Gout

Regarding Gout,

1. Involvement of axial skeleton is rare.
2. Radiological changes are seen in 1-2 years after first clinical symtpoms.
3. Joint space loss and periarticular osteopenia are commonly encountered.
4. Tophi typically intensely enhance following gadolinium.
5. On ultraound, 'double counter sign' is highly suggestive of gouty arthritis

Answers: T, F, F, T, T

Explanation: 

1. 1st MTPJ is the most common joint affected, followed by 1st IPJ and TMTJ. Lower limbs are more often affted than upper limbs. Feer, wrist and elbows are commonly affected. Axial skeleton is rarely affected. 
2. It takes 5-10 years to develop the radiological changes after first clinical symtpoms.
3. Punched out periarticular erosion with overhanging margins are hallmark of gouty arthritis. The joint spaces are preserved till late stage. Periarticular osteopenia is not a feature of gout. In late stages, diffuse osteopenia may be seen.
4. Tophi show low-to-intermediate signal on T1 and t2, and intensely enhance following contrast.
5. 'Double counter sign' is seen as a hyperechoic irregular rim over the articular cartilage, and is considered a speific feature of gout, and is believed to be secondary to MSU crystals on the cartilage.

Reference:
S. Dhanda, A re-look at an old disease: A multimodality review on gout, Clinical Radiology, Volume 66, Issue 10, October 2011, Pages 984-992

Sonography of scrotum

Regarding ultrasound of scrotum,
1. Increased blood flow to the epididymis is the most sensitive sign of epididymitis
2. Epidermoid cysts have characteristic alternating hyper and hypoechoic bands
3. Epididymal papillary cystadenomas are associated with Osler-Rendu-Weber syndrome
4. Adenomotoid tumors are the most common spermatic cord tumours.
5. Adenomatoid tumours of the epididymis most often arise from the head.

Answers: F, T, F, F, F

Notes: Increased size of epididymis and/or scrotum is the most sensitive sign of epididymoorchitis on ultrasound. Epididymal papillary cystadenomas are associated with von Hippel Lindau syndrome. Adenomatoid tumors are the most common benign solid tumours of epididymis (most often arise from tail), and lipomas are the commenest spermatid cord tumours.

Reference: Stengel JW et al. Sonography of the scrotum: case based review. AJR June 2008. S35-S45

Hypoxic ischaemic brain injury

In evaluation of hypoxic ischaemic brain injury,
1. Diffusion weighted images are more sensitive than MR spectroscopy in acute setting
2. Most of the germinal matrix haemorrhage occur within 24 hours of birth
3. Cerberal cortex is more often involved in hypoxic injuries than deep grey structures in neonates and pre-term babies
4. Normal appearance on diffusion weighted images by the end of first week of hypoxic insult indicates reversal of hypoxic insults
5. Germinal matrix haemorrhage extending into ventricles is graded as IV

Answers: F, T, F, F, F

Notes: Diffusion weighted images are more sensitive than T1 and T2 weighted images, but MR spectroscopy is more sensitive than diffusion weighted images. MRS shows increased lactate in the deep gray matter, parieto-occipital region, and watershed zones as early as 2-8 hours. Germinal matrix haemorrhage is more often seen in pre-term babies born weighing less than 2000g and majority of the bleeds occur within 24 hours of birth. Deep grey structures are more often involved than cerebral cortex in both neonates and pre-term babies. Thalami, anterior vermis and dorsal brainstem are more frequently involved in pre-term babies, where as in full term neonates basal ganglia are more often involved. Diffusion-weighted images, although sensitive in diagnosing hypoxic damage, but they often underestimate the extent of the injury. Diffusion-weighted images also tend to normalise by end of the 1st week, but do not imply reversal hypoxic insult (pseuonormalization). Germinal matrix haemorrhages are graded into: Gr1 – subependymal haemorrhage without or minimal intraventiruclar bleed; gr 2 – germinal matrix and intraventricular haemorrhage without ventricular dilatation; gr 3 – gr 2 + ventricular dilatation; gr 4 – periventricular parenchymal haemorrhagic infarct

