, has been shown to localize epileptic foci in ∼90% of studies. Unfortunately, HMPAO decomposes rapidly, precluding the performance of ictal studies. Ethyl cysteinate dimer (ECD) is a SPECT perfusion agent recently approved by the Food and Drug Administration. After preparation, this compound is stable for ∼6 h. facilitating the performance of ictal studies.

Present assessment of myocardial viability by nuclear imaging

Prospective delineation of viable from nonviable myocardium in patients with coronary artery disease in an important factor in deciding whether a patient should be revascularized or treated medically. Two common techniques--single-photon emission computed tomography (SPECT) and positron-emission computed tomography (PET)--are used in nuclear medicine using various radiopharmaceuticals for the detection of myocardial viability in patients. Thallium-201 (201Tl) and technetium-99m (99mTc)-sestamibi are the common radiopharmaceuticals used in different protocols using SPECT, whereas fluoride-18 (18F)-fluorodeoxyglucose (FDG) and rubidium-82 (82Rb) are most widely used in PET. The SPECT protocols involve stress/redistribution, stress/redistribution/reinjection, and rest/redistribution imaging techniques. Many studies have compared the results of 201Tl and (99mTc)-sestamibi SPECT with those of FDG PET; in some studies, concordant results have been found between delayed thallium and FDG results, indicating that 201Tl, although considered a perfusion agent, shows myocardial viability. Discordant results in a number of studies have been found between sestamibi and FDG, suggesting that the efficacy of sestamibi as a viability marker has yet to be established. Radiolabeled fatty acids such as iodine-123 (123I)-para-iodophenylpentadecanoic acid and carbon-11 (11C)-palmitic acid have been used for the assessment of myocardial viability with limited success. 11C-labeled acetate is a good marker of oxidative metabolism in the heart and has been used to predict the reversibility of wall motion abnormalities. (18F)-FDG is considered the marker of choice for myocardial viability, although variable results are obtained under different physiological conditions. Detection of myocardial viability can be greatly improved by developing new equipment and radiopharmaceuticals of better quality.

Scintigraphic detection of post-pneumonectomy bronchopleural fistulae

Abstract. A total of 20 ventilation studies [16 with xenon-133 and four with technetium-99m diethylenetriamine pentaacetic acid (DTPA)] were performed in 11 patients with suspected post-pneumonectomy bronchopleural fistulae. The findings on the ventilation scan were correlated with bronchoscopy, taken as the gold standard for purposes of comparison. The sensitivity and specificity for 133Xe scans were 83% and 100% respectively, while the sensitivity for 99mTc-DTPA aerosol studies was poor at 0%. Special techniques for optimal visualization of the fistulae are enumerated.