Reference: Huang BY et al. Hypoxic-Ischemic Brain Injury: Imaging Findings from Birth to Adulthood. RadioGraphics 2008;28:417-439

Inguinal and Femoral Hernias

Regarding Femoral and Inguinal Hernias,

1. The indirect inguinal hernia is seen lateral to the inferior epigastric artery
2. The direct inguinal hernia has more potential for obstruction then indirect hernia
3. It is possible to classify the inguinal hernia based on ultrasound
4. Femoral hernias are seen in the posterolateral quadrant, when two perpendicular lines are drawn along the lateral edge of the pubic tubercle on the axial slices.
5. Coronal reformations are very useful in diagnosing incidental femoral hernias

Answers: T, F, F, T, T

Notes: The indirect inguinal hernia is seen lateral to the inferior epigastric artery and the direct is seen medial to it. The indirect inguinal hernia is congenital (failure of closure of internal inguinal ring) and the direct is secondary to weakness in the Hesselbach triangle. The indirect inguinal hernia is more prone for complication such as obstruction. Multislice CT is useful in identifying the inferior epigastric artery and helps in differentiating direct from indirect inguinal hernia. Two perpendicular lines are drawn along the lateral edge of the pubic tubercle. Femoral hernias lie in the posterolateral quadrant and the inguinal in the anterior half. Indirect are more medial and the direct or more lateral. Coronal reformations demonstrate "Radiological femoral triangle" which is normally fat filled and useful in demonstrating incidental hernias.

Reference: Cherian PT and Parnell AP. Diagnosis and Classification of inguinal and femoral hernia on multisection spiral CT. Clinical Radiology (2008) 63: 184-192

Gestational Trophoblastic disease

Regarding gestational trophoblastic disease (GTD),

1. Incomplete moles are more likely to undergo malignant change than the complete moles
2. GTD is almost always completely curable with preservation of fertility
3. Lymphnode involvement is a rare feature of choriocarcinoma
4. GTD usually shows low resistance blood flow
5. It is rare to have other metastasis in the absence of lung metastasis

Answers: F, T, T, T, T

Notes: GTD includes complete mole (46XX diploid), incomplete mole (triploid), invasive mole, choriocarcinoma and placental site trophoblastic tumour. 16% of complete and 0.5% of partial moles undergo malignant changes. Lymph node involvement in GTD raises a possibility of rare GTD, placental site trophoblastic tumor, as lymphnode involvement is rare in choriocarcinoma or invasive moles. Uterine volume has prognostic implications in GTD. The normal PI is more than 1.5 and in GTD, there is low resistance flow, leading to decrease in PI. PI indirectly measures tumor vascularity. With exception of vaginal metastasis, it is rare to have other metastsasis in the absence of lung metastasis. The lung metastasis are usually rounded, measuer up to 3 cm, rarely cavitate, can be miliary, may block pulmonary arteris and cause PE symptoms.

Reference: Allen SD et al. Radiology of gestational trophoblastic neoplasia. Clinical Radiology Volume 61, Issue 4, April 2006, Pages 301-313

Limbic encephalitis

Regarding limbic encephalitis (LE),

1. Usually presents with long term memory impairment
2. MRI typically shows high signal on T2 and FLAI in the limbic region
3. The most common underlying malignancy is small cell lung cancer (SCLC)
4. PET is useful in diagnosing underlying occult malignancy

Answers: F, T, T, T,

Notes: LE usually presents with short term memory impairment, seizures, confusion and psychiatric symptoms. Brain stem may also be involved. LE can be paraneoplastic or non-paraneoplastic. SCLC is the most common cause; other causes include testicular cancer, ca breast, teratoma, HL, thymoma. Although LE can be idiopathic, underlying malignancy should be searched.

Reference:
Rutherford GC et al. Imaging in the investigation of paraneoplastic syndromes. Clinical Radiology Volume 62, Issue 11, November 2007, Pages 1021-1035

Jejunum

Regarding jejunum,

1. Jejunal valvulae conniventes are more numerous than ileal ones
2. Jejunal valvulae conniventes are 1 mm thick
3. Jejunal valvulae conniventes are characteristically spiral shaped
4. Low density barium is widely used as oral contrast for the CT evaluation of the jejunum in the UK
5. Jejunum accounts for 40% of small bowel

Answers: T, F, F, F, T

Notes: Jejunal valvulae conniventes are more numerous than ileal ones, measure 2mm in thickness and are circular in appearance. Ileal ones measure 1 mm and are spiral in appearance. Water is commonly used as oral contrast in the UK.

Reference:
Hyland R et al. CT features of jejunal pathology.Clinical Radiology Volume 62, Issue 12, December 2007, Pages 1154-1162

Lymphoma

Regarding lymphomas,

1. Mesenteric nodes are commonly involved in Hodgkin's lymphoma
2. Nodal extension is contiguous in HL
3. Extranodal disease is common in NHL
4. Testicular lymphoma is the most common testicular tumor in people aged over 60 years
5. Adrenals are common extranodal sites for lymphomatous involvement

Answers: F, T, T, T, F

Notes: Axial, peripheral and mesentric nodes are commonly involved in NHL and mesentric nodes are rarely involved in HL. Nodal extension may be non-contingious in NHL, usually contigious (more often single nodal group) in HL. Extranodal disease is rare in HL (4-5%), common in NHL (20-40%). Lymphomatous involvement of kidneys is usually bilateral and contiguous retroperitoneal extension is seen with renal lymphoma in 25% and should not be mistaken for RCC. Involvement of adrenal in is rare (only 4% of NHL). In up to 40%, testicular lymphoma is bilateral and multifocal and is most common testicular tumor in people over 60 years. Gastric lymphomas account for 3-5% of gastric malignancies and far less common than adenocarcinomas and GISTs.

References:
Liete NP et al. Cross-sectional Imaging of Extranodal Involvement in Abdominopelvic Lymphoproliferative Malignancies.RadioGraphics 2007;27:1613-1634

CNS complications in paediatric oncology

Regarding CNS complications in paediatric oncology patients,

1. Intratumoral hemorrhage is most often seen with osteosarcoma metastases.
2. Children with Wilm's tumour are at high risk of reversible posterior encephalopathy.
3. L-Asparginase, which is used in treating ALL, is associated with sinus venous thrombosis.
4. Aspergillus is the most common lethal fungal infection.
5. The dissemination of tumore via CSG occurs more frequently in paediatric age than in adults.

Answers: T, T, T, T, T

Notes:
Sarcomas are most commonly associated with intratumoral bleed in brain and osteosarcoma is the most common sarcoma to matastasize to brain in paediatric age group. Reversible posterior encephalopathy is seen in children with elevated blood pressure (on steroids), Wilm's tumor and the children on Cyclosporin-A. L-Asperginase is associated with sinus venous thrombosis. Methotrexate is associated with reversible perventricular white matter signal abnormality. Aspergillus is the most common lethal fungal infection and usually appear as intermediate signal on T2 and PD sequences; they may not show enhancement, because of lack if inflammatory response.

Reference:
Chu WCW et al. Imaging findgins of paediatric oncology patients presenting with acute neurological symptoms. Clinical radiology (2003) 58:589-603

Tuberculosis

Regarding tuberculosis,

1. Radiographic evidence of hilar lymphadenopathy is more common in adults than in children
2. Cavitation is hallmark of post-primary TB
3. In TB meningitis, abnormal meningeal enhancement is more often seen in the basal cisterns
4. In spinal TB, calcification of abscess is characteristic
5. Calcification is seen more than 50% of renal TB

Answers: F, T, T, T, T

Notes: Radiographic evidence of lymphadenopathy is more common in children (96%) than in adults (46%) and more often seen in the right hilar and right paratracheal location. Cavitation is hallmark of post-primary TB, where as lymphadenopathy is rare (5%). Calcification of abscess is highly specific of TB spine. In renal TB, calcification is seen in more than 50% and the other findings include calcyceal deformity and papillary necrosis.

Reference: Burrill J et al. Tuberculosis: A Radiologic Review. RadioGraphics 2007;27:1255-1